KR100578185B1 - Device and method for detecting recording image's unmatching in the holographic digital data system - Google Patents

Abstract

The present invention relates to a non-matching measurement apparatus of a reproduced image in a holographic digital data system and a method thereof. In particular, the method of the present invention is applied to a storage medium by irradiating the storage medium with a reference light at the same angle as the data recording of the storage medium. Reproducing the recorded data, photographing the image reproduced from the storage medium through the CCD array, detecting the light intensity of each CCD pixel signal captured by the CCD array, and the light according to the detected light intensity Intersecting the intensity curve with the preset reference value and measuring the position value of the intersected point; comparing the measured position value with the set value and freezing between the pixel of the reproduced image and the pixel of the CCD array according to the comparison result. Determining whether it is in or miss aligned. Therefore, the present invention detects the light intensity in an image output through the CCD, measures the position value of the point intersecting the light intensity curve according to the detected light intensity and the reference value, and compares the measured position value with the set value. Therefore, the alignment or miss alignment between the pixels of the reproduced image and the pixels of the CCD array can be accurately determined.

Holographic digital data systems, reproducing images, CCD arrays, miss alignment

Description

Non-matching measurement apparatus of reproduced image in holographic digital data system and its method {DEVICE AND METHOD FOR DETECTING RECORDING IMAGE'S UNMATCHING IN THE HOLOGRAPHIC DIGITAL DATA SYSTEM}

1 is a block diagram of a typical holographic digital data system,

2 is a view showing one page image information reproduced from a storage medium in a conventional holographic digital data system;

3 is a block diagram showing a reproduction device of a holographic digital data system to which the present invention is applied;

4 is a block diagram showing a mismatch detection apparatus of a reproduced image of a holographic digital data system according to the present invention;

5 is a flowchart illustrating a mismatch detection method of a reproduced image of a holographic digital data system according to the present invention;

6A to 6D are graphs showing changes in the CCD pixel level of an edge frame in a reproduced image and graphs for misalignment measurement between the reproduced image and the CCD pixel by detecting the light intensity of the CCD pixel according to the present invention.

<Description of the code | symbol about the principal part of drawing>

124: storage medium 128: CCD array

130: reproduced image 140: signal processing unit

141: input unit 143: light intensity detection unit

145: detection image buffer 147: misalignment measuring unit

149: CPU

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic digital data storage system (HDDS), and more particularly, to an apparatus and method for measuring mismatches of reproduced images in a holographic digital data system.

Recently, technologies for storing holographic digital data have been actively researched in various fields, for example, thanks to remarkable developments such as semiconductor lasers, charge coupled devices (CCDs), and liquid crystal displays (LCDs). As a result, fingerprint recognition systems for storing and reproducing fingerprints have been put to practical use, and are being expanded to various fields that can apply the advantages of large storage capacity and ultra-high data transfer speed. Among them, a holographic digital data system storing a large amount of data is a storage medium, for example, optical refraction, in which an interference fringe generated when the signal light from the target object and the reference light are interfered with each other is sensitive to the amplitude of the interference fringe. By recording to a storage medium such as a photorefractive crystal, it is possible to display a three-dimensional image of an object, and also to display hundreds to thousands of hologram data composed of pages of binary data. Can be stored in place.

1 is a block diagram of a general holographic digital data system. Referring to FIG. 1, a general holographic digital data system is installed at a position corresponding to a light source 12 and a light source 12 for generating a laser light, so that the light of the light source 12 is referred to as a reference beam and a signal beam. a beam splitter 18 separating the beam into a beam, a mirror 32 reflecting the reference light separated from the light splitter 20, and light reflected from the mirror 32 is incident on the storage medium 10. Spatial Light Modulator (SLM) that carries input data, that is, binary data of a plurality of pixels configured in units of pages, on the signal light separated by the rotating mirror 36 and the optical separator 20 for converting the angles to be converted. (26), the interference fringe generated by the interference of the signal light output from the spatial light modulator (SLM) 26 and the reference light reflected by the rotation mirror 36 is recorded and diffracted and outputs the interference fringe recorded by irradiation of the reference light. Storage medium 10, write to storage medium 10 And a CCD 42 for reproducing a one-page binary pixel data image recorded in the form of an interference fringe on the storage medium by irradiating quasi-light only, and converting the reproduced data image into electrical data and outputting the same. Unexplained reference numeral 14 denotes an optical magnification lens, 34 denotes a retardation lens, and 30 and 40 denote Fourier lenses.

The holographic digital data system thus constructed operates as follows.

The laser light irradiated from the light source 12 is divided into reference light and signal light in the light separator 18. At this time, the signal light is input to the spatial light modulator 26 and modulated. That is, the signal light is incident on the storage medium 10 after the data input from the spatial light modulator 26 is modulated in units of one page of the binary data of the intensity of real pixels. In addition, the reference light is incident on the storage medium 10 at an angle changed by the rotation mirror 36. That is, the reference light which slightly changes the angle of the rotation mirror 36 corresponding to each page is incident on the storage crystal which is the storage medium 10. The signal light and the reference light cause interference inside the storage medium 10 for recording the hologram, and light-induced generation of mobile charge of the internal kinetic charge of the storage medium 10 according to the intensity of the interference fringe generated at this time. Is generated and an interference fringe is recorded through this process.

In order to read the data recorded in the storage medium 10, only the reference light needs to be irradiated to the storage medium 10. That is, when the reproduction reference light having the same deflection angle as the deflection angle of the recording reference light enters the storage medium 10 on which the interference data is recorded, the reproduction reference light is diffracted to make a single page of binary data (consisting of the original pixel contrast ( That is, the checkerboard pattern) is restored. The binary data (one page unit) reproduced from the storage medium 10 is restored to the original data through the CCD 42, the signal processing unit (not shown), the decoder (not shown), and the like.

In the related art, in order to restore the image data in units of pages reproduced from the storage medium 10, that is, binary pixel data, to the original data through the CCD 42 or the like, a signal matching process of 1: 1 matching has been performed. That is, the pixel of the image reproduced in the storage medium 10 and the pixel of the CCD 42 array are matched 1: 1 to restore original pixel data. However, in a shift multiplexing system employing 1: 1 pixel matching, when the size error between the reproduced image and the CCD pixel is 1/2 of the CCD pixel size, serious degradation occurs in the data detected by the CCD 42 array. As a result, the stored data cannot be obtained correctly.

To prevent this, one pixel of the reproduced image of the storage medium 10 is replaced by n × n (n ≧ 2) such as four pixels (2 × 2) or nine (3 × 3) of the CCD 42 array. The technology of oversampling and restoring only the center pixel data to the original data has emerged. More specifically, the N × N (eg 240 × 240) hologram data recorded on the storage medium 10 is encoded, decoded by inserting a series of preprocessing (e.g., error correction codes (parity bits), etc.). After the frame is encoded by the edge frame generation process for oversampling, the signal is modulated into signal light by the spatial light modulator 26 and recorded in the storage medium 10. N × N (eg, 240 × 240) hologram data reproduced from the storage medium 10 are irradiated onto the CCD, and a plurality of CCD arrays are reproduced images having a size of (N + M) × (N + M) (eg, 1024 ×). 1024) and oversampling a series of pixels of the captured playback image into one pixel to convert the original N × N size image (e.g., 240 × 240), and then perform an ECC (Error Correction Code) process. Restore the original data via

FIG. 2 is a diagram illustrating one page image information reproduced in a storage medium in a conventional holographic digital data system. Referring to FIG. 2, when one page information reproduced from a storage medium in a conventional holographic digital data system has a size of, for example, 1024 × 1024, a data area 100 of 720 × 720 is present in a central portion of a page. A frame area 200 in which pixels are always on exists in the outer portion of the page, which is the periphery of the data area, and is used as information for separating the data area. That is, when one pixel of a reproduced image of a storage medium is oversampled by nine pixels of an n × n (e.g., 3x3) CCD array, only a pixel of the reproduced image corresponding to the data region excluding the frame region is a 3x3 CCD. You will oversample into an array.

However, in the holographic digital data system according to the prior art, despite the above oversampling method, a misalignment occurs between the pixels of the reproduced image and the pixels of the CCD array due to the interference effect between the pixels, thereby restoring normal data. There was this difficult issue.

An object of the present invention is to detect the light intensity in the image output through the CCD in order to solve the problems of the prior art as described above and to measure the position value of the intersection point crossing the light intensity curve and the reference value according to the detected light intensity And the misalignment or misalignment between the pixels of the reproduced image and the pixels of the CCD array according to the result of the comparison of the measured position values and the set values of the reproduced images in the holographic digital data system. A mismatch measurement apparatus and method are provided.

In order to achieve the above object, the present invention provides a reproduction device of a system in which holographic digital data is recorded on a storage medium, wherein the data is recorded on the storage medium when the reference light of the same angle as that of the data recording on the storage medium is irradiated to the storage medium. Detects the light intensity of each CCD pixel in the CCD array taking an image and the signal output from the CCD array, and measures the position value of the point intersecting by crossing the reference value and the light intensity curve according to the detected light intensity. A signal processor that determines whether the pixel of the reproduced image and the pixel of the CCD array are aligned or miss-aligned according to the comparison result between the value and the set value, and decodes the data output when the signal processor determines the alignment. It includes a decoder to restore.

In order to achieve the above object, the method of the present invention is a reproducing method of a system in which holographic digital data is recorded on a storage medium, which irradiates the storage medium with a reference light having the same angle as that of the data recording on the storage medium, thereby recording the data recorded on the storage medium. Reproducing, photographing the image reproduced from the storage medium through a CCD array, detecting the light intensity of each CCD pixel signal captured by the CCD array, the light intensity curve according to the detected light intensity, and Measuring the position value of the point intersecting the predetermined reference value and crossing the predetermined reference value, comparing the measured position value with the set value, and comparing or misaligning the pixel between the pixel of the reproduced image and the pixel of the CCD array according to the comparison result. Determining whether it is aligned.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a block diagram showing a playback device of the holographic digital data system to which the present invention is applied. Referring to FIG. 3, the reproducing apparatus of the holographic digital data system to which the present invention is applied includes a storage medium 124, a CCD 128 array, a signal processor 140, a decoder 150, and the like. Fourier lenses 114 and 126 are provided at the front and rear of the storage medium 124.

The reproduction apparatus of the holographic digital data system to which the present invention is applied reproduces a page of binary data recorded in the form of an interference fringe on the storage medium 124 by irradiating only the reference light to the storage medium 124. The CCD 128 array converts the reproduced image data 130 into electrical data and transmits it to the signal processor 140. The signal processor 140 detects the light intensity of the CCD pixel photographing the image reproduced from the storage medium 124, and measures and measures the position value of the point intersecting by crossing the light intensity curve and the reference value according to the detected light intensity. It is determined whether the pixels of the reproduced image and the pixels of the CCD array are aligned or miss-aligned according to the comparison result of the set position value and the set value. If it is determined by the signal processing unit 140 that the reproduced image is aligned with the CCD pixel, one pixel of the reproduced image is oversampled to the m × m (m> 2) pixel size of the CCD and the original reproduction is performed from the corresponding oversampled pixel. After restoring the image pixels, ECC undergoes error correction. The decoder 150 decodes the data output from the signal processor 140, converts the original data into an original N × N size image (eg, 240 × 240), and outputs one page of binary data.

4 is a block diagram illustrating a mismatch detection apparatus of a reproduced image of the holographic digital data system according to the present invention. Referring to FIG. 4, the signal processor 140, which is a reproduction image mismatch detection device of the holographic digital data system of the present invention, is configured as follows.

An input unit 141 to which a user command is input, an array of CCD 128 for capturing an image reproduced from a storage medium, converting the image into electrical data, and outputting the light; and detecting light intensity of each pixel of the CCD 128 array. An intensity detector 143, a detection image buffer 145 for storing pixel data photographed by the CCD 128 array, and a light intensity curve by signals detected by the light intensity detector 143 intersect a preset reference value The misalignment measurer 147 for measuring the position value of the intersected point, and between the pixel of the reproduced image and the pixel of the CCD array when the position value measured by the misalignment measurer 147 has a set value. CPU 149 is determined to be aligned, otherwise it is determined to be misaligned. At this time, the CPU 149 controls the internal components of the signal processing unit 140, and furthermore, if it is determined that the misalignment measurement unit 147 is aligned, one of the images reproduced by the oversampling unit (not shown) is included. By oversampling the pixel to the m × m (m> 2) pixel size of the CCD, the original reconstructed image pixel is restored from the oversampled pixel, and the error correction unit (not shown) corrects the error of the restored data. Control the process to work. If it is determined that the misalignment measurement unit 147 is a misalignment, the CPU 149 outputs the misalignment information to an external display (not shown) and controls the oversampling unit and the error correction unit to not operate. .

5 is a flowchart illustrating a mismatch detection method of a reproduced image of the holographic digital data system according to the present invention. 3 to 5, a mismatch detection method of a reproduced image of a holographic digital data system according to the present invention is as follows.

First, the holographic digital data system of the present invention irradiates only the reference light to the storage medium 124 to reproduce one page of binary data recorded in the form of an interference fringe on the storage medium 124. In addition, the CPU 149 in the system controls to photograph the image reproduced from the storage medium 124 through the CCD 128 array, convert the image into electrical data, and output the electrical data. (S100) At this time, the image captured by the CCD 128 array is controlled. The image is stored in the detection image buffer 145.

The CPU 149 detects the light intensity of the signal output from the CCD 128 array through the light intensity detector 143 and transfers it to the misalignment measurer 147. (S102)

The CPU 149 intersects the light intensity curve according to the light intensity curve of the light intensity detector 143 with the preset reference value through the misalignment measurer 147 and measures the position value X 'of the intersected point. (S104 to S106) For example, as shown in FIG. 6A, when the pixel level of the reproduced image rises from Off to On, a portion where the level transition is continued to On is maintained. It becomes the border frame area. As shown in FIG. 6B, a portion of the pixel level photographed through the CCD 128 array and also rising from off to on is not accurately detected. Accordingly, the present invention converts the light intensity of the signal output from the CCD 128 array through the light intensity detector 143 into a curve to confirm whether the pixel is correctly matched between the reproduced image and the CCD array as shown in FIG. 6C. Then, the cross position value X ′ of the light intensity curve corresponding to the light intensity detected by the misalignment measuring unit 147 and the preset reference value W * On is measured. In this case, the preset reference value is a value that is halfway between the off level and the on level when the reproduced image and the pixels of the CCD 128 are correctly aligned.

The CPU 149 determines whether the position value X 'measured by the misalignment measurer 147 has a set value, and when the measured position value X' is the same as the set value, it is reproduced. It is determined that the image is aligned between the pixels of the CCD array and, otherwise, it is determined that there is a misalignment between the reproduced image and the pixels of the CCD array (S108 to S112).

Meanwhile, the misalignment measuring unit 147 of the present invention measures the position value X 'at the point where the light intensity curve corresponding to the detected light intensity intersects the predetermined reference value W * On as shown in FIG. 6D. For example, the light intensity intensities I (x) and I (x-1) of an arbitrary pixel pitch x and x-1 are obtained, and the curves of x and x-1 and a predetermined reference value (W * On) are obtained. The intersecting position value of X 'can be obtained.

 Pixel Pitch: X '= I (x)-I (x-1): W * On

Although not shown in the drawing, the CPU 149 controls whether the signal processor 140 continues to operate according to the misalignment of the misalignment measurer 147 or the misalignment result. That is, when the misalignment measurer 147 determines that the alignment is overaligned, the pixel of the image reproduced by the oversampling unit (not shown) is oversampled to the pixel size of m × m (m> 2) of the CCD. If the process is determined to be a misalignment, the misalignment information is output to an external display (not shown) and the oversampling is not operated.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

As described above, the present invention detects the light intensity in the image output through the CCD, measures the position value of the intersection point by crossing the light intensity curve and the reference value according to the detected light intensity, measured position value and the set value By accurately determining the alignment or misalignment between the pixels of the reproduced image and the pixels of the CCD array according to the comparison result, the reproduction efficiency of the holographic data can be greatly improved.

Claims (6)

A reproduction apparatus of a system in which holographic digital data is recorded on a storage medium, A CCD array for photographing a reproduction image of data recorded on the storage medium when the storage medium is irradiated with a reference light having the same angle as that of data recording on the storage medium; Detects the light intensity of each CCD pixel in the signal output from the CCD array, measures the position value of the point intersecting the light intensity curve according to the detected light intensity and the reference value, and compares the measured position value with the set value A signal processor that determines whether the pixels of the reproduced image and the pixels of the CCD array are aligned or miss-aligned according to A decoder which decodes the data output when the signal processor determines the alignment and restores the original data. Mimatch measurement device of the reproduced image in the holographic digital data system comprising a. The method of claim 1, The signal processor detects the light intensity of each CCD pixel of the CCD array, and a position of a point intersecting an arbitrary light intensity curve by the signals detected by the light intensity detector and a predetermined reference value. If the misalignment measuring unit that measures the value and the position value measured by the misalignment measuring unit have the set value, it is determined that the pixel between the pixel of the reproduced image and the pixel of the CCD array is aligned. And a mismatched measurement device of the reproduced image in the holographic digital data system further comprising a CPU which is determined to be aligned. The method of claim 2, The CPU may oversample one pixel of the reproduced image to a set pixel size of the CCD when the misalignment measurer determines that the alignment is aligned, and restore the original reproduced image pixel from the oversampled pixel, and the misalignment. Non-matching measurement device of a reproduced image in a holographic digital data system which controls mis-information while outputting miss-aligned information to an external display when it is determined in the measurement. The method of claim 1, And wherein the arbitrary light intensity curve is a curve in which the CCD pixel level rises from off to on. A reproduction method of a system in which holographic digital data is recorded on a storage medium, Irradiating the storage medium with a reference light at the same angle as the data recording of the storage medium to reproduce the data recorded on the storage medium; Photographing an image reproduced from the storage medium through a CCD array; Detecting light intensity of each CCD pixel signal photographed in the CCD array; Measuring a position value of a point where the light intensity curve intersects with the detected light intensity and a preset reference value and intersects the light intensity curve; Comparing the measured position value with a set value and determining whether the pixel of the reproduced image and the pixel of the CCD array are aligned or miss-aligned according to the comparison result Mimatch measurement method of the reproduced image in the holographic digital data system comprising a. The method of claim 5, After the determining of the alignment, the method further comprises oversampling one pixel of the reproduced image to the set pixel size of the CCD and restoring the original reproduced image pixel from the oversampled pixel. And after the step of determining, outputting the misaligned information to an external display while not oversampling the mismatched measurement method of the reproduced image in the holographic digital data system.

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