JP2011091539A - Image processor, image processing method, program for executing the image processing method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the stability of decoding because scan data is input in a state disadvantageous for decoding when scanning and decoding of a pattern representing additional information is performed in the MFP.
SOLUTION: Operation means for giving instructions for executing scanning and decoding of a document with a code pattern, and means for switching scanner settings and image processing settings to settings dedicated to code pattern processing when instructed by the operation means It is characterized by having. Dedicated settings mean that the brightness at the time of reading by the scanner is darker than that for general document reading, the reading resolution is fixed to a specified value, the code pattern is emphasized by edge enhancement and color processing, and image information unnecessary for decoding is displayed. This is to increase the amount of image processing settings to be eliminated and to secure the memory capacity in the system for job execution, and to minimize the compression at the time of primary storage of the image data being processed.
[Selection] Figure 9

Description

  The present invention relates to an image processing apparatus that handles a code image pattern such as a two-dimensional code and a barcode, an image processing method, a program for executing the image processing method, and a storage medium.

  A technique is known in which additional information is printed on paper as a predetermined dot pattern in addition to the original document image when printing the document (see, for example, Patent Documents 1 to 3). In this additional information, for example, security information (user name, print date, etc.) of the printed document, restriction information on how to handle the document (copy permission / prohibition, etc.), audio information, and the like are embedded. A technique is also known in which a paper document on which additional information is printed is read by a scanner or the like, and a pattern representing the additional information is detected and analyzed from the image data to obtain additional information and used for device control or the like ( For example, see Patent Document 4). At this time, there are cases where it is possible to detect a pattern representing additional information from an image captured under the same conditions as when capturing a general image that is not additional information, but a dedicated process for reading the pattern is required. There is also a usage form. For example, Patent Document 5 discloses a technique for switching between a normal image capturing mode and a barcode-dedicated image capturing mode to improve operability for barcode image acquisition and barcode recognition.

JP 2002-305646 A JP 2006-005399 A JP 2008-271110 A JP 2008-227930 A JP 2004-056696 A

  However, the quality of the pattern representing the additional information being printed may be deteriorated due to the printing state, storage state, paper characteristics, etc., or depending on the characteristics of the scanner used to read it, it can be obtained by reading. Some image data is not suitable for decoding.

  When an image is read using a scanner installed in an MFP (multifunction printer) and additional information is decoded by a decoder built in the MFP, it is required to acquire image data suitable for decoding more stably. This is because the operation while checking the scanned image data on the spot is not practical for an MFP that does not have a high-quality preview function.

Image reading means (200) for scanning a document and acquiring digital image data;
First image processing means (150) for converting the image data acquired by the image reading means;
A decoding unit (128) for detecting a code image pattern from the image data acquired by the image reading unit or the image data converted by the first image processing unit and performing a decoding process;
First operating means (410) for instructing to scan a document and decode a coded image;
A reading setting switching means (S9-02) for switching the setting of the image reading means to a default code image reading setting when the first operation means is instructed to process the code image;
A second image processing unit (S9-04) for performing a conversion process different from that of the first image processing unit when instructed to process the code image by the first operation unit; An image processing apparatus (001)
The reading setting switching means is a means for switching at least two modes of a general image reading mode and a code image reading mode, and the code image reading mode includes at least the following setting.

  Fix the resolution to the default value.

  The gradation reproducibility of the bright part of the original is set higher than in the general image reading mode.

  The second image processing means includes at least one of the following processes.

  Spatial filtering for edge enhancement.

  Lookup table processing for emphasizing gradation near the read value of the code image pattern.

  Lookup table processing for reducing the amount of signal value information not included in the vicinity of the read value of the code image pattern.

  A process of setting the image data compression rate in the system to be lower or non-compressed than in the general image reading mode, and securing more memory for executing the code image reading and decoding at the same time than in the general image reading.

  In order to decode additional information with a decoder built in the MFP, when scanning a document with a pattern representing additional information, it is necessary to change other settings by having an operation means for instructing the operation. The operability is improved. Also, by having means for switching the setting of the scanner and the setting of the image processing performed inside the MFP to the most suitable setting for reading and decoding the additional information when receiving the instruction, it is possible regardless of the pattern quality on the document. A highly accurate decoding result can be obtained. Furthermore, the setting for obtaining a high-precision decoding result is automatically performed inside the MFP, so that the decoding failure rate is reduced and the burden on the user such as re-operation is reduced.

Digital MFP suitable for applying this embodiment Control system configuration of a digital multi-function peripheral suitable for applying this embodiment Diagram showing tile data conceptually Configuration diagram of the scanner image processing unit Configuration diagram of the printer image processing unit 2D code manuscript example Operation screen example 1 for code analysis Operation screen example 2 for code analysis The flowchart which shows the process of Example 1. The flowchart which shows the process of Example 2. Example of scanned image with normal settings Scanned image example with code analysis settings Example of image data after image processing for code analysis

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows the appearance of a digital multi-functional peripheral 001 that is suitable for applying this embodiment.

  A scanner unit 200 shown in FIG. 1 illuminates an image on paper as an original, and is a three-line CCD provided with color filters (not shown) of R (red), G (green), and B (blue) or BK (black). 4 line CCD to which () is added is scanned. The charge amount obtained by the CCD is converted into an electrical signal representing RGB color image data or / and gray scale image data. When a document is set on the tray 202 of the document feeder 201 and a reading start instruction is given from the operation unit 400, the CPU 103 gives an instruction to the scanner 200, and the feeder 201 feeds the document one by one and performs a document image reading operation.

  The printer unit 300 shown in FIG. 1 is a part that converts raster image data into an image on paper. The printing method includes an electrophotographic method and an ink jet method, but is not particularly limited in this embodiment. Activation of the printing operation is started by an instruction from the controller CPU 103. The paper cassette 302 is a part that is set for feeding paper to the printer, and may have a plurality of paper feed stages so that different paper sizes or different paper orientations can be selected. The paper discharge tray 303 receives paper that has been printed.

  FIG. 2 is a block diagram for explaining the configuration of the controller 100 of the digital multifunction peripheral 001 in more detail.

  The controller 100 is electrically connected to the scanner unit 200 and the printer unit 300. On the other hand, the controller 100 is connected to a computer (not shown) and other external devices via the LAN 500 and WAN 600. As a result, external image data and device information can be input and output.

  The CPU 103 comprehensively controls access to various connected devices based on a control program or the like stored in the ROM 108, and also comprehensively controls various processes performed in the controller. The RAM 107 is a system work memory for the operation of the CPU 103 and also a memory for temporarily storing image data. The RAM 107 includes an SRAM that retains stored contents even after the power is turned off, and a DRAM that erases the stored contents after the power is turned off. The ROM 108 stores a boot program for the apparatus. An HDD 109 is a hard disk drive, and can store system software and image data.

  The operation unit interface 104 is an interface unit for connecting the system bus 101 and the operation unit 400. The operation unit interface 104 receives image data to be displayed on the operation unit 400 from the system bus 101 and outputs the image data to the operation unit 400 and outputs information input from the operation unit 400 to the system bus 101.

  A network interface 105 is connected to the LAN 500 and the system bus 101 to input / output information. The modem 106 is connected to the WAN 600 and the system bus 101 and inputs / outputs information. A binary image rotation unit 116 converts the direction of binary image data before transmission. The binary image compression / decompression unit 117 converts the resolution of the binary image data before transmission into a resolution that matches a predetermined resolution or partner capability. For compression and expansion, methods such as JBIG, MMR, MR, and MH are used. The image bus 102 is a transmission path for exchanging image data, and is configured by a PCI bus or IEEE1394.

  The scanner image processing unit 150 corrects, processes, and edits image data received from the scanner unit 200 via the scanner interface 113. Details of processing performed by the scanner image processing unit 150 will be described later.

  The compression unit 112 receives the image data and divides the image data into blocks of 32 pixels × 32 pixels. The 32 × 32 pixel image data is referred to as tile data. FIG. 3 conceptually represents this tile data. In a document (paper medium before reading), an area corresponding to the tile data is referred to as a tile image. The tile data is added with the average luminance information in the 32 × 32 pixel block and the coordinate position of the tile image on the document as header information. Further, the compression unit 112 compresses image data including a plurality of tile data. The decompression unit 114 decompresses image data composed of a plurality of tile data, rasterizes the data, and sends the raster data to the printer image processing unit 160.

  The printer image processing unit 160 receives the image data sent from the decompression unit 114 and performs image processing. The image data after image processing is output to the printer unit 300 via the printer interface 115. Details of processing performed by the printer image processing unit 160 will be described later.

  The image conversion unit 120 performs a predetermined conversion process on the image data, and includes a processing unit as described below.

  The decompression unit 121 decompresses the received image data. The compression unit 122 compresses the received image data. The rotation unit 123 rotates the received image data. The scaling unit 124 performs resolution conversion processing (for example, 600 dpi to 200 dpi) on the received image data. The color space conversion unit 125 converts the color space of the received image data. The color space conversion unit 125 further performs a known LOG conversion process (RGB → CMY) and a known output color correction process (CMY → CMYK). The binary multi-value conversion unit 126 converts the received two-gradation image data into 256-gradation image data. Conversely, the multi-level binary conversion unit 127 converts the received 256-gradation image data into 2-gradation image data using a technique such as error diffusion processing.

  The code image processing unit 128 performs code image pattern processing. A process of generating a predetermined code image and detecting the code image pattern from the received image data and decoding it to acquire original information is performed.

  The thinning unit 129 performs resolution conversion by thinning out the pixels of the received image data.

  The synthesizer 130 synthesizes the received two image data to generate one piece of image data. When combining two pieces of image data, a method of using an average value of luminance values of pixels to be combined as a combined luminance value, or a luminance value of a pixel having a brighter luminance level, A method for obtaining a luminance value is applied. In addition, it is possible to use a method in which the darker pixel is used as a synthesized pixel. Furthermore, a method of determining a luminance value after synthesis by a logical sum operation, a logical product operation, an exclusive logical sum operation, or the like between pixels to be synthesized is also applicable. These synthesis methods are all well-known methods.

  The RIP 110 receives intermediate data generated based on PDL code data transmitted from the computer 002 or the like, and generates multi-value bitmap data.

  FIG. 4 is a block diagram illustrating a detailed configuration of the scanner image processing unit 150.

  151 is a sub-scanning color misregistration correction unit that corrects color misregistration in the sub-scanning direction of the input image (RGB sub-scanning direction misalignment). For example, 1 × 5 size matrix calculation is performed for each color of image data. Processing to be performed is performed.

  Reference numeral 152 denotes a main scanning color misregistration correction unit that corrects color misregistration in the main scanning direction of the input image (main scanning direction misregistration for each of the RGB versions). For example, 5 × 1 matrix calculation is performed for each color of image data. Processing to be performed is performed.

  Reference numeral 153 denotes an input color correction unit that corrects the color of the input image. The input color correction unit 153 converts image data including characteristics unique to the scanner into standard data. For example, the color space of the input image is changed to an arbitrary color. Perform processing to convert to space.

  An image area determination unit 154 identifies an image type in the input image. For example, pixels constituting each image type such as a photographic part / character part, chromatic part / achromatic part, etc. in the input image are identified, and attribute flag data indicating the type is generated on a pixel basis.

  Reference numeral 155 denotes a filter processing unit that arbitrarily corrects the spatial frequency characteristics of the input image. For example, 7 × 7 matrix calculation is performed.

  A histogram processing unit 156 samples and counts image signal data in the input image. For example, it determines whether the input image is a color or a monochrome image and determines the ground color level of the input image.

  The processing in the scanner image processing unit 150 is not limited to the processing using all of the sub-scanning color misregistration correction unit 151 to the input color correction unit 156 described above, and other image processing modules may be added. , May be deleted. Furthermore, the processing order of the sub-scanning color misregistration correction unit 151 to the input color correction unit 156 is not limited to this.

  FIG. 5 is a block diagram illustrating a detailed configuration of the printer image processing unit 160.

  Reference numeral 161 denotes a ground color removing unit that removes the ground color of image data, that is, unnecessary background fogging. For example, the background color removal processing is performed by a matrix operation of 3 × 8 size or a one-dimensional lookup table (LUT).

  A monochrome generation unit 162 converts color image data to monochrome data and converts color image data, for example, RGB data to gray (Gray) single color when printing as a single color. For example, RGB is multiplied by an arbitrary constant to perform a 1 × 3 size matrix calculation as a gray signal.

  Reference numeral 163 denotes an output color correction unit that performs color correction in accordance with the characteristics of the printer unit 300 that outputs image data. For example, processing by 4 × 8 size matrix calculation or direct mapping is performed.

  Reference numeral 164 denotes a filter processing unit that arbitrarily corrects the spatial frequency characteristics of the image data. For example, 7 × 7 size matrix calculation processing is performed.

  Reference numeral 165 denotes a gamma correction unit that performs gamma correction in accordance with the characteristics of the output printer unit 300, and generally uses a one-dimensional lookup table (LUT).

  Reference numeral 166 denotes a non-linear processing unit that performs a process for suppressing the amount of toner used when the toner saving mode is effective, in addition to the show-through prevention process.

  Reference numeral 167 denotes a pseudo halftone processing unit that performs arbitrary pseudo halftone processing in accordance with the number of gradations of the printer unit 300 to output, and performs arbitrary screen processing such as binarization and binarization and error diffusion processing. .

  The processing in the printer image processing unit 160 is not limited to the processing using all of the ground color removal unit 161 to the pseudo halftone processing unit 167 described above, and other image processing modules may be added. And may be deleted. Furthermore, the processing order of the ground color removal unit 161 to the pseudo halftone processing unit 167 is not limited to this order.

  In this embodiment, LVBC (Low Visibility Barcode) disclosed in Japanese Patent Laid-Open No. 2008-271110 is cited as an example of a code image to be handled. FIG. 6 is an enlarged view of an example of a document image to which LVBC is added and a part thereof. As shown in this figure, in a typical usage mode, fine dots are arranged on the entire document in order to represent encoded information.

  In order to read and decode the added information, it is necessary to accurately read such fine dots and convert them into image data. However, when a document is scanned by the scanner 200 mounted on the MFP, characteristics such as illumination for illuminating the document, a sensor for detecting reflected light from the document and converting it into an electrical signal, and surface characteristics of the document, etc. For this reason, fine dots are often read thinner than actual. It is difficult to accurately detect fine dots in the thinly read image data, and the processing described below is effective for improving the stability of decoding.

  7 and 8 are screens displayed on the display device on the operation unit 400 in order to operate the dot information analysis application. When the dot information analysis start button 411 in FIG. 7 or the start button 423 in FIG. 8 is pressed by the user, the CPU 103 starts an operation for starting analysis scan and control processing.

  The black dot analysis button 421 and the magenta dot analysis button 422 in FIG. 8 are for the user to select in advance the dot color of the code to be analyzed. Details of internal processing when a color is designated will be described later.

  FIG. 9 is a flowchart showing the flow of processing of this embodiment.

  When a scan start command is transmitted to the CPU 103 by a user operation, it is determined in step S9-01 whether the command is a dot information analysis job. If it is determined that the job is not an analysis job, the process proceeds to step S9-07 because the job is a normal copy job. If it is an analysis job, the process proceeds to step S9-02, and the scan setting is changed to that dedicated to the analysis job. Here, in order not to lose the gradation of the bright part of the document, the shading coefficient is changed, a setting for acquiring a darker image than the normal scan image is performed, and the scan resolution is fixed at, for example, 600 × 600 dpi. FIG. 11 shows an example of scanning an LVBC document with normal settings, and FIG. 12 shows an example of scanning the same document with reading settings darker than normal. In response to a command from the CPU 103, the scan setting is notified to the controller built in the scanner unit 200 through the scanner I / F 113, and a scan operation is performed accordingly (step S9-03). The image data thus acquired is transmitted to the scanner image processing unit 150, and image processing suitable for analysis is performed (step S9-04). Details of this image processing will be described later. Next, the process proceeds to step S9-05, where analysis and decoding processing are performed in the code image processing unit 128. As this internal process, for example, a process as disclosed in Japanese Patent Application Laid-Open No. 2008-211332 is applied. In step S9-06, the decoding result is received, and data to be presented to the user is created by the CPU 103 and displayed on the display device on the operation unit 400. In some cases, the data may be processed via the printer image processing unit 160 and printed out by the printer 300.

  Next, the image processing dedicated to analysis performed in step S9-04 will be described.

  The scanner image processing unit 150 performs the following dedicated processing.

  The sub-scanning color misregistration correction unit 151 and the main scanning color misregistration correction unit 152 perform processing equivalent to that during normal scanning.

  In the input color correction unit 153, a process for improving the gradation near the signal value obtained when scanning fine dots printed on white paper, and a signal value clearly different from the dot color to be decoded The process to replace with the value is performed by direct mapping.

  In the process of improving the gradation, the number of output signal steps in a signal area having a high probability of being input as a fine dot reading value is expanded, and instead, the number of steps in a signal area that is not a fine dot reading value is compressed.

  As part of this, processing for replacing all signals in unnecessary color gamut with signal values equivalent to white is also performed. Estimate the fine dot reading range when R, G, B misregistration is within the expected range, and replace colors outside that range (for example, pure red or blue) with white To do. When there are a plurality of possible dot colors to be input, an estimated range of dot reading values is set for each color, and only a color gamut that does not fall under any of these ranges is to be replaced with white. As shown in FIG. 8, when the black dot analysis button 421 and the magenta dot analysis button 422 are on the operation screen, a default range for each specified dot color is stored separately and used according to the specification. To reflect in the direct mapping coefficient.

  The above processing executed by the input correction unit 153 is realized by changing the direct mapping coefficient. As the method, there are a method of storing a plurality of coefficients in the HDD 109 and switching each time, a method of storing data for coefficient calculation in the HDD 109 and calculating and setting the direct mapping coefficient by the CPU 103 according to the conditions. .

  Since the processing as described above is performed, the image output from the input color correction unit 153 is destroyed in the image other than the fine dots.

  The image area determination unit 154 is not used here. The filter processing unit 155 applies strong edge enhancement processing to enhance the contrast of the fine dots left by the above processing.

  The histogram processing unit 156 is basically not used in the present embodiment, but in some cases, a histogram of signal values is acquired in order to calculate a coefficient for correcting the remaining dots.

  FIG. 13 shows an example of image data after such processing.

  Many MFPs have a mechanism for increasing the size of the image data by compressing the image data in the system in order to increase the opportunity to handle large image data and to control various functions simultaneously. Even when image quality sufficient for normal copying and printing is maintained, this compression may affect the decoding stability when the code image is scanned and decoded. In the present embodiment, a process when a code image analysis job is generated will be described.

  FIG. 10 is a flowchart showing the flow of processing of this embodiment. If it is determined in step S10-01 that the job is an analysis job, in step S10-02, among the jobs processed in parallel in the system, jobs that can be paused are temporarily stopped. In step S10-03, a memory for an analysis job is secured. Since this memory is also used as a buffer for holding image data, a larger size than that of a normal job is secured. Thereby, it is possible to lower the compression rate when images are stored in the RAM 107 and the HDD 109 than in a normal job, or to store the images in an uncompressed state. Then, the decoding process described in the first embodiment is performed on an image stored with higher image quality than usual (step S10-04). When the decoding is completed, in step S10-05, the memory reserved for the analysis job is released, and the series of processes is ended.

Claims (7)

Image reading means (200) for scanning a document and acquiring digital image data;
Image processing means (150) for converting the image data acquired by the image reading means;
Decoding means (128) for detecting a code image pattern from image data including the code image pattern and performing a decoding process;
Code image analysis image processing means (S9-04) for converting the image data into characteristics suitable for analysis by the image processing means before inputting the image data including the code image pattern to the decoding means. ,
First operating means (410) for instructing to scan a document and decode a coded image;
A reading setting switching unit (S9-02) for switching the setting of the image reading unit to a predetermined code image reading setting when an instruction to process the code image is given by the first operation unit;
An image processing apparatus comprising: an image processing switching unit (S9-04) for applying the code image analysis image processing unit when the first operation unit is instructed to process the code image. (001). 2. The reading setting switching means is means for switching at least two modes of a general image reading mode and a code image reading mode, and the code image reading mode includes at least the following setting. An image processing apparatus according to 1.
Fix the resolution to the default value.
The gradation reproducibility of the bright part of the original is set higher than in the general image reading mode. The image processing apparatus according to claim 1, wherein the code image analysis image processing means includes at least one of the following processes.
Spatial filtering for edge enhancement.
Lookup table processing for emphasizing gradation near the read value of the code image pattern.
Lookup table processing for reducing the amount of signal value information not included in the vicinity of the read value of the code image pattern.
A process of setting an image data compression rate in the system to be lower or non-compressed than usual, and simultaneously securing more memory for executing the code image reading and decoding than when reading a general image.   The image processing apparatus according to claim 1, wherein the first operation unit further includes a second operation unit for designating a color of a code image to be decoded.   4. The image processing apparatus according to claim 1, further comprising storage means for preliminarily storing, for each color of the code image, information for determining the vicinity of the read value of the code image pattern. .   6. The image processing apparatus according to claim 1, further comprising means for resetting the look-up table in accordance with information for setting a vicinity of a read value of the code image pattern. An image reading step for obtaining digital image data by scanning a document;
An image processing step for converting the image data acquired in the image reading step;
A decoding step for detecting and decoding the code image pattern from the image data including the code image pattern;
Before inputting image data including a code image pattern into the decoding step, an image processing step for code image analysis for converting the image data into characteristics suitable for analysis in the image processing step;
A first operation step for instructing to scan a document and decode a coded image;
A reading setting switching step for switching the setting of the image reading step to a default code image reading setting when a code image processing is instructed in the first operation step;
An image processing means comprising: an image processing switching step for applying the code image analysis image processing step when an instruction to process the code image is instructed in the first operation step.

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