CN103782306A - Method for encoding and simultaneously decoding images with multiple color components - Google Patents

Abstract

A method for encoding a latent image having at least two color components into a visible image is provided. First and second images associated with the first and second color components, respectively, are generated. The first image has a first pattern of elements processed based on corresponding color components provided in the latent image, and the second image has a second pattern of elements processed based on corresponding color components provided in the latent image. The first and second images are assigned first and second angles, respectively. The first image and the second image are aligned by orienting the first pattern of elements according to a first and a second angle, respectively. The aligned first and second images are overlaid to obtain an encoded image that is decoded using a decoder that simultaneously displays the first and second color components of the latent image to render a color composite image.

Description

Method for encoding and simultaneously decoding images with multiple color components

technical field

The present invention relates generally to the field of anti-counterfeiting and more particularly to the field of electronic and printed document protection using coded images.

Background technique

Document tampering and product counterfeiting are serious problems that have been addressed in several ways. One method uses a latent or hidden image applied to or printed on the item to be protected. These latent or hidden images are generally not viewable without the aid of specialized equipment to make them visible.

One way of forming a latent image is to encode the image optically so that when applied to an object it can be viewed by using a corresponding decoding device. Such images can be used on virtually any form of printed documents including legal documents, identification cards and paper, labels, currency and stamps. Such images can also be applied to merchandise or merchandise packaging that are susceptible to counterfeiting.

The article to which the encoded image is applied can be authenticated by decoding the encoded image and comparing the decoded image to an expected authentication image. An authentication image may include information specific to the item being authenticated or information related to a group of similar items (eg, products produced by a particular manufacturer or factory). Production and use of coded images can be controlled so that coded images cannot be easily copied. Furthermore, the coded image may be configured such that tampering with information related to the document or label is readily visible.

In existing systems, when an encoded image is decoded, the hidden content is revealed as a monochrome image. Alternatively, the hidden content is revealed as an image of the exact same color as would be set at each location in the printed artwork when no decoding device was used. Although the hidden content appears lighter or darker than the visible content, the image respects the colors present in the visible content. Using prior art methods, the color appearance of the hidden content cannot be engineered and the hidden content cannot be encoded in such a way that there is no visual correlation between the colors in the visible content observable with the naked eye and the colors in the decoded hidden content. What is needed is a process and method for encoding and decoding hidden images using two or more color components.

Contents of the invention

The present disclosure provides a computer-implemented method and system for encoding a latent image into a visible image based on encoding parameters, the latent image having two or more color components simultaneously revealed when a decoder is placed over the encoded image. The decoder includes decoding parameters that match the encoding parameters. The method produces a first image associated with a first color component and a second image associated with a second color component, the first image having a first pattern of elements processed based on corresponding color components of the latent image and A second pattern of elements that correspond to color component processing. A first angle is assigned to the first image and a second angle is assigned to the second image. The first and second images are aligned by orienting the first pattern of elements according to the first and second angles, respectively. The aligned first image and the aligned second image are overlaid to obtain an encoded image.

The present disclosure also provides a computer-implemented method and system for decoding a composite image with a latent image embedded therein. The decoded latent image includes first and second color separations oriented at different angles within the composite image, the first and second color separations being simultaneously revealed by placing the decoder over the composite image. The method includes determining a first angle associated with a first color separation of the latent image and determining a second angle associated with a second color separation of the latent image. A first color component is assigned to the first color separation based on the determined first angle, and a second color component is assigned to the second color separation based on the determined second angle. A decoder is provided to simultaneously display the first color component and the second color component of the latent image to render a color composite image.

Another aspect of the present disclosure provides a multi-layer decoder for decoding a composite image with a latent image embedded therein. The latent image is encoded into the composite image based on a plurality of coding parameters, and the latent image includes first and second color separations oriented at different angles within the composite image. Simultaneously reveals primary and secondary color separations by placing a multi-layer decoder over the composite image. The multi-layer decoder includes a first layer having first elements oriented along a first angle associated with a first color separation of the latent image. A second layer is attached to the first layer; the second layer includes a second element oriented at a second angle associated with a second color separation of the underlying image. The first and second layers are positioned relative to each other such that the first and second layers simultaneously reveal the first and second color components of the latent image to present a color composite image.

Yet another aspect of the present disclosure provides a single-layer decoder for decoding a composite image with a latent image embedded therein. The latent image is encoded into the composite image based on a plurality of coding parameters, and the latent image includes first and second color separations oriented at different angles within the composite image. Simultaneously reveals primary and secondary color separations by placing a single layer decoder over the composite image. The single layer decoder includes a first element oriented along a first angle associated with a first color separation of the latent image. A second element is provided and oriented along a second angle associated with a second color separation of the underlying image. The first and second elements are positioned relative to each other such that the first and second elements simultaneously reveal the first and second color components of the underlying image to present a color composite image.

Yet another aspect of the present disclosure provides a computer-implemented method of encoding two latent images into a visible image based on encoding parameters, the latent images having different content associated with two or more color components, to produce The rainbow effect that appears when a filter is placed over an encoded image. The decoder includes decoding parameters that match the encoding parameters. The method includes generating a first image associated with a first color component, the first image having a first pattern of elements processed based on corresponding color components provided in the latent image. A second image associated with a second color component is generated, the second image having a second pattern of elements processed based on the corresponding color component provided in the latent image, the second latent image including different content than the first latent image. The first image and the second image are superimposed to obtain an encoded image that visually resembles the visible image when viewed with the naked eye.

Description of drawings

A more complete understanding of the invention can be obtained by reading the following detailed description in conjunction with the accompanying drawings, in which like reference numerals are used to indicate like elements, in which:

FIG. 1 shows an example of encoding a latent image with two color components into a visible image according to an embodiment of the present invention;

Figure 2 shows an overlay of halftone screens according to an embodiment of the invention;

Fig. 3 shows a phase shifting segment for a halftone image according to an embodiment of the present invention;

4A-4C are schematic representations of component images used to generate a composite image in accordance with an embodiment of the invention;

5A-5B are schematic representations of component image elements produced in a method of producing a composite image according to an embodiment of the present invention;

6 is a schematic representation of component image elements generated in a method of generating a composite image according to an embodiment of the present invention;

Figure 7 shows a composite image generated in a method according to an embodiment of the invention;

Figure 8 is a schematic representation of component images used to generate a composite image according to an embodiment of the invention;

9 is a flowchart of a method of generating a composite image incorporating a latent image according to an embodiment of the present invention;

10 is a diagram of component images used to generate a composite image according to an embodiment of the present invention;

11 is an illustration of a composite image formed from a visible image screened using the composite image of FIG. 10 according to a method according to an embodiment of the present invention;

Figure 12 shows component images formed from visible images and used to generate composite images using a method according to an embodiment of the invention;

Figure 13 shows visible and latent component images used to generate a composite image using a method according to an embodiment of the invention;

14 is a schematic diagram of elements of a series of component images used to generate a composite image using a method according to an embodiment of the invention;

Figure 15 shows a visible image and two latent component images used to generate a composite image using a method according to an embodiment of the invention;

Figure 16 shows a side view, a bottom view and a top view of a decoder with two layers according to an embodiment of the invention;

17A-17C show different configurations for two-layer decoders according to embodiments of the present invention;

Figure 18 shows an example single-layer decoder for simultaneous decoding of latent image color components according to an embodiment of the present invention;

Fig. 19 shows an example of a single-layer decoder for decoding frequency-sampled color components according to an embodiment of the present invention;

Figure 20 illustrates a digital decoder for decoding and simultaneously displaying an encoded latent image with two or more color separations, according to an embodiment of the present invention;

21 illustrates a system for encoding and decoding images such that composite images encoded with latent images of two or more color components are displayed simultaneously, according to an embodiment of the present invention; and

Figure 22 shows a pattern of lens elements that may be used to view images produced using the methods of the present invention.

Detailed ways

The present disclosure provides methods of encoding and decoding images with color information. An image (hereinafter "composite image") may include two or more latent images embedded within a visible image. Alternatively, the composite image may include a latent image with two or more color separations embedded in the visible image. Synthetic images are placed on items that are susceptible to alteration, tampering and counterfeiting.

In this disclosure, "latent image" refers to an image that is manipulated and hidden in a visible image. When a composite image is generated from a latent image and a visible image, the human eye cannot discern the latent image from the composite image without the aid of a latent image rendering device ("rendering device") or a decoding device. One or more latent images may be hidden within the visible image, making it difficult to discern the latent images without a rendering device. In an alternative example, the underlying image may be visible but not readable because the underlying image content is systematically scrambled or otherwise manipulated within the composite image. This disclosure provides techniques for encoding a latent image with two or more color components into a visible image. The present disclosure also provides techniques for encoding two or more latent images generated using different color components into a visible image. The present disclosure also provides techniques for simultaneously decoding two or more color components associated with a latent image. Additionally, the present disclosure provides digital techniques for decoding latent images with color separation information such as different orientation angles or other color separation information.

As described herein, the latent image can be encoded into the visible image using optical encryption and optical steganography. In this disclosure, the term "optical encryption" describes the process of "scrambling" (ie, rendering unreadable) the underlying image until a matching optical decoder is placed over the composite image to descramble the hidden content.

According to one example, the latent image may be encoded into the visible image at selected angles for each of the two or more color components. For half-tone latent images, half-tone latent images associated with two or more color components may be encoded into the visible image at one or more selected frequencies. The selected frequency may be the same for each of the two or more color components. Alternatively, the selected frequency may be different for each of the two or more color components. Within each color component, phase shifting techniques can be applied to the underlying image embedded in the visible image. For example, halftone segments or line gratings can be phase shifted to account for the density pattern of the underlying image at a particular location. The rendering device may include elements configured correspondingly to the encoding parameters. For example, halftone encoding parameters may include selected encoding angles and encoding frequencies. The rendering device may also provide the color depth of the underlying image by decoding the density pattern of the underlying image's color components. Thus, the underlying image becomes visible when the rendering device is placed over the composite image. Those of ordinary skill in the art will readily recognize that other techniques than phase shifting can be provided to encode the underlying image.

Figure 1 shows an example of encoding a latent image into a visible image using two color components. The visible image 110 includes a first color component 112 and a second color component 114 . Latent image 116 includes heart-shaped item 117 generated using the first color component. Latent image 118 includes star item 119 generated using the second color component. Generated composite image 120 includes latent image 116 and latent image 118 embedded in visible image 110 . A decoded image 122 is revealed upon decoding the generated composite image 120 . As described below, decoded image 122 shows heart-shaped item 117 from latent image 116 and star-shaped item 119 from latent image 118 , with heart-shaped item 117 and star-shaped item 119 simultaneously displayed in their corresponding color components.

In FIG. 1 , color latent image 116 and color latent image 118 are respectively encoded into corresponding color components of visible image 110 . Encoding for the first color component may be performed by shifting the first color component halftone image by half a halftone frequency at a section within the first color component of the latent image where content exists. For example, the first screen frequency may be 200 lines per inch, and the first screen may be oriented at 75 degrees from the horizontal axis. The encoding of the second color component may be performed by shifting the halftone image at sections within the second color component of the latent image where content exists. The second screen frequency may be 200 lines per inch, and the second screen may be oriented at 15 degrees from the horizontal axis. As described below, a color latent image can be decoded using a two-layer rendering device having a first layer that matches the halftone parameters of the first screen and a second layer that matches the halftone parameters of the second screen . For example, a first screen may correspond to cyan and a second screen may correspond to magenta.

FIG. 2 shows an overlay 200 of a halftone screen. Overlay 200 shows halftone screens 202, 204 processed equally at all points with color component content of the underlying image. Therefore, the decoded latent image should include consistent or identical color intensity levels at all locations. This reduces the depth of each color component to two levels. A variation of this method can be implemented to encode a color latent image with more tonal levels for each color component. The quality of decoding a colored latent image can be improved by preserving the color depth of the hidden latent image. In other words, rather than providing a limited number of phase shifts at a given point in the decoded latent image, eg, full or no phase shifts, color component information can be preserved at a finer granularity during the encoding process.

Figure 3 shows an example of phase shifting a segment 301 of a halftone image using three phase shifts during the encoding process to preserve the color components. One of ordinary skill in the art will recognize that any number of phase shifts may be used to represent color density values between 0-100%. Displaced regions are shown at sections where content exists within corresponding color components of the latent image, including a partial shifted region 310 of 25% color density and a full shifted region 315 of 100% color density. During shifting, the segment 301 is moved to a selected area 302 adjacent to the segment 301 . No-shift regions 305 are shown for potential image segments that do not include content.

Expanding on the idea of Figure 3, the amount of segment shift can be comparable to the density value of the underlying image at a given point. For example, if the density value is 100%, you can apply the maximum shift (usually half of the decoder period) of the encoded fragment; if the density value is 50%, you can shift the fragment by 50% of the maximum possible shift; if A Density value of 25% shifts the fragment by 25% of the maximum possible shift; and so on. One of ordinary skill in the art will recognize that the shift value may be in any increment, eg, 10%, 1%, 0.1%, 0.01%, etc.

An optical decoder will show regions with different amounts of displacement due to different densities, thus giving the decoded latent image a color depth. According to one example, the maximum color depth and maximum number of colors that can be encoded can be determined by the ratio of the printing resolution to the encoding resolution. For example, if an image is printed at 2400 dots per inch, and if the image is encoded at 200 lines per inch, the width of the encoded element is 2400/200 = 20 dots. The full density of the hidden image within the coded image is usually achieved when the coded element is shifted by half its width (ie by 10 points). Thus, by applying a shift of 1, 2, ..., 10 pixels, 10 different density levels can be color-coded for each hidden image. This results in a total of 10^4 different colors for a four-color press. This method can be used to encode high-quality color images into visible images. According to one example, the coded latent image may exhibit improved quality if the method is used for a monochromatic latent image. This is due to the fact that a decoded image can be represented in multiple brightness levels instead of a binary image. The above concepts also apply to the following scrambling examples.

In this disclosure, the term "optical steganography" describes a process in which a plaintext or cryptographically modified image is used to reform a visible image by applying different transformations. For example, the segment line raster associated with the color components may be shifted to match the pattern of rendering elements provided on the rendering device. The latent image remains invisible to the naked eye until decoded by placing a matching rendering device over the visible image. Various techniques can be used to encode and decode latent and visible images.

As described in detail below, the coded latent image may be decoded optically using a software decoder or a rendering device (eg, a physical lens). A rendering device may include elements arranged in linear and non-linear patterns. The latent image or latent image color components may be encoded and decoded using a segment frequency that matches that of the rendering device or software decoder. For example, distort a segment of a latent image in a selected area to hide the latent image when viewed with the naked eye. The encoded latent image may be generated in digital form as described in U.S. Patent Application 13/270,738, filed October 11, 2011, or U.S. Patent No. 5,708,717, issued January 13, 1998, both of which are incorporated by reference in their entirety here. The encoded latent image can be produced in analog form using a dedicated camera, as described in US Patent No. 3,937,565, the entire contents of which are hereby incorporated by reference.

To achieve image authentication, an encoded latent image is embedded within a visible image (eg, a photograph, tint-type image, document, etc.) to form a composite image. The composite image can be printed on, affixed to, or associated with items, including documents, identification cards, passports, labels, products, product packaging, currency, stamps, holograms, and the like. According to one example, the encoded composite image may be produced using visible inks, invisible inks, specialty inks, toners, dyes, paints, lacquers, transmissive print media, and the like. Alternatively, the encoded composite image may be embossed, debossed, molded, laser etched, engraved, etc. on the article and affixed to the article. The composite image is used to authenticate the item and facilitate anti-counterfeiting efforts.

This disclosure describes various techniques for encoding multiple latent images or latent images with two or more color components into corresponding visible images. Techniques described by the same assignee for encoding a latent image into a visible image include: (1) combining multiple components to create a composite image, as in U.S. Patent Application 13/270,738, filed October 11, 2011, in its entirety The contents are hereby incorporated by reference; (2) using encryption and steganography methods, such as US Patent No. 7,796,753 issued September 14, 2010, US Patent No. 7,466,876 issued December 16, 2008, February 2005 U.S. Patent No. 6,859,534 issued on the 22nd and U.S. Patent No. 5,708,717 issued on January 13, 1998, the entire contents of which are hereby incorporated by reference; U.S. Provisional Patent Application 61/447,886, filed on , from which this application claims priority, and which is hereby incorporated by reference in its entirety.

Apply a single-layer decoding lens to decode composite color images created by combining multiple component images

According to one example, for example an image to be coded or scrambled may be divided into image parts or component images which may have complementary hues with respect to each other. The tone component images can be balanced with respect to selected characteristics (eg, color shade or other characteristics). The component images are sampled based on selected parameters (eg, frequency), and the sampled portions may be configured to provide a composite image, eg, that appears to the naked eye as a monotone image. Monotone can be a selected shade. As described herein, samples may be arranged according to parameters defined in corresponding decoders or rendering devices that may be used to view encoded, scrambled or latent images.

In one example, image portions may be extracted from at least two different images. Each of the different images may contribute an image portion that is encoded or scrambled to obtain a composite image. Image portions from at least two different images can be encoded or scrambled together to form a single composite image that can be decoded to reveal one or more hidden images.

According to one example, one or more latent images may be "hidden" within a visible image by composing a composite image as described herein. Rendering techniques such as halftonescreen, stochastic methods, dithering methods, etc. may be used to transform the composite image into a visible image. In another example, one or more latent images may be hidden within the visible image by creating a composite image derived from component image samples obtained from the visible image. The composite image can be created by obtaining a complementary inverse image portion for each corresponding image portion. Image portions and complementary inverse image portions can be patterned in pairs according to parameters such as frequency, and multiple pairs can be positioned adjacent to each other to present a composite image.

According to one example, encoding may be performed by overlaying the latent image over the visible image to identify visible image content regions corresponding to latent image content regions. At these identified visible image content regions, the inverse image content and corresponding image content may be exchanged or swapped. An encoded composite image is obtained by applying the technique on the composite image for each image part and complementary inverse image part pair. This technique enables the encoding of images without the need to divide the underlying image into color separations. Accordingly, the present disclosure supports encoding images by modifying a single parameter (eg, hue parameter) of the composite image.

After digitally generating the composite image, the composite image can be rendered using, for example, a halftone screen. Since the underlying image is encoded using the desired frequency for the image portion and complementary inverse image portion pair, the halftone screen can be printed with a halftone frequency that is greater than the desired frequency for the image portion and complementary inverse image portion pair. For example, the halftone frequency may be at least twice the desired frequency of the pair of image portions and complementary inverse image portions. Furthermore, halftone screen angles can be chosen to avoid, for example, Moiré effects between printed screens and coded elements. Those of ordinary skill in the art will recognize that various larger multiples of the halftone frequency can be used without causing disturbance to the composite image.

One example for generating a composite image includes digitally encoding the color latent image using the image portion and the complementary inverse image portion to produce an encoded color image. Another example for generating a composite image includes digitally encoding darkened and lightened versions of the color latent image. Alternative techniques for mixing colors into the composite image include transforming the color image into a color space that separates the image into intensity and color components, eg Lab, Yuv or HSI color spaces. Other color spaces may be used.

After the composite image is digitally encoded, the composite image can be printed using standard printing techniques (eg, halftone screen printing, random screen printing, and dither printing), among other printing techniques. As described in this article, if printing with halftones, the halftone frequency can be set to a frequency greater than that of the rendering device or the frequency of the decoder. For example, the halftone frequency may be at least twice the frequency of the rendering device or the frequency of the decoder. Those of ordinary skill in the art will recognize that various larger multiples of the halftone frequency can be used without causing disturbance to the composite image.

As described herein, an encoded image is provided in the form of a composite image composed of a plurality of component images. The present disclosure provides methods for hiding information into composite images using a multi-component approach.

The use of component images takes advantage of the fact that the human eye cannot discern minute details in encoded images. Coded images are typically images that are printed or otherwise displayed. The human eye tends to incorporate fine details of printed or displayed images. Therefore, printers are designed to take advantage of this human tendency. A printer produces a plurality of tiny dots or other structures on a print medium (eg, substrate, paper, plastic, etc.). Individual printed dots can be as small as a few thousandths of an inch in size and cannot be visually perceived by the naked eye. The human eye averages the dot pattern to create shades. For example, dot size or dot density determines perceived shade. If the printed dot size is larger, or if the printed dots are denser, the eye will perceive a darker tint. If the printed dot size is small, or if the printed dots are scattered, the eye perceives a lighter shade.

According to one example, the latent image may be split into component images of complementary hues. In this disclosure, the term "hue complementary" describes balancing component images with respect to a particular color. Thus, if corresponding elements are viewed together (eg, elements from corresponding locations on a component image), the eye perceives a color with respect to which it balances the component tones. The term hue value or hue means an intensity value or a color value.

Figure 4A shows first and second component images defining a latent image. In the component image 1 , the solid background 410 has the first color shade surrounding the area 420 . A secondary shade is provided to define the underlying image shown by the capital letter "USA". The tone value is reversed in component image 2 compared to component image 1 . The second shade covers the background area 410' while the area 420' defining the capital letter "USA" includes the first shade. The first and second shades are balanced with respect to a single shade such that if the component images were composited, the naked eye would only perceive the single shade and would not be able to distinguish the capital letters "USA". Each component image may be referred to as a "phase" of the original image.

According to one example, each phase may be divided into smaller elements according to a pattern corresponding to a pattern of a decoder or a rendering device. For example, rendering device patterns may be defined by lens elements. The lens elements may be linear elements (straight or curved) or segments eg corresponding to the lens elements of a lenticular lens. Alternatively, the lens elements may be in the form of a two-dimensional matrix of elements formed corresponding to a multi-element lens such as a fly's eye lens. In the example shown in Figure 4B, the component image is divided into an array of square elements 430, 430'. For example, the size and location of the square elements 430, 430' may correspond to elements of a fly's eye lens. The component element pattern may include frequencies corresponding to the frequencies of the lens elements (or one of the element frequencies). The component element pattern may have the same frequency (or frequencies for multidimensional patterns) as the lens element frequency (or frequencies). Alternatively, the component element pattern may have a frequency that is a multiple of the lens element frequency.

As shown in Figure 4B, elements 430, 430' corresponding to component image 1 and component image 2 may be systematically divided into sub-elements 432, 432'. Samples may be taken from the sub-elements 432, 432' and may be combined to form a composite image 440 having an average tone that matches the hue of the tint about which component image 1 and component image 2 are balanced. As shown in Figure 4C, the elements and sub-elements are large enough to make the underlying image easy to see. However, it should be recognized that if the elements of the composite image are small enough, the human eye will merge the elements together such that only a single uniform shade is perceived.

Composite images may appear devoid of content when viewed to the naked eye as a single uniform color shade or tone. However, the latent image becomes visible when a decoder or rendering device is placed over the composite image such that features of the decoder include frequency, shape and geometry corresponding to the pattern of sub-elements 432, 432'. In practice, the latent image is decoded when the decoder or rendering device is properly oriented on the composite image 440 . The decoder feature is configured to extract separately the composite image portion contributed by each of component image 1 and component image 2 . This allows a human observer to see the underlying image by looking at the decoder. Decoder characteristics may include magnification properties, and the particular component image viewed by a viewer may vary depending on the viewing angle through the decoder. For example, from a first-person perspective, a viewer may see an image with a dark inset on a light background. From a second perspective, the viewer sees a reverse image with a light inset on a dark background.

The example component images shown in FIGS. 4A-4C include two tints. However, it should be appreciated that the number of shades is not limited. According to one example for producing a single extrinsic tonal value in a composite image, multiple tints provided in two component images may be balanced with respect to a single tonal value. Alternatively, component images may be balanced with respect to multiple tonal values, in which case the resulting composite image has multiple extrinsic tonal values.

According to one example shown in FIGS. 4A-4C , composite images may be designed to cooperate with individual lenses (eg, fly-eye lenses) arranged in an array (eg, a square or rectangular grid). It should be understood, however, that the lens features may be formed in virtually any pattern, including symmetrical patterns, asymmetrical patterns, regularly spaced patterns, or irregularly spaced patterns. Furthermore, the lens features can be adapted to any shape. The size of the composite image element can be determined by decoding the characteristic size of the lens. As described herein, the sampling frequency of the component images can be calculated as a multiple of the decoder characteristic frequency. For example, the component images may be sampled at the same frequency as the lens features, or doubled or tripled.

In the example shown in Figure 4C, alternating parts of the component images form a composite image with a matrix pattern of the form:

It should be understood that other systematic approaches may be used to collect and order portions of component images to form a composite image and/or elements within a composite image. 5A and 5B illustrate, for example, a method of collecting and ordering portions of component images 500, 500' to form elements of a composite image 500". Components may be constructed using tonal values balanced about one or more selected tonal values. Image 500, 500'. The balanced values can be used to define a latent image.

In the example shown in Figures 5A and 5B, the component images 500, 500' are divided into elements 530, 530' each having a 2x2 pattern of sub-elements 532, 532'. This pattern is similar to that used in the example of Figure 4C. It should be understood that although a single example element 530, 530' is shown for each component 500, 500', the present disclosure supports dividing the entire composite image into a grid of such component images. As shown in FIG. 5A , diagonally opposite sub-elements A1 and A2 are obtained from each element (or unit) 530 of the first component image 500 . Similarly, diagonally opposite sub-elements B1 and B2 are obtained from the corresponding element 530' of the second component image 500'. Parts B1 and B2 can be chosen such that their exact positions are different from parts A1 and A2, as shown in Figure 5A. Alternatively, part B can be obtained from the same location as part A, as shown in Figure 5B. In either case, the selected portions are then used to construct composite image 500". In the example of FIG. at the exact location of elements A1, A2, B1, and B2. In the example of FIG. 5B, the B sub-element may be located at a slightly different location in the composite image than where the B sub-element was taken, so as to fill element 530". However, in both examples, from the same cell location The four sub-elements A1, A2, B1 and B2 are taken to ensure that the corresponding cell 530" in the composite image 500" has the same apparent hue value in either case.

Those skilled in the art will understand that the sub-elements 532, 532' may be other shapes than square. For example, sub-elements 532, 532' may include, but are not limited to, any polygon, circle, semicircle, ellipse, and combinations or portions thereof. For example, the component elements 530, 530' can be divided into two or four triangles. The component elements 530, 530' may also be formed as two rectangles forming a square element. For an image to be viewed using a fly's eye lens, component elements (or parts thereof) can be resized and shaped to correspond to the shape of the decoder features. Any combination of sub-element shapes may be used such that when combined sub-element shapes form corresponding element shapes. This disclosure contemplates mixing different shapes as long as the desired tonal balance is maintained. It is also possible to use child elements of different sizes within the composite image. Even if the total area belonging to each image component is not equal, any difference can be compensated for with a darker or lighter tone for one of the image components. For example, a first image area of 50% with a density of 60% associated with the first component and a second image area of 50% with a density of 40% associated with the second component would give 50% total color. However, using a first image area of 75% with a density of 60% associated with the first component and using a second image area of 25% with a density of 20% associated with the second component is also perceived as 50% % of the total color density. Another approach involves using different numbers of sub-elements from different components. For example, two sub-elements can be taken from the first component and four sub-elements can be taken from the second component as long as the tonal balance is maintained. According to these examples, since two component images are provided, half of each component image is used to form the composite image.

Fig. 6 shows an embodiment of producing a scrambling effect in a composite image. In this method, overlapping sampled portions are obtained from component images and downsized to form non-overlapping slices or sub-elements of a composite image. The difference in size between a component image portion and a sub-element of a composite image may be referred to as a scaling factor or a sub-element reduction factor. For example, for a scaling factor of 3, the component image parts should be three times the size of the sub-elements of the composite image. In this example, the component image portions are reduced in size by one third before being inserted into the composite image.

Fig. 6 shows first and second component images 600, 600' used to construct a composite image 600". According to one example, overlapping elements 650, 650' are obtained from corresponding component images 600, 600', overlapping Elements 650, 650' are reduced in size according to a scaling factor and placed as child elements 632" within element 630" to form composite image 600". It should be appreciated that although only two such sub-elements (ie, A1, A2, B1 and B2) are shown for each component image, the overlapping elements 650, 650' cover the entirety of the two component images 600, 600' . Each sub-element is positioned based on the configuration and frequency of decoder features and the configuration of sub-element 632". In the embodiment shown in FIG. 7, the overlapping elements are centered on the location of sub-element 632".

In FIG. 6 , the shaded area identified as element A1 in the first component image is reduced by a third in each dimension to create sub-element A1 of the composite image (ie, a scaling factor of 3 is applied). The child element A1 is centered at a position corresponding to the center of the element A1 in the component image. The large square identified as element A2 is reduced to one-third in each dimension to obtain sub-element A2 of the composite image 600", similarly, sub-element A2 is centered at a position corresponding to the center of element A2. Executing something like operation to obtain sub-elements B1 and B2 of the composite image 600".

The effect of using scaling factors to create a composite image is shown in FIG. 7 , which shows a composite image 700 formed from the component images in FIG. 4 . The pattern of elements and sub-elements in composite image 700 is configured to correspond to the characteristics of a matching decoder. The composite image of FIG. 7 was formed using a scaling factor of 4, although it is understood that any scaling factor could be used to form the composite image. Placing a matching decoder on the composite image will result in a "reassembly" of the component images 410, 410' for viewing by the observer, although the image parts making up the composite image appear in a scrambled manner. The viewer will then see the latent image 420, 420' within the corresponding component image 410, 410'. According to one example, the underlying image may appear to move or "float" as the observer changes his perspective through the decoder. This floating effect is produced by using already scaled overlapping component parts. The scaling effect spreads elements of the component image into multiple parts of the composite image. By adjusting the viewing angle, the decoder renders information from multiple parts of the component images, creating the illusion of floating. In general, the larger the zoom factor, the more pronounced the floating effect. On the other hand, by downscaling portions of the component images by a scaling factor, the effective resolution of the component images may be reduced when viewed through a decoding lens.

In some embodiments of the invention, elements of the component images may be flipped before being used to form the composite image. Flipping parts of a component image changes the direction in which those parts appear to float when viewed through a decoder. By alternating between flipping and non-flipping of elements of the component images, different parts of the component images may appear to float in opposite directions when viewed through a decoder.

In some cases, the above effects can be applied to a single component picture (or two identical component pictures) used to generate a non-tone-balanced encoded picture. Such an image may be used, for example, in applications where the decoder lens is permanently attached to the composite image. In such applications, tone balancing is not necessary since the underlying image is always viewable by the permanently attached decoder.

According to one example, a composite image may be formed from more than one latent (or other) image. For each such composite image, multiple component images can be created using the methods discussed previously. Portions from each component image can then be used to form a single composite image. For example, if it is desired to use two latent images (image 1 and image 2), each latent image can be used to form two component images. The two component images may each be divided into elements and sub-elements as shown in Figures 4-6. This results in four component images, each with corresponding elements and subelements. A composite image similar to FIGS. 5A and 5B may be formed using sub-element Al obtained from the first component of Image 1 and sub-element A2 obtained from the second component of Image 1 . Similarly, sub-element B1 may be obtained from the first component of Image2, and sub-element B2 may be obtained from the second component of Image2. In another example, sub-elements A1 and B2 may be obtained from components of image 1 , and sub-elements B1 and A2 may be obtained from components of image 2 . Child elements can be sorted in a number of ways. For example, child elements can be ordered on top of each other, side by side, diagonally across, or in any other way. Synthesizing images can produce the effect that a human observer can see different underlying images depending on the point of view through the decoder. Component images can alternate and switch as the viewing angle changes. Additionally, scaling factors and flipping techniques can be used with this technique. This can create a variety of effects available to the designer of the composite image. Any number of latent images can be hidden together in this way, and any number of component images can be used for each latent image.

According to another example, different scaling factors may be used for sub-elements obtained from different images. For example, a scaling factor of 2 may be used for subelements obtained from image 1 and a scaling factor of 8 may be used for phases obtained from image 2. Sub-elements obtained from different images can appear to be at different depths when viewed through a decoder. In this way, various 3D effects can be realized.

Figure 8 illustrates a method of collecting and ordering portions of component images to form elements of a composite image decodable using a lenticular lens. In Fig. 8, the two component images 800, 800' are divided into elements 830, 830' of shape and frequency corresponding to the characteristics of a decoder with a "wave-like" lens. As before, component images are created to balance about a particular shade (or shades). Composite image 800" is also formed by assembling sub-elements 832, 832' from component images 800, 800'. Scaling factors may be used if desired. In this example, the scaling factor is 1, indicating that the composite image elements have the same (i.e. there is no reduction in the component picture elements). The collection and ordering methods discussed herein can also be applied to wave-like decoders or any other type of decoder. In this example, the The first component image part (which is the light gray part) is acquired at the same geometric position as the dark gray part). The parts of the component images may be of equal size. The combined component image parts or elements of the composite image may cover parts of a single decoded feature in the composite image area.

If the component image portions used to create the composite image are small enough, and if the phases are balanced along the same shade, the techniques described herein can produce images that appear to be colored (ie, uniformly shaded) when printed.

FIG. 9 illustrates a general method 900 of generating a composite image according to an embodiment of the invention. The method 900 begins at S902, and at S904 a latent image is provided. Using the latent image, two or more component images are generated at S906. As described above, these component images are formed such that at each location, the tonal value is balanced with respect to a selected tonal value or color density. At S908, the image components are used to generate a plurality of image elements to be used to form a composite image. These composite image elements are formed and positioned according to the pattern and frequency of decoder features. As described above, component elements may be positioned and sized based on a frequency that matches or is a multiple of the decoder's frequency. In some embodiments, the component image elements are constructed by dividing the composite image into non-overlapping elements or units. In other embodiments, component image elements may be formed as overlapping elements or units.

At S910, content is extracted from each element of each component image. In embodiments where the component images are divided into non-overlapping elements, the act of extracting content may include subdividing each element of each component image into a predetermined number of sub-elements. Then extract the image content from the child element. The child element from which the content is extracted may be the reciprocal or multiple of the number of component images. Therefore, if two component images are used, half the sub-pixels are extracted from each element.

In embodiments where component images are used to generate overlapping elements, the content of each element may be extracted. As described above, a scaling factor may be applied to the extracted elements to produce sub-elements that may be used to form a composite image.

At S912, the content extracted from the component images is used to form a composite image. This can be done by placing a sub-element from each component in a location corresponding to the location in the component image from which the content of that sub-element was extracted. The method ends at S914.

Any or all of the steps provided in method 900, as well as any variations, can be implemented using any suitable data processor or combination of data processors and can be in the form of software stored on any data processor or on a non-transitory computer readable medium to fulfill. Once digitally produced, the encoded composite image may be applied to the substrate by any suitable printing, embossing, intaglio, molding, laser etching, or surface removal or deposition techniques. Images may be printed using the following media: inks, toners, dyes, pigments, transmissive print media as described in U.S. Patent No. 6,980,654, issued December 27, 2005, which is hereby incorporated by reference in its entirety; non-visible Spectral (eg, ultraviolet or infrared) print media, as described in US Patent No. 6,985,607, issued January 10, 2006, which is hereby incorporated by reference in its entirety.

It should be understood that there are many ways to compose balanced image components. In various embodiments, balanced component image portions may be created by inverting portions of one component image to form portions of a second component. If this method is used, the component images can be balanced about 50% density, and the composite image appears 50% color to the naked eye. When printed or otherwise displayed, the elements of the composite image can be printed adjacent to each other and the eye will average them as (60%+40%)/2=50%. Another example for generating a composite image includes digitally encoding darkened and lightened versions of the color latent image. One component can be darkened by using an intensity/color curve designed for darkening, and the other component can be brightened in each position by the same amount as the first component was darkened. Alternative techniques for mixing colors into a composite image include transforming the color image into a color space that separates the image into intensity and color components, for example, Lab, Yuv, or HSi color spaces, and converting the intensity/color curves described above to applied to these color spaces. Other color spaces may be used.

In some embodiments of the invention, a color-based composite image may be integrated or embedded into a visible image, eg, any visible artwork. The composite image can be hidden from the naked eye in the visible image, but is not hidden but presented when the decoder is placed over the printed visible image or the composite image. All effects associated with composite images (ie, appearance of floating, alternation of component image viewability, etc.) can be preserved.

One approach to this is to apply the halftone screening technique described above, which uses the composite image as a screen file to halftone the visible image. The technique can modify the elements of a composite image by resizing the elements to mimic the density of visible image fragments at the same location. In this method, the composite image has no more than two intensity levels in each of its separations. The corresponding color separations of the composite image are used as screens for the visible image. If the color components of the composite image are not two-level, the color components can be preprocessed to meet this need.

Figures 10 and 11 show examples of this method. Figure 10 shows two component images 1000, 1000' constructed based on the capital letter "USA" latent image, which are used to construct a composite image 1000" formed from square elements of the two component images 1000, 1000'. As described herein As described above, the basic composite image appears to the naked eye as a monotone image. However, the zoom-in shows that the composite image 1000" is formed from multiple sub-elements. Each of these sub-elements is a square portion taken from a corresponding element of one of the component images 1000, 1000'. It should be understood that all of these sub-elements have the same size and shape. Rectangles of varying size appear in the zoomed-in area due to content changes within child elements. Placing the corresponding decoder on the composite image 1000""reassembles"the content so that the component images 1000, 1000' with the latent image can be viewed.

Figure 11 shows a visible image 1110 and a halftone 1110' of that image screened using the composite image 1000" of Figure 10. The unmagnified halftone image 1110' appears unchanged to the naked eye. Image 1110 ′ is shown composed of square elements of a composite image that has been modified according to the tonal density of original image 1110 . In fact, composite image 1000 ″ of FIG. 10 is embedded within visible image 1110 . The component images 1000, 1000' will be visible when the decoder is placed over the encoded image (i.e. the halftone composition 1110').

FIG. 12 illustrates another method of hiding latent images within visible images 1200 . As previously described, the component images 1210, 1210' may be formed by tone balancing corresponding locations in different regions with respect to different tonal densities. The method may be used to create component images 1210, 1210' from the visible image 1200, as shown in FIG. 12 . One approach is to darken the visible image 1200 to create a first duplicate image, and correspondingly brighten the visible image 1200 to create a second duplicate image. Regions matching the latent image can be masked from each replicated image and replaced in each case by the content of the masked region from the other replicated image. In the example shown in FIG. 12, the region of the visible image 1200 that is aligned with the letters "USA" (ie, the latent image) is essentially swapped between the replicated images to produce component images 1210, 1210'. The component images can then be sampled and combined to create a composite image 1210" using any of the techniques discussed herein. The composite encoded image 1210" is nearly similar to the original image 1200, but with the hidden message "USA" in it viewable using a decoder , the decoder corresponds to the size and configuration of the elements used to form the sub-elements of the composite image 1210″.

Another method of hiding a latent image within a visible image is to use both the visible image and the latent image to create corresponding component images. This method is illustrated in FIGS. 13 and 14 . Figure 13 shows (in gray scale) a color visible image 1300 of a tiger, and a color latent image 1310 of a girl. In this example, visible image 1300 is used to form four identical component images 1300A, 1300B, 1300C, 1300D, which are divided into elements 1430A, 1430, 1430C, 1430D , as shown in Figure 14. For example, matched decoders may include rectangular or elliptical lenses. As in the previous examples, only a single element is shown for each component image, but it should be understood that the elements are formed over the entire component image. It should also be understood that for illustrative purposes, elements are shown in Figure 14 that are much larger than the actual elements used in the method of the present invention. In the illustrated embodiment, each element of the four components is divided into sub-elements 1432A, 1432B, 1432C, 1432D. In this example, since a total of six components are used to generate the composite image, the component image elements are divided into six sub-elements.

It should be understood that it is not actually necessary to create separate component images of the visible image. The visible image itself can be used to generate the elements and sub-elements used to make up the composite image.

The latent image 1310 is used to generate two corresponding component images 1310A, 1310B. The second component image 1310B is generated as an inverse image of the first component image 1310A. The first and second component images 1310A, 1310B are divided into elements 630E, 630F, which may be non-overlapping elements (as shown in FIG. 11 ) or overlapping elements like that shown in FIG. 3 . As with component images corresponding to visible images, each element of latent component 1310A, 1310B is divided into sub-elements 1432E, 1432B, 1432C, 1432D. Likewise, six child elements are formed from each element.

In this example, it is intended that the visible image is visible to the naked eye and the latent image is visible by means of a decoder configured to correspond to encoding parameters consisting of components from the visible and latent images 1300A, 1300B, 1300C, 1300D, 1310A and 1310B Frequency of extracted elements. Therefore, most of the sub-elements used are obtained from the visible component images 1300A, 1300B, 1300C, and 1300D corresponding to the visible images when composing the composite image. In the example shown, four of the six sub-elements used in each element 1422 of the composite image 1420 (A1, B2 , C4 and D5). The other two sub-elements (E3 and F6) used in element 1422 are extracted from the latent component images 1310A, 1310B corresponding to the latent images. Sub-elements E3 and F6 are interleaved with four sub-elements Al, B2, C4 and D5 extracted from the visible image. Sub-elements E3 and F6 are invisible to the naked eye because compensating the sub-elements E3 and F6 extracted from the latent image swaps the original image color for one sub-element with the inverse image color for the other sub-element. In other words, the eye blends the corresponding sub-elements E3 and F6 into a 50% color. As in the previous embodiments, the child elements used within the element 1422 of the composite image 1420 and their positions may vary.

Since the sub-elements originating from visible image 1300 have not changed in any way, the viewer will still see the tiger image in composite image 1420 with the naked eye. However, under a properly oriented decoder, the composite image elements will be visually grouped such that for some viewing angles the viewer will see the visible image 1300 (e.g., the tiger of Figure 13) and for other viewing angles the viewer will see The latent image 1310 (eg, the girl of FIG. 13 ), and for still other viewing angles, the viewer will see the inverse of the latent image 1310 . In this way, the color latent image 1310 and its inverse are hidden within the color visible image 1300 . Additional effects may be added to the decoded image by applying element flipping and/or a scaling factor greater than 1 to the latent component images 1310A and 1310B generated from the latent image 1310 .

In a variation of the above embodiment, instead of using most of the sub-elements from visible image 1300 for each composite image sub-element A1, B2, C4, D5, E3, and F6, visible image 1300 may be preprocessed to Increase its contrast. This allows reducing the number of sub-elements extracted from the visible image 1300 in order to hide the latent image 1310 .

In any of the embodiments described herein, the visible and latent images used to create the composite image may be binary images, grayscale images, color images, or a combination of any type of image. Thus, the component images revealed by the decoder can be binary, grayscale or color images.

Multilayer Decoder for Simultaneous Decoding of Latent Image Color Components

As described herein, a composite image may include a latent image encoded into a visible image using two or more color components. Although a composite image may include multiple color components, the color components may be mixed to produce a monotone image. For example, mix equal amounts of cyan, magenta, and yellow. The techniques described herein enable the encoding and decoding of a color latent image in what appears to be a uniform visible image. A visible image includes content variations such that the observer cannot correlate the colors revealed by the decoding device with the colors seen by the naked eye. According to one example, the latent image is divided into at least two color component separations corresponding to the color components available in the visible image. The color-separated latent image is encoded into the corresponding color components of the visible image based on the encoding parameters determined by the features of the matching decoder. For example, encoding parameters may include relative angles for depositing particular color components and frequency of decoding elements (eg, lenses) for decoding a composite image, among other parameters.

Figures 16 and 17 show an example of a multi-layer decoder or rendering device with two layers. The elements (or lenses) in each layer of the multi-layer decoder are arranged according to selected frequencies or patterns corresponding to the underlying image color components. The elements (or lenses) in each layer of the multi-layer decoder are also oriented to match the relative angles at which the underlying image color components are deposited on the substrate. Each layer of a latent image can be decoded simultaneously when the encoding parameters of the latent image match the characteristics of the corresponding presentation layer. One of ordinary skill in the art will recognize that more than two rendering devices may be used to simultaneously decode potential images associated with more than two color components.

Figure 16 shows the components of a two-layer decoder. The first rendering device 1601 is shown in a side view 1602 and a bottom view 1604 . Second presentation device 1610 is shown in side view 1612 and top view 1614 . As shown by the adjacent placement of the first rendering device 1601 and the second rendering device 1610 in FIG. 16 , the first layer element 1605 is oriented substantially perpendicular to the second layer element 1615 . The two color component layers associated with the two latent images are then oriented to match the angles of the corresponding first layer elements 1605 and second layer elements 1615 . Thus, each layer of the latent image is decoded simultaneously to provide a multi-color decoded image.

Although the first rendering device 1601 and the second rendering device 1610 are illustrated as including a linear lens, one of ordinary skill in the art will readily recognize that the first rendering device 1601 and/or the second rendering device 1610 may include a non-linear lens. Non-linear lens structures may include wavy line structures, zigzag structures, fishbone structures, arc structures, unconstrained structures, and the like. According to an example, the first rendering device 1601 and the second rendering device 1610 may include the same lens structure or different lens structures. Furthermore, a multilayer lens may include layers formed using different techniques, for example, having a first layer formed using a molded lens array and a second layer formed using a screen printing process.

As shown in Figures 17A-17C, the first presentation device 1601 and the second presentation device 1610 may be positioned relative to each other in a variety of configurations. Arrow 1700 shows the viewing direction. As shown in Figure 17A, the first rendering device 1601 and the second rendering device 1610 may be positioned such that the first layer element 1605 and the second layer element 1615 face inwardly towards each other. When the first layer element 1605 is oriented towards the image, the first layer element 1605 decodes the image by the second rendering device 1610 . In this case, the second rendering device 1610 is positioned in physical contact with the encoded image.

In a second example shown in Figure 17B, the first rendering device 1601 and the second rendering device 1610 may be positioned such that the first layer element 1605 and the second layer element 1615 face outwardly away from each other. In this configuration, the first rendering device 1601 may be positioned slightly above the encoded image so that the first layer element 1605 can focus on the encoded image.

In a third example shown in FIG. 17C, the first rendering device 1601 and the second rendering device 1610 may be oriented in the same direction such that both the first layer element 1605 and the second layer element 1615 face upward. In this case, the curvature of the first layer element 1605 and the second layer element 1615 can be designed such that the first layer element 1605 and the second layer element 1615 focus on the bottom surface of the multilayer decoder.

In the above example, the frequencies of the first layer elements 1605 and the second layer elements 1615 may be the same or different. For example, the frequency of the first layer elements 1605 and the second layer elements 1615 may be 250 lines per inch. Alternatively, the frequency of the first layer elements 1605 and the second layer elements 1615 may be: 200 lines per inch for layer 1 and 250 lines per inch for layer 2 .

Single-Layer Decoder for Simultaneous Decoding of Latent Image Color Components

As described herein, a composite image may include a latent image encoded into a visible image using two or more color components. Although a composite image may include multiple color components, the color components may be mixed to produce a monotone image. For example, mixing equal amounts of cyan, magenta, and yellow creates an image that appears to have an even brown tone. The techniques described herein enable the encoding and decoding of color latent images in visible images that appear to be uniform or that vary in content, where the observer cannot correlate the colors shown with the decoding device with the colors seen by the naked eye.

According to one example, the latent image is divided into at least two color component separations corresponding to the color components available in the visible image. The color-separated latent image is encoded into the corresponding color components of the visible image based on the encoding parameters determined by the features of the matching decoder. For example, encoding parameters may include the relative angles used to deposit a particular color component and the frequency of decoding elements (eg, lenses) used to decode the composite image, among other parameters.

Figure 18 shows an example microarray lens matrix 1800 configured on a single layer. Elements or lenticular elements 1802 are arranged according to selected frequencies or patterns corresponding to latent image color components. For example, path 1 (1810) and path 2 (1815) are illustrated as having the same frequency, while path 3 (1820) is illustrated as having a higher frequency. According to one example, the frequency is controlled by adjusting the distance between the rows of microarray elements 1802 corresponding to the paths. Increasing the distance between rows of microarray elements 1802 may correspond to decreasing frequency, and decreasing the distance between rows of microarray elements 1802 may correspond to increasing frequency. According to one example, microlens elements 1802 may include the same lens structure or different lens structures.

The microlens elements 1802 are also oriented along one or more of Path 1 (1810), Path 2 (1815), and Path 3 (1820) to match the relative angles at which the underlying image color components are deposited on the substrate. Although paths 1-3 are illustrated as linear paths, the present disclosure supports non-linear paths. Non-linear paths may include wavy line paths, zigzag paths, fishbone paths, arc paths, unconstrained paths, and the like. When the encoding parameters of the latent image match the characteristics of the single layer microarray lens matrix 1800, each layer of the latent image can be decoded simultaneously. Those of ordinary skill in the art will readily recognize that more than three paths may be provided to simultaneously decode potential images associated with more than three color components. One of ordinary skill in the art will also recognize that microlens elements 1802 may be arranged in other matrix configurations that support multiple decode paths with equidistant lens elements matching the frequency and angular orientation used for the encoding process. Such matrix configurations include hexagonal grid configurations, concentric ring configurations, or other configurations.

According to another example, the encoding process may arrange the microlens elements 1802 to support variable frequencies. In this case, the distance between microlens elements 1802 varies along the path. According to one example, if the microlens element 1802 is positioned along a path corresponding to the linear path used for the encoding process, the microlens element 1802 samples the encoded image and recreates the latent image. By sampling parts of a fragment instead of decoding the entire fragment of the encoded image, the decoded image can appear slightly jagged. However, if the frequency of the encoding process and the frequency of the microlens elements 1802 is high enough, eg, greater than 140 lines per inch, the above effect is not significant.

Single-layer decoder for simultaneous decoding of frequency-sampled color components

According to one example, the latent image is divided into at least two color component separations corresponding to the color components available in the visible image. In this example, four color component separations are used, and a linear lenticular decoding lens is provided to decode the four color component composite image.

As shown in Figure 19, the lenticular lines used in the encoding process can be divided into four subsets matching the four separations provided in the visible and latent images. The four subsets include black segment 1901 , yellow segment 1902 , magenta segment 1903 and cyan segment 1904 . In other words, one quarter of the fragments could be used to encode the black separation, another quarter of the fragments could be used to encode the yellow separation, another quarter of the fragments could be used to encode the magenta separation, and the last quarter The fragments can be used to encode cyan isolates.

According to an example, the subsets 1901, 1902, 1903, 1904 may be interleaved. For example, lines 1, 5, 9, 13, 17, etc. include a first subset of black segments 1901 corresponding to black components. Lines 2, 6, 10, 14, 18, etc. include a second subset of yellow segments 1902 corresponding to yellow components. Lines 3, 7, 11, 15, 19, etc. include a third subset of magenta segments 1903 corresponding to magenta components. Lines 4, 8, 12, 16, 20, etc. include a fourth subset of cyan segments 1904 corresponding to cyan components. The color components of the latent image are encoded into appropriate subsets 1901 , 1902 , 1903 , 1904 . In this example, the frequency used for the encoding method is one quarter of the decoder frequency. In this example, the same encoding angle is applied to each subset 1901 , 1902 , 1903 , 1904 .

In FIG. 19, an image with cyan, magenta, yellow, and black color separations printed at 25 degrees in a line screen is shown. Each color component of the visible image is encoded with the corresponding color component of the latent image. When the decoder is placed on the composite image, the decoder simultaneously decodes all color components including black, yellow, magenta and cyan components. The decoded composite image reveals the composite color latent image.

This disclosure contemplates several variations on the methods described above. For example, instead of using the same frequency for all color components, more line repetitions can be used for one of the separations. This results in a higher frequency for the selected separation. This disclosure also contemplates using different screen elements for different color separations. For example, straight segments can be used for some color separations, and wavy segments can be used for other color separations. Another variation includes arranging lenticular lenses or microarray lens elements to follow a non-linear pattern (eg, a pattern of concentric rings). Non-linear patterns can be generated by dividing the decoder elements into subsets. The number of subsets can match the number of color components of the latent image, and the color separations of the latent image can be encoded into these subsets.

According to one example, frequency-sampled color components should be applied to brighter images, including images with color separations in the 0-25% density range. This disclosure contemplates encoding and decoding color latent images using arbitrary lenticular patterns, where the different color components of the latent image are encoded into elements in the visible image that match a specified subset of the decoder pattern. Each separation of the encoded image is printed using the same separation from the underlying image. For example, encoding the cyan separation of the latent image into the cyan separation of the visible image.

Use multiple underlying images to create rainbow effects or color changes

The above examples describe techniques for creating a polychromatic latent image encoded into a visible image. For example, a polychromatic latent image may include different color components provided within the composite image. The degree to which the decoded color latent image matches the color latent image used for encoding is largely dependent on the quality and resolution of the equipment used to apply the encoded image to the article.

For applications where high-quality and high-resolution printers are not available, such as printing passport images encoded with personal data, it may be difficult to achieve consistent color matching between the color image used for encoding and the color image decoded after applying the image to the item . This can also be due in part to variations in the visible image (eg, different for each passport photo). In these cases, authentication can be accomplished, for example, by adding a second latent image that provides color variation or vivid color attributes to the encoded composite image without requiring a good color match between the intended and decoded color images. This encoding process can be performed at a processing speed comparable to the lower limit processing speed required to generate personal information for embedding in a visible image.

To speed up the process for encoding color separations into visible images, repeated monochrome latent images can be provided. As described herein, inversion processing can be used to process the latent image or portions of the latent image. When the decoder is placed over the printed encoded visible image, color differences are discernible between the latent image and the surrounding visible image. Alternatively, a process for changing the brightness of the latent image or part of the latent image may be provided prior to encoding the latent image into a particular color separation of the visible image. When the decoder is placed over the printed encoded visible image, changing the brightness of the latent image results in a discernible color difference between the latent image and the surrounding visible image.

The process of inverting a latent image or changing the brightness of the latent image to encode the latent image into a visible image (eg, a photograph) does not provide constant results when applied to personal documents (eg, passports and driver's licenses). One reason is that photographic images of subjects are unique, and thus encoded photographic images may include unique color variations when decoded using an optical decoder. One technique that may be applied to standardize the process of authenticating personal documents includes providing a second latent image as described below.

15 shows a visible image 1510 representing a photograph of a subject, a first latent image 1515 having a first pattern generated using a red component, a first latent image 1520 having a first pattern generated using a blue component, and a first latent image 1520 having a first pattern generated using a green color component. The second latent image 1525 of the second pattern generated by the component. As shown, the content of the first latent image 1515 , 1520 is different from the content of the second latent image 1525 . One of ordinary skill in the art will recognize that other content differences may be provided between the first and second latent images.

According to one example, the first latent image 1515 shows the capital letter "JANE" rendered against a black background, the capital letter "JANE" being generated using a red component. The first latent image 1520 shows the capital letter "JANE" rendered against a black background, the capital letter "JANE" being generated using a blue component. Those of ordinary skill in the art will readily recognize that different content may be provided for the first latent image.

A second latent image 1525 shows the capital letter "JANE" rendered against a white background 1527, with the capital letter "JANE" 1526 being generated using a green component. The second latent image 1525 also shows the capital letter "JANE" rendered against a black background 1528, the capital letter "JANE" being produced based on the absence of ink. Those of ordinary skill in the art will readily recognize that different high-contrast content may be provided for the second latent image.

Synthetic image 1530 is generated by encoding latent images 1515 , 1520 , 1525 into visible image 1530 using techniques described herein. The color components of the second latent image 1525 introduce color variations in the encoded composite image 1530 because the content provided in the second latent image 1525 provides more variation than the content provided in the first latent images 1515 , 1520 . As shown in the decoded image 1540, when the encoded composite image 1530 is viewed through the decoder, the green component contributed by the second latent image 1525 varies with the red component contributed by the first latent image 1515 and the blue color contributed by the first latent image 1520. components combined. Thus, introducing the second latent image 1525 provides color variation and vivid color attributes to the encoded composite image 1530 . Those of ordinary skill in the art will recognize that more than two latent images may be provided for encoding into the visible image. Furthermore, one of ordinary skill in the art will recognize that changes to the underlying image may be introduced to any color component.

Digital decoding equipment for decoding and simultaneously displaying coded latent images having two or more color separations

When a composite image generated according to various embodiments of the present disclosure is printed or otherwise associated with an item, the component images used to generate the composite image can be viewed by applying a corresponding decoder. For example, a decoder may include a software decoder programmed to decode and simultaneously display two or more color separations corresponding to two or more component images. This article describes a sample software decoder. Component images can be visualized by using software-based decoders such as those described in U.S. Patent Nos. 7,512,249 ("the '249 patent") and 7,630,513 ("the '513 patent"), the entire disclosures of which are provided by incorporated by reference) can be viewed. As described in the '249 patent and the '513 patent, an image of an area where an encoded image is expected to appear may be captured using an image capture device such as a scanner, digital camera, or telecommunication device and decoded using a software-based decoder. In some embodiments, such software-based decoders can decode composite images by mimicking the optical properties of corresponding decoder lenses. A software-based decoder can also be used to decode digital versions of composite images of the invention not yet applied to articles.

According to one example, the latent image is divided into two or more color separations prior to embedding the latent image into the visible image. Two or more color separations of the latent image may correspond to colors not present in the visible image. Thus, each separation of the latent image can be encoded into a different separation of the visible image. For example, each color separation can be encoded individually into the visible image using the encoding techniques described herein.

度定向的线网屏来编码红分量；可以使用以

度定向的线网屏来编码绿分量；并且可以使用以

度定向的线网屏来编码蓝分量。如果使用双向网屏(例如，点网屏)，则两个潜在图像可以编码到一个网屏中并且相对于彼此以90度角定向。In an alternative example shown in FIG. 20 , latent image separations 2025 , 2027 , and 2029 may be encoded into multiple halftone screens positioned at different angles relative to horizontal line 2022 . These different angles are represented by line segments 2045 , 2047 and 2049 . The multiple halftone screens can be printed using the same color. For example, black ink can be used to print a line screen of the underlying image. Additionally, for a latent image with three separations, one can use

degree oriented line screen to encode the red component; you can use

degree oriented line screen to encode the green component; and can be used with

A highly oriented line screen to encode the blue component. If a bi-directional screen (eg, a dot screen) is used, two latent images can be encoded into one screen and oriented at a 90 degree angle relative to each other.

FIG. 20 shows a digitally encoded image 2010 comprising a visible image 2020 and a latent image with three corresponding color component separations 2025 , 2027 and 2029 . Visible image 2020 may be produced using black ink, grayscale, or multi-colored inks. Color component separations 2025 , 2027 and 2029 may be embedded in visible image 2020 . According to one example, color component separations 2025 , 2027 and 2029 may be encoded separately and then merged or embedded into visible image 2020 . Alternatively, processing may be performed such that the color component separations 2025, 2027 and 2029 are encoded at the time of embedding. In either case, the color component separations 2025 , 2027 and 2029 are not viewable to the naked eye without the software decoding device 2030 .

According to one example for embedding or merging a latent image with a visible image, the visible image may be sampled to produce a visible image having a first periodic pattern of a first predetermined frequency. The latent image having two color components is then mapped to the visible image such that the first periodic pattern of the visible image changes at locations corresponding to locations in the latent image having image content shown in two color components. The changes to the visible image are small enough that they are indistinguishable to the naked eye. However, when the software decoding device 2030 displays the encoded image at a frequency corresponding to the first predetermined frequency, the software decoding device 2030 captures a change in the visible image to display the latent image.

According to another method for embedding a latent image or merging a latent image with a visible image, a first periodic pattern is first imposed on the latent image with two color components instead of the visible image. In this case, a change is provided in the content associated with the underlying image having two color components. The latent image is then mapped to the visible image, and the content of the visible image is changed pixel by pixel based on the content of the encoded latent image. Other methods can be used to embed the latent image or merge the latent image with the visible image.

Software decoding device 2030 decodes latent images 2025, 2027, and 2029 while displaying encoded image 2010 on a graphical user interface ("GUI"). Digital decoding system 1800, described below and shown in FIG. 18, performs image processing and may be configured to assign a designated color to each latent image, including monochrome latent images. For example, three monochrome latent images may be provided within the visible image. The first monochrome latent image may be oriented at 15 degrees, the second monochrome latent image may be oriented at 30 degrees, and the third monochrome latent image may be oriented at 60 degrees. The software decoding device 2030 may be configured to detect the orientation of each monochrome latent image and assign corresponding color components to the color separations. Accordingly, the software decoding device 2030 may assign red to a first monochrome latent image oriented at 15 degrees, blue to a second monochrome latent image oriented at 30 degrees, and blue to a third monochrome latent image oriented at 60 degrees. Latent images are assigned green. The software decoding device 2030 may combine the specified colors to produce a composite color latent image for display to the user. For example, assigned colors can be combined to obtain a desired shade. One of ordinary skill in the art will recognize that any combination of colors may be used and any desired shade may be provided.

FIG. 21 illustrates an example digital decoding system 2100 for authenticating a coded image attached to an item. An encoder device 2110 is provided comprising an encoder module 2112 and an embedding module 2114 in communication with an encoding information database 2140 via a network 2120 . The encoder module 2112 and the embedding module 2114 are configured to perform encoding and embedding operations, respectively. The color coding module 2112 can also be programmed to generate a coded image to be attached to an item based on the coding parameters, the visible image, and the latent image. An encoder interface module 2150 is provided to serve as an interface between a user or document processing module (not shown) and the encoder device 2110 . Color coding module 2112 may be configured to store coding parameters, visible images and latent images in coding information database 2140 for subsequent use in authenticating digitally coded images.

Color encoding module 2112 may also store the encoded image in database 2140 and/or return the encoded image to encoder interface module 2150 . The color coding module 2112 may also provide the latent image to an embedding module 2114 adapted to embed the latent image into the visible image. The encoded image with the latent image embedded therein may be returned to the encoder interface module 2150 .

A software decoder or authenticator 2130 may include a decoding module 2132 and an authentication module 2134 that may communicate with an encoded information database 440 . The decoding module 2132 is adapted to obtain encoding parameters and/or encoded images from the encoding information database 2140 . The decoding module 2132 may use the encoding parameters to decode digitally encoded images. The decoding module 2132 may also be adapted to receive encoded images to be authenticated and to extract latent images. The latent image may be obtained from an authenticator interface 460 adapted to interface between the authentication requestor and the authenticator 2130 . After decoding the encoded image, the decoding module 2132 may return the decoded image to the authenticator interface and/or forward it to the authentication module 2134 . The authentication module 2134 is adapted to extract latent images from the decoded image for comparison with authentication criteria, which may be derived from a plurality of image features (e.g., shape descriptors, histograms, co-occurrence matrices, frequency descriptors, moments, color features, etc. ) export. The authentication module 2134 may also be adapted to determine an authentication result and return the result to the authenticator interface. The authentication module 2134 may include OCR software or barcode interpretation software to extract information from the item. Those of ordinary skill in the art should understand that the color coding module 2112, the embedding module 2114, the decoding module 2132, the authentication module 2134, the coding information database 2140, the encoder interface module 2150, and the authenticator interface module 2160 can be distributed in one or more data processing modules. device. For example, all of these elements could be located on a single user data processor. Alternatively, the various components of digital decoding system 2100 may be selectively communicatively distributed among multiple data processors via network 2120 .

Additionally, software-based decoders enable encoding of composite images using multiple color separations or geometrically complex element patterns. Some lens element patterns and shapes may be difficult or impractical to physically fabricate into optical lenses. However, these difficulties do not apply to the techniques used to create the images of the present invention, and furthermore do not apply to software-based decoders. Software-based decoders can be designed with flexibility to enable device users to adjust decoding parameters. The methods described herein can utilize "software lenses" having lens elements with variable frequency, complex and/or irregular shapes (including but not limited to ellipses, crosses, triangles, randomly formed closed curves, or polygons) , variable dimensions, or any combination of the preceding features. The method of the invention can be applied based on a particular lens configuration, even if it is not physically possible to manufacture that configuration. The methods described herein for creating composite images from component images are based on the inventive use of geometric transformations (eg, mapping, scaling, flipping, etc.) and do not require the creation of physical lenses for this purpose. Providing a software-based lens configuration or specification allows a user to implement a desired software lens. The software decoder can then use some or all of the properties of the software lens to decode the encoded composite image to produce decoded versions of the component images used to create the composite image.

The decoder may also include a rendering device configured to decode the latent image. The rendering device may include a lens configured in an arbitrary shape and having lens elements arranged in an arbitrary pattern. For example, a lens may include lens elements arranged in a symmetrical pattern, an asymmetrical pattern, or a combination of both. The lens may also include lens elements arranged in a regular pattern or an irregular pattern.

According to one example, the rendering device may include a pattern with a straight line pattern, a wavy line pattern, a zigzag pattern, a concentric ring pattern, a crosshatch pattern, an alignment point pattern, an offset point pattern, a grad frequency pattern, a target pattern, a herring A biconvex lens with a herring pattern or any other pattern arrangement of lenses. Alternatively, the rendering device may comprise a lens having a multi-dimensional pattern of lens elements, eg a fly's eye lens. Multidimensional patterns may include straight line patterns, square patterns, shifted square patterns, honeycomb patterns, wavy line patterns, zigzag patterns, concentric ring patterns, crosshatch patterns, alignment point patterns, offset point patterns, gradient frequency patterns, target patterns, herring pattern or any other pattern. Some examples of these decoding lenses are shown in FIG. 22 .

Those of ordinary skill in the art will readily appreciate that the present invention is suitable for a wide variety of uses and applications. Many other aspects of the invention, other than the embodiments described herein, will be apparent from or as reasonably suggested by the invention and the foregoing description of the invention without departing from the spirit or scope of the invention. Embodiments and changes, as well as numerous variations, modifications and equivalent arrangements.

While example embodiments of the present invention have been shown and described above, it should be understood that the invention is not limited to the constructions disclosed herein. The present invention may be embodied in other specific forms without departing from the spirit or attributes of the invention.

Claims (20)

1. one kind is encoded to the computer implemented method in visual picture based on coding parameter by latent image, latent image has two or more color components that simultaneously appear in the time that demoder is placed on coded image, demoder has the decoding parametric matching with coding parameter, and described method comprises:

Produce the first image being associated with the first color component via processor, the first pattern of the element of the corresponding color component processing based on providing in latent image is provided the first image;

Distribute the first angle to the first image;

Produce the second image being associated with the second color component, the second pattern of the element of the corresponding color component processing based on providing in latent image is provided the second image;

Distribute the second angle to the second image;

By aiming at the first image according to the first pattern of the first angle orientation element;

By aiming at the second image according to the second pattern of the second angle orientation element; And

By second doubling of the image of the first image of aiming at and aligning, to obtain coded image, coded image is visually similar to visual picture in the time utilizing naked eyes to watch.

2. computer implemented method according to claim 1, wherein, the first pattern of element and the second pattern of element configure according to the first coding frequency and the second coding frequency respectively.

3. computer implemented method according to claim 1, wherein, the first pattern of element and the second pattern of element are processed according to phase-shift operations.

4. computer implemented method according to claim 1, wherein, the first image of aiming at and second doubling of the image of aligning are comprised: overlapping with the second halftone screen that carries out patterning according to the second image by carry out the first halftone screen of patterning according to the first image.

5. computer implemented method according to claim 1, wherein, the first pattern of element comprises at least one in wavy texture, zigzag structure, fish-bone structure and arcuate structure.

6. computer implemented method according to claim 1, wherein, the second pattern of element comprises at least one in wavy texture, zigzag structure, fish-bone structure and arcuate structure.

7. computer implemented method according to claim 1, wherein, the first image and the second image are monotone images, and demoder distributes color component during decoding.

8. one kind is encoded to the computer implemented method in visual picture based on coding parameter by latent image, latent image has two or more color components that simultaneously appear in the time that demoder is placed on coded image, demoder has the decoding parametric matching with coding parameter, and described method comprises:

Obtain the latent image with at least two color components via processor;

Generation has the inverse video of the latent image of anti-color value;

Determine the pattern of latent image element for each color component of latent image, this pattern comprises at least one element frequency and the element arrangements corresponding with decoding parametric, and latent image element provides content information; And

Form coded image, coded image has the pattern of the latent image element including at least one element frequency corresponding with decoding parametric.

9. computer implemented method according to claim 8, also comprise: visual picture is carried out to screen processing to produce the half tone image of the visual picture that is wherein associated with latent image, wherein latent image can not be watched for naked eyes, but can watch by demoder in the time that demoder is placed on coded image.

10. computer implemented method according to claim 8, also comprise the first screen of the halftone pattern corresponding with the first color component, the first pattern of the first screen definition latent image element, to be included as the described at least first frequency of twice of at least one element frequency.

11. computer implemented methods according to claim 10, also comprise the second screen of the half tone image corresponding with the second color component, the second pattern of the second screen definition latent image element, to be included as the described at least second frequency of twice of at least one element frequency.

12. computer implemented methods according to claim 8, wherein, at least a portion of latent image element comprises the geometric configuration of at least one selection from polygon, ellipse, part ellipse, circle and part circular.

13. computer implemented methods according to claim 8, wherein, for each component image, the pattern of latent image element comprises at least one in wavy texture, zigzag structure, fish-bone structure and arcuate structure.

14. 1 kinds are encoded to the computer implemented method in visual picture based on coding parameter by two latent images, latent image has the different content being associated with two or more color components, the color effects appearing while demoder being placed on coded image to be created in, demoder has the decoding parametric matching with coding parameter, and described method comprises:

Produce the first image being associated with the first color component via processor, the first pattern of the element of the corresponding color component processing based on providing in latent image is provided the first image;

Produce the second image being associated with the second color component, the second pattern of the element of the corresponding color component processing based on providing in latent image is provided the second image, and the second latent image has the content different from the first latent image; And

By the first image and second doubling of the image, to obtain coded image, coded image is visually similar to visual picture in the time utilizing naked eyes to watch.

15. computer implemented methods according to claim 14, wherein, the first pattern of element and the second pattern of element configure according to the first coding frequency and the second coding frequency respectively.

16. computer implemented methods according to claim 14, wherein, the first pattern of element and the second pattern of element are processed according to phase-shift operations.

17. computer implemented methods according to claim 14, wherein, the first image of aiming at and second doubling of the image of aligning are comprised: overlapping with the second halftone screen that carries out patterning according to the second image by carry out the first halftone screen of patterning according to the first image.

18. computer implemented methods according to claim 14, wherein, the first pattern of element comprises at least one in wavy texture, zigzag structure, fish-bone structure and arcuate structure.

19. computer implemented methods according to claim 14, wherein, the second pattern of element comprises at least one in wavy texture, zigzag structure, fish-bone structure and arcuate structure.

20. computer implemented methods according to claim 14, wherein, have from the second latent image of the first latent image different content and present second color component different with the first color component.

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