KR101084093B1 - Method for detecting rotation of image in hdds system - Google Patents

Abstract

The present invention relates to a method for detecting rotation of an image in a HDDS system. The present invention relates to a rotation degree in the initial data reading direction of a CCD array in order to detect a rotation state of an image when reading an image of page data recorded in a holographic digital data storage device. By adding the rotation detection pattern that can know the direction and direction, even if the data is not read from the CCD array, the state of the rotation detection pattern is identified from the initial data J to identify the rotation state, and oversampled and decoded according to the identified rotation state. Along with this, there is also the advantage of reducing the memory stored temporarily to find the four corners of the image.

HDDS, hologram, image, rotation, capture, capture, oversampling

Description

METHODS FOR DETECTING ROTATION OF IMAGE IN HDDS SYSTEM

1 is a block diagram showing a general HDDS system.

FIG. 2 is a view showing 6 * 6 pixel image data reproduced in an 8 * 8 array of CCDs in a general HDDS system, where (A) is a state where rotation has not occurred and (B) is a view where rotation has occurred.

3 is a diagram of the HDDS system according to the present invention. It is a flowchart for explaining a rotation detection method.

4 is a diagram illustrating a page data image in which a rotation sensing pattern is inserted by an image rotation detection method in a HDDS system according to the present invention.

5 is a view showing a rotation detection pattern according to the present invention.

6 is a view showing a CCD array for explaining the decoding process according to the rotation state identified by the present invention.

   -Explanation of symbols for the main parts of the drawings-

10 light source 12 light separator

14, 18: shutter 16, 20: reflector

22: spatial light modulator 24: storage medium

26: CCD 28: coding unit

30: decoding unit 100: page data image

102: reference frame 104: data area

106: rotation detection pattern

The present invention relates to a method of detecting rotation of an image in a HDDS system, and more particularly, to read initial data of a CCD array in order to detect a rotation state of an image when reading an image of page data recorded in a holographic digital data storage device. Rotation detection method that knows the rotation degree and direction in the direction to detect the rotation of the image in HDDS system that can over-sample and decode after detecting the rotation state through the initial data even without reading all the data from the CCD array It is about.

As the information industry develops, a large capacity of a device for storing information and a high speed of processing are required. As a result, the holographic ROM, which is widely known as a device for recording and reproducing holographic digital data, can store a large amount of information in one bit of an optical disc such as a CD or a DVD. Speed is fast Because of these advantages, holographic digital data storage is in the spotlight as the next generation of mass information storage.

Holographic Digital Data Storage (HDDS) has attracted much attention as the next generation of data storage for broadcast and video editing because it can record one million bits of data in three dimensions and in parallel. In order to do this, Inphase used a data storage method called Pages and Books. The holographic recording method records data through a single exposure to the laser on a page-by-page basis, and records not only the intensity of the laser but also the wave, which significantly increases the recording capacity per unit area compared to the optical storage that is recorded on the existing cross section.

In addition, I / O uses parallel to outperform all existing optical data storage formats in speed.

1 is a block diagram showing a general HDDS system.

As shown here, first, in the optical separator 12, the laser light incident from the light source 10 is split into the reference light and the signal light, where the reference light of the vertically polarized light is provided to the reference light processing path S1 and branched. The received signal light is provided to the signal light processing path S2. In addition, the shutter 14 and the reflector 16 are provided in the emission direction of the reference light on the reference light processing path S1. Through the light transmission path, the reference light processing path S1 receives the reference light required for recording or reproducing hologram data. It is reflected to the predetermined predetermined deflection angle and provided to the storage medium 24.

Accordingly, the vertically polarized reference light branched from the light separator 12 and incident through the opening of the shutter 14 is adjusted to an extent sufficient to be adjusted through an optical lens (not shown) or the like and cover the size of the signal light. Through the reflector 16 driven by the actuator 30, the reference light is deflected at a predetermined angle, for example, a recording angle during recording or a preset reproduction angle for reproduction, and then incident on the storage medium 24.

Here, the reference light used at the time of recording or reproduction is controlled by rotating the reflector 16 whenever the binary data of each page unit is recorded on the storage medium 24 to change the deflection angle ??. Through this reference light deflection technique, hundreds to thousands of hologram data may be stored in the storage medium 24 or the stored hologram data may be reproduced.

On the other hand, the shutter 18, the reflector 20, and the spatial light modulator 22 are sequentially provided on the signal light processing path S2 in the direction in which the signal light is emitted. The shutter 18 remains open in the recording mode. In play mode, it is blocked. The signal light branched from the optical separator 12 and incident through the opening of the shutter 18 is reflected at a predetermined deflection angle through the reflector 20 and then transmitted to the spatial light modulator 22.

Subsequently, in the spatial light modulator 22, the signal light transmitted from the reflector 20 is modulated in units of one page of binary data of light and shade of pixels according to input data provided from the data coding unit 28. For example, when the input data is image data in one frame unit of the image, the signal light incident on the spatial light modulator 22 is modulated into signal light in one frame unit, and then inputted from the reflector 16 of the reference light processing path S1. The light is incident on the storage medium 24 in synchronization with the reference light. Accordingly, in the storage medium 24, the signal light modulated in units of pages of binary data provided from the spatial light modulator 22 in the recording mode is incident from the reflector 16 with the deflection angle ?? corresponding thereto. An interference fringe obtained through interference between recording reference lights is recorded. That is, the light induced phenomenon of the kinetic charge is generated inside the storage medium 24 according to the intensity of the interference fringes obtained by the interference between the modulated signal light and the reference light. An interference fringe of the hologram data is recorded.

Subsequently, when the hologram data recorded on the storage medium 24 is reproduced, the shutter 18 on the signal light processing path S2 is cut off and the shutter 14 on the reference light processing path S1 is open. . Then, the reference light (reproducing reference light) branched from the optical separator 12 is reflected through the reflector 16 and irradiated to the storage medium 24. As a result, in the storage medium 24, the interference fringe recorded by the reference light for reproduction. Is diffracted by the incident reference light for reproduction, and demodulated into one page of binary data composed of original pixel contrast, and the demodulated reproduction signal is irradiated to the CCD 26. Accordingly, the CCD 26 restores the reproduction output irradiated from the storage medium 24 to the original data, that is, the electric signal, and the reproduction signal restored here is reproduced and output through the data decoding unit 30.

In the HDDS system, since data is a page-based pattern rather than a bit-based pattern, in order to accurately determine the data, the HDDS system needs to know the position where the data of the page starts and of course, does not rotate.

However, in a practical system, since the pagepater on the CCD 26 can be rotated and detected, even if the frame is found even when the image is rotated, the data cannot be effectively restored.

Therefore, the coordinates of four corners (upper left, lower left, upper right and lower) of one frame of the reproduced page data are obtained, and then the degree of rotation of the frame is determined by the difference of their relative values, and the corresponding oversampling technique is applied.

For example, the figure shown in Fig. 2 shows 6 * 6 pixel image data reproduced in an 8 * 8 array of CCDs, where (A) is a state where no rotation has occurred and (B) is a state where rotation has occurred. The figure shown.

As shown here, the four corner coordinates of (A) where rotation does not occur are (1,1), (1,6), (6,1), (6,6), but four of (B) where rotation occurs. The corner coordinates are (1,1), (2,6), (6,0), and (7,5), which can be determined to be rotated about one pixel in the counterclockwise direction. Therefore, when detecting data by one rotated pixel, the position is changed to perform decoding.

However, this method of detecting the rotation of the frame is possible only by finding four modalities of the reproduced image. However, in order to find the four corners, the CCD 26 receives all the data sequentially outputted one pixel at a time and can grasp the rotation state, and all the data received to oversample the data according to the degree of rotation. Should be saved.

Therefore, there is a problem in that time consuming to wait until all the data of the CCD 26 is read to find the degree of rotation, and there is a problem that a lot of memory (RAM) for storing all data.

SUMMARY OF THE INVENTION The present invention was created to solve the above problems, and an object of the present invention is to provide initial data of a CCD array to detect a rotation state of an image when reading an image of page data recorded in a holographic digital data storage device. Rotation detection pattern that knows the rotation degree and direction in the reading direction adds rotation detection through the initial data to detect the rotation state through the initial data even if the CCD array does not read all the data. In providing a method.

The present invention for realizing the above object is a first step of capturing an image of the holographic page data in the HDDS system, a second step of detecting the frame initial point in the image of the page data captured in the first step, A third step of reading the center line of the rotation sensing pattern based on the initial point detected in the second step; a fourth step of determining whether the values read in the third step are the same as the center line pattern of the rotation sensing pattern; If the result of the judgment in step 4 is not the same as the center line pattern, the center line of the rotation detection pattern is read and moved at the same point, and the current point is stored as the rotation point and returned to step 4 to repeat to the end of the line. In step 5 and step 5, if the data is repeated to the end of the line, the data area is divided based on the number of movements And a sixth step of oversampling and decoding.

In the present invention, the rotation detection pattern is formed in the initial reading position along the reading direction of the page data in the CCD array of the HDDS system.

In the present invention, the rotation detection pattern is characterized in that it further comprises a left line and a right line having a pattern opposite to each other on the left and right with respect to the center line.

In the present invention, the center line of the rotation detection pattern is formed so that the on-pattern and the off-pattern one by one, the left line and the right line is characterized in that the predetermined number of on-pattern and the predetermined number of off-pattern are formed to alternate with each other. do.

At this time, the predetermined number is characterized in that 4 pixels.

According to the present invention, when the page data is read in the HDDS system, data of the rotation detection pattern formed at the initial reading position along the leading direction of the page data in the CCD array is analyzed and there is no rotation when the pattern of the center line is read. However, if the pattern of the left line and the right line is read, it is determined that the rotation is made in the corresponding direction, and the process of storing the rotation direction and the rotation point until the end of the line is repeated. When the data is read based on the oversampling to decode.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present embodiment is not intended to limit the scope of the present invention, but is presented by way of example only and the same parts as in the conventional configuration using the same reference numerals and names.

3 is a flowchart illustrating an image rotation detection method in a HDDS system according to the present invention.

First, in the HDDS system, the image of the holographic page data as shown in FIG. 4 is captured through the CCD 26 (S10).

Then, the initial point of frame 102 in the image 100 of the captured page data is the initial point through relative comparison of line sum or line sum with adjacent line as in the conventional method. It is detected (S12).

When the initial point is detected as described above, the center line of the rotation detection pattern 106 is read based on the initial point (S14).

The rotation detection pattern 106 is formed at an initial reading position along the reading direction of the page data so that the rotation detection pattern 106 can be read first when reading from the CCD 26. At this time, the data area 104 is encoded by a conventional method and a rotation sensing pattern 106 is inserted in addition to this page data.

Thus, if the size of a conventional page data image 100 is 486 * 486 (including frames), then the image size encoded by the present invention is 490 * 486 including the rotational sense pattern 106 and the excess of adjacent lines. This results in different image sizes.

As shown in FIG. 5, the rotation sensing pattern 106 applied in the present embodiment is formed of three lines, and a left line and a right line having opposite patterns on the left and right sides of the center line are formed.

The center line is formed of “10101010” so that the on pattern and the off pattern alternate with each other by 1 bit, and the left line and the right line are formed such that a predetermined number of on patterns and a predetermined number of off patterns alternate with each other. That is, the left line is formed of "11110000" and the right line is formed of "00001111" so as to be opposite to the left line.

Therefore, when reading the data of the center line "10101010", if data of "11110000" is read, it can be determined that 1 bit rotation has occurred in the counterclockwise direction, and if the data of "00001111" is read, 1 bit in the clockwise direction It can be determined that the rotation has occurred.

According to this principle, when the center line of the rotation detection pattern is read based on the initial point of the frame, it is determined whether the center line pattern "10101010" is read until the end of the line (S16) (S18).

At this time, if the center line pattern "10101010" is repeated to the end of the line, it is determined that the currently captured image has no rotation. If a slight rotation occurs, it may be determined that the rotation is not sufficient to affect decoding.

Therefore, when oversampling is applied to the data region 104, the data is read and decoded by applying a state in which no rotation occurs (S22).

However, if the center line is read but the center line pattern "10101010" is repeated and "11110000" appears, it can be determined that the current image is rotated counterclockwise as a whole, and "00001111" is repeated after "10101010". If it does, it can be determined that the current image is rotated clockwise as a whole. That is, it may be assumed that the image is rotated around the initial point of the image.

At this time, since the left line and the right line are formed at intervals of 1 pixel in the center line, it can be determined that the 1 pixel rotation effect has occurred. Therefore, the current point is stored as a rotation point to be applied when oversampling (S18).

To find the point where the rotation affects decoding, the centerline is moved 1 pixel in the direction of rotation from the current point, and the data is read from the centerline to the end of the line. After that, "10101010" is repeated in the same way as above, "11110000" comes out or "00001111" comes out of the point.

If "10101010" is repeated to the end of the line, it may be determined that the section affected by the rotation is from the first rotation point to the end of the line. However, if there is a section in which "10101010" is repeated and then "11110000" or "00001111" appears, the subsequent section will have a 1 pixel rotation effect more than the first rotation point, and a 2 pixel effect compared to the initial point. It is considered to have occurred.

If there is another section in which data is overturned, the above process is repeated. However, in general, since the degree of rotation of the image formed on the CCD 26 is not so great, the point where the data is overturned will be one to two points.

By repeating the above process to the end of the line of the rotation detection pattern, the data area is oversampled and decoded based on the number of movements of the center line, the direction of movement, and the rotation point (S22) (S24).

The process of oversampling and decoding according to the rotation state identified through the above process will be described with reference to FIG. 6 as follows.

If it is determined that there is no rotation by the above method, assuming that the image is formed on the CCD 26 pixel as shown here, the data is sequentially decoded from 1 to 25.

By the way, if the rotation point has the rotational effect by the above method and the position of the "11110000" data detected is the position of "3" of the CCD, the position of "11" is also the starting point affected by the rotation. Therefore, by rotating one pixel counterclockwise based on the position of "1", the effect of "3" downward in the vertical direction will be shifted to the right, and the effect of "11" right in the horizontal direction to the upward. There will be.

Therefore, when reading data, 1, 2, 8, 9, 10, 6, 7, 13, 14, 15, C, 11, 17, 18, 19, D, 16, The decoding is performed in the order of 22, 23, 24, E, 21, H, I, and J. If the rotation effect is spread over two pixels, it is moved again with respect to the second appeared point and decoded.

As described above, the present invention provides a rotation sensing unit capable of knowing the degree of rotation and direction in the initial data reading direction of the CCD array to detect the rotation state of the image when reading the image of the page data recorded in the holographic digital data storage device. By adding a pattern, even if you do not read all the data from the CCD array, you can identify the rotation state by identifying the state of the rotation detection pattern in the initial data J, and oversample and decode the four corners of the image with the temporal benefit. There is also an advantage to reduce the memory that was temporarily stored to find.

Claims (5)

A first step of capturing an image of holographic page data in the HDDS system, A second step of detecting a frame initial point in the image of the page data captured in the first step; A third step of reading the center line of the rotation detection pattern based on the initial point detected in the second step; A fourth step of determining whether the values read in the third step are the same as the center line pattern of the rotation detection pattern; If the result of the determination in the fourth step is not the same as the center line pattern, the center line of the rotation sensing pattern is read and moved at a different point, and the current point is stored as the rotation point and returned to the fourth step. Repeat the fifth step to the end, A sixth step of oversampling and decoding the data area based on the number of movements of the center line, the moving direction and the rotation point in the case of repeating to the end of the line in the fifth step; Image rotation detection method in the HDDS system, characterized in that consisting of. The method of claim 1, wherein the rotation detection pattern is formed at an initial reading position along a reading direction of page data in a CCD array of the HDDS system. The method of claim 1, wherein the rotation detection pattern further comprises a left line and a right line having opposite patterns on the left and right sides of the center line. According to claim 1, wherein the center line of the rotation detection pattern is formed so that the on pattern and the off pattern one by one, and the left line and the right line are formed so that a predetermined number of on-pattern and a predetermined number of off-pattern alternate with each other. Image rotation detection method in the HDDS system, characterized in that. The method of claim 4, wherein the predetermined number is 4 pixels.

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