TWI457921B - Holographic data storage system and image recognition method thereof - Google Patents

Description

Holographic storage system and image recognition method thereof

The present invention relates to an image storage system and an image recognition method, and more particularly to a holographic storage system and an image recognition method thereof.

At present, the main optical storage materials on the market are optical discs, including CD, DVD and BD. The data storage method is to burn binary data on the optical disc by focusing the laser light through the objective lens, so the storage capacity is limited. . In addition, most optical disc players read optical disc data in a point-to-point manner, which limits the data transmission rate. In recent years, a holographic storage system for page number storage has been proposed, so that the data storage device can have the advantages of high storage capacity and high transmission rate at the same time.

However, due to the aberrations and noise of the optical system in the holographic storage system, the image projected on the two-dimensional sensor is distorted, the brightness distribution is uneven, the spot and the Gaussian noise are not obtained, so that the correct image recognition cannot be achieved. Restore with images.

Therefore, the conventional techniques still have the above drawbacks and deficiencies to be solved.

One aspect of the present disclosure is to provide a holographic storage system including a storage medium, a sensor, and a processor. The storage medium is used to store the interference fringes corresponding to the original image. The sensor is disposed on the transmission path of the diffracted beam generated after the reference beam is incident on the storage medium, and is configured to receive the image pattern generated by the diffraction of the diffracted beam and convert the image information corresponding to the image pattern into the image signal. The processor is electrically coupled to the sensor for receiving the image signal, wherein the processor searches for the plurality of anchor points of the image pattern according to the number and arrangement pattern of the image pixels corresponding to the plurality of reference patterns in the database, and The plurality of regional patterns corresponding to the positioning points are sequentially compared with the reference pattern of the database to restore the original image.

In accordance with an embodiment of the present disclosure, the interference fringes are obtained by an interference effect between the object beam and the reference beam after encoding by the spatial modulator.

In accordance with an embodiment of the present disclosure, the object beam and the reference beam are coaxial or off-axis.

Another aspect of the present disclosure is to provide an image recognition method for a holographic storage system, comprising the following operational steps. First, build a database. Subsequently, an image signal is acquired. Then, searching for a plurality of anchor points of the image pattern corresponding to the image signal. Then, the plurality of area patterns corresponding to the positioning points are sequentially captured to perform structural similarity comparison with the plurality of reference patterns stored in the database. Thereafter, a reference pattern having the highest similarity to the area pattern is selected. The original image is then restored in accordance with the selected reference pattern.

According to an embodiment of the present disclosure, the number of image pixels corresponding to the area pattern and the reference pattern and the arrangement pattern are the same.

According to an embodiment of the present disclosure, the number and arrangement pattern of the image pixels corresponding to the area pattern and the reference pattern are adjustable.

According to an embodiment of the present disclosure, the arrangement pattern of the image pixels corresponding to the reference pattern includes any one of a cross, a cross, a circle, a triangle, a rectangle, a square, a diamond, and a polygon.

According to an embodiment of the present disclosure, the gray level level of the image pixel corresponding to the reference pattern is adjustable.

In accordance with an embodiment of the present disclosure, the reference patterns have different image encoding information between them.

According to an embodiment of the present disclosure, the method for searching for an anchor point includes any one of a gray scale weight method, a structural similarity positioning method, and a block center search method.

Therefore, the application of the present disclosure can reduce the full-frame original image by capturing the reference pattern having the highest similarity with the area pattern, thereby overcoming the problem that the sensor cannot perform image recognition due to image distortion and noise.

The spirit and scope of the present disclosure will be apparent from the following description of the preferred embodiments of the present disclosure. Modifications do not depart from the spirit and scope of the disclosure.

1 is a block diagram showing the structure of a holographic storage system 100 in accordance with an embodiment of the present disclosure. The hologram storage system 100 can include a storage medium 170, a sensor 180, and a processor 190. The encoded information of the original image stored in the storage medium 170 can be incident on the storage medium 170 through the reference beam 30 to generate a diffraction effect to project the image pattern on the sensor 180, and then received by the sensor 180 by the processor 190. The image pattern and the pre-established reference pattern are sequentially subjected to regional structural similarity (SSIM) operations and comparisons to restore the original image. In this embodiment, the sensor 180 can be a two-dimensional sensor for sensing full-frame image information.

In this embodiment, the holographic storage system 100 further includes a light source 110, a spatial filter 120, a first lens 131, a second lens 132, a third lens 133, a beam splitter 140, a spatial modulator 150, and a first mirror. 161, second mirror 162 and database 195. The image beam 10 having the original image information emitted by the light source 110 sequentially passes through the spatial filter 120, the first lens 131, and the beam splitter 140. The beam splitter 140 can divide the image beam 10 into an object beam 20 and a reference beam 30, wherein the object beam 20 is transmitted to the storage medium 170 via the spatial modulator 150, and the reference beam 30 is passed through the first mirror 161 and the second mirror 162. The reflection is transmitted to the storage medium 170 such that the object beam 20 and the reference beam 30 can create interference effects in the storage medium 170 to form interference fringes. The storage medium 170 can then store the interference fringes corresponding to the original image therein.

When the image information of the storage medium 170 is read, the reference beam 30 can be incident on the storage medium 170 to generate the diffracted beam 40. The sensor 180 is disposed on the transmission path of the diffracted beam 40 for receiving the image pattern generated by the diffraction of the diffracted beam 40, and converting the image information corresponding to the image pattern into an image signal. The processor 190 is electrically coupled to the sensor 180 for receiving image signals. The processor 190 can perform multiple positioning on the image pattern according to the number and arrangement of the image pixels corresponding to the plurality of reference patterns in the database 195. Searching for points, and sequentially comparing the plurality of regional patterns corresponding to the anchor points with the reference patterns of the database 195 to restore the original images.

In one embodiment of the present disclosure, the interference fringes are encoded by the object beam 20 incident spatial modulator 150, and the encoded object beam 20 can interfere with the reference beam 30 to obtain interference fringes. Therefore, the interference fringes have the encoded information of the spatial modulator 150 and the original image information.

In one embodiment of the present disclosure, the object beam 20 and the reference beam 30 are coaxial or off-axis. It should be noted that, in the holographic storage system 100 shown in FIG. 1, the object beam 20 and the reference beam 30 are arranged to be off-axis. In addition, the object beam 20 of the holographic storage system 100 and the reference beam 30 are more configurable to be coaxially coupled, and are not limited to the above embodiments.

2 is a schematic diagram showing a reference pattern setting of a database 195 in a hologram storage system 100 in accordance with an embodiment of the present disclosure. In this embodiment, the database 195 may include a first reference pattern 0000 to a sixteenth reference pattern 1111, wherein each of the reference patterns may be a 2x2 matrix and have four image pixels. In addition, all reference patterns can have different image coding information. That is, four image pixels in all reference patterns may have different permutations and combinations. For example, the first reference pattern 0000 is an image pixel having four black gray level levels, and the sixteenth reference pattern has four white gray level image pixels. It should be noted that the gray level level of the image pixel corresponding to the reference pattern can be adjusted according to actual operation requirements. Taking the 8-bit gray level as an example, the black gray level can be adjusted to 20 or 40, and the white gray level can be adjusted to 220 or 240 to meet the actual image brightness.

In an embodiment of the present disclosure, the arrangement pattern of the image pixels corresponding to the first reference pattern 0000 to the sixteenth reference pattern 1111 shown in FIG. 2 may be a matrix form of 2×2. In addition, the image pixels of the reference pattern may be arranged in any of a cross shape, a cross shape, a circle shape, a triangle shape, a rectangle shape, a square shape, a diamond shape, and a polygon shape, and are not limited to the above embodiments.

FIG. 3A is a schematic diagram showing an image pattern on the sensor 180 in the hologram storage system 100 according to an embodiment of the present disclosure. The image pattern may be an 8×8 matrix and includes first image pixels 301 to 64th image pixels 364. The processor 190 can search for the location points of the image pixels by using any one of a gray scale weighting method, a structural similarity positioning method, and a block center search method. For example, the image pixels of the above 8×8 matrix can find the center point of the first image pixel 301 as the first anchor point by the gray scale weight method. Then, according to the size of the reference pattern (for example, 2x2 matrix) established by the database 195, the first region pattern corresponding to the corresponding range of the first image pixel 301 is selected (by the first image pixel 301, the second image pixel 302, a ninth image pixel 309 and a 2x2 matrix pattern formed by the tenth image pixel). It should be noted that the number of image pixels corresponding to the image pixels corresponding to the area pattern and the reference pixels created by the database 190 are the same as the arrangement pattern, so as to facilitate structural comparison. In addition, if the number of image pixels of the area pattern is larger than the image pixel of the reference pattern, the reference pattern may be enlarged according to actual conditions to facilitate structural comparison between the area pattern and the reference pattern.

Then, the first region pattern and the first reference pattern 0000 to the sixteenth reference pattern 1111 established in the database 195 can be sequentially compared with the structural similarity. The manner of distinguishing the regional patterns can be referred to the third FIG. . FIG. 3B is a schematic diagram showing a region pattern on the sensor 190 in the hologram storage system 100 in accordance with an embodiment of the present disclosure. As can be seen from the above illustration, the first area pattern has the highest similarity to the ninth reference pattern 1000 of FIG. Then, the other region patterns are sequentially selected and the first reference pattern 0000 to the sixteenth reference pattern 1111 established in the database 195 are sequentially subjected to structural similarity comparison. The reference pattern having the highest similarity to the above-described area pattern may be used as a substrate after the above alignment process to replace the original area pattern, as shown in FIG. 3C. FIG. 3C is a schematic diagram showing a reference pattern having maximum similarity as a reduction substrate in a hologram storage system 100 according to an embodiment of the present disclosure. Then, the replaced area pattern and its constituent full-image image are decoded to restore the original image. It should be noted that the number and arrangement pattern of the image pixels corresponding to the area pattern and the reference pattern are adjustable. For example, the 8x1 rectangular matrix formed by the first image pixel 301 to the eighth image pixel 308 in FIG. 3A can be divided into the first region pattern, and the image pattern can be divided into eight by the top and bottom. The area pattern of the rectangular matrix, and the reference pattern in the database 195 can also be adjusted to an 8x1 rectangular matrix to facilitate structural comparison, and is not limited to the above embodiment.

4 is a flow chart showing an image recognition method of a holistic storage system 100 according to an embodiment of the present disclosure. The operation steps are described in an embodiment with reference to FIGS. 1 to 3C.

First, in operation step 410, a plurality of reference patterns, such as a first reference pattern 0000 to a sixteenth reference pattern 1111 having a matrix size of 2x2 as shown in FIG. 2, may be set in advance to create a database 195. Then, when the image data is read by the storage medium 170, the reference light beam 30 is incident on the storage medium 170 to generate a diffracted beam, and the diffracted beam is projected onto the sensor 180 and converted to obtain a corresponding image. The image signal is as shown in operation 420.

Then, in operation step 430, any one of the grayscale weighting method, the structural similarity positioning method, and the block center search method may be used to search for a plurality of positioning points in the image pattern corresponding to the image signal. For example, the center of the first image pixel 310 can be found as the first anchor point by the above search method.

In operation 440, the plurality of area patterns corresponding to the positioning points may be sequentially captured to perform structural similarity comparison with the plurality of reference patterns stored in the database. For example, the 2x2 matrix around the first image pixel 301 can be divided into the first region pattern (by the first image pixel 301, the second image pixel 302, the ninth image pixel 309, and the tenth image pixel 310). The pattern is composed), and then, the 8x8 image pattern is divided into 16 area patterns.

Next, the regional pattern is sequentially compared with the first reference pattern 0000 to the sixteenth reference pattern 1111 of the database 195 for structural similarity. The above structural similarity comparison uses the following operations:

Where x, y are the extracted area pattern and the reference pattern of the database, and C1 and C2 are adjustment parameters.

μ _x , μ _y are the mean intensity of the image of the area pattern and the reference pattern, respectively, and the formula is as follows:

σ _x , σ _y are the standard deviations of the image of the area pattern and the reference pattern, respectively, and the formula is as follows:

σ _xy is the correlation coefficient of the image of the area pattern and the reference pattern, and the formula is as follows:

It can be seen that after performing the above SSIM operation on each of the area patterns and the reference pattern in the database 195, a corresponding SSIM value can be obtained, and the SSIM value is compared with the brightness comparison of the images (contrast comparison, contrast ratio (contrast) Comparison) and structure comparison are associated. When the area pattern has a high similarity to the reference pattern, the SSIM value is relatively high to provide a basis for image comparison.

Thereafter, in operation 450, a reference pattern having the highest similarity to the area pattern is selected, as shown in FIG. 3C, as a base when the image is restored.

Then, in operation 460, the reference patterns 1000, 1011, 1010, 1001, ..., 1001 selected in FIG. 3C may be decoded to restore the original image.

Compared with the conventional method, in the above embodiments of the present disclosure, the structural similarity comparison method which is closer to the human eye recognition can be used, and the corresponding similarity of the regional images can be matched with the highest similarity comparison of the regional images. The reference image is used as the base of image restoration to overcome image distortion, uneven brightness distribution, spot and Gaussian noise, and achieve correct full-frame image restoration.

The steps mentioned in the present disclosure may be adjusted according to actual needs, except for the order in which they are specifically described, and may be performed simultaneously or partially simultaneously, without being limited to the above.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . Holographic storage system

110. . . light source

120. . . Spatial filter

131～133. . . First to third lenses

140. . . Beam splitter

150. . . Spatial modulator

161, 162. . . First mirror, second mirror

170. . . Storage medium

180. . . Sensor

190. . . processor

195. . . database

301~364. . . First image pixel - 64th image pixel

410～460. . . Steps

0000~1111. . . First reference pattern to sixteenth reference pattern

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a schematic structural diagram of a holographic storage system in accordance with an embodiment of the present disclosure.

2 is a schematic diagram showing a reference pattern setting of a database in a holographic storage system according to an embodiment of the present disclosure.

FIG. 3A is a schematic diagram showing an image pattern on a sensor in a holographic storage system according to an embodiment of the present disclosure.

FIG. 3B is a schematic diagram showing a region pattern on a sensor in a holographic storage system according to an embodiment of the present disclosure.

FIG. 3C is a schematic diagram showing a reference pattern having the greatest similarity as a reduction substrate in a holographic storage system according to an embodiment of the present disclosure.

4 is a flow chart showing an image recognition method of a holographic storage system in accordance with an embodiment of the present disclosure.

410～460. . . Steps

Claims (10)

A holographic storage system includes: a storage medium for storing an interference fringe corresponding to an original image; and a sensor disposed in a transmission path of a diffracted beam generated after a reference beam is incident on the storage medium Receiving an image pattern generated by the diffraction of the diffracted beam and converting the image information corresponding to the image pattern into an image signal; and a processor electrically coupled to the sensor for receiving The image signal, the processor performs a plurality of positioning points on the image pattern according to the number and arrangement pattern of the image pixels corresponding to the plurality of reference patterns in a database, and the plurality of area patterns are arranged around the positioning points. And sequentially comparing the regional patterns with the reference patterns of the database for structural similarity to select the reference patterns having the highest similarity with the regional patterns for restoring the original image. The holographic storage system of claim 1, wherein the interference fringes are obtained by an object beam being encoded by a spatial modulator and having an interference effect with the reference beam. The holographic storage system of claim 2, wherein the object beam and the reference beam are coaxial or off-axis. An image recognition method for a holographic storage system, comprising: Establishing a database; acquiring an image signal; searching for a plurality of positioning points of the image pattern corresponding to the image signal; sequentially capturing a plurality of regional patterns corresponding to the positioning points to be associated with the database And storing a plurality of reference patterns for performing a structural similarity comparison; selecting the reference patterns having the highest similarity with the area patterns; and restoring an original image according to the selected reference patterns. The image recognition method of the holographic storage system of claim 4, wherein the number of the image pixels corresponding to the reference patterns and the arrangement pattern are the same. The image recognition method of the holographic storage system of claim 5, wherein the number of the image pixels corresponding to the area patterns and the reference patterns and the arrangement pattern are adjustable. The image recognition method of the holographic storage system according to claim 6, wherein the arrangement pattern of the image pixels corresponding to the reference patterns comprises a cross, a cross, a circle, a triangle, a rectangle, a square, a diamond, and a polygon. Either. The image recognition method of the holographic storage system of claim 4, wherein the grayscale levels of the image pixels corresponding to the reference patterns are adjustable. The image recognition method of the holographic storage system of claim 4, wherein the reference patterns have different image coding information. The image recognition method of the holographic storage system of claim 4, wherein the method for searching the anchor points comprises any one of a gray scale weighting method, a structural similarity positioning method, and a block center search method.