KR20080080749A - Method of calculating probability for optical information and method of decoding optical information, optical information processing apparatus using the same - Google Patents

Abstract

A method for calculating probability for optical information, a method for decoding optical information, and an optical information processing apparatus using the same are provided to perform decoding of optical information by using a balanced modulation code. An optical information processing apparatus comprises a light source(110), an optical information detector(160), a probability calculating part(170), and a data decoding part(200). The light source provides a reference light to an optical information storage medium. The optical information detector detects optical information reproduced in the optical information storage medium by the reference light. The probability calculating part calculates the probability for a code word of the optical information detected from the optical information detector. The data decoding part decodes the optical information of the code word by using the probability calculated in the probability calculating part.

Description

Method of calculating probability for optical information and method of decoding optical information, Optical information processing apparatus using the same}

1 is a block diagram showing an optical information processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a data encoding unit of FIG. 1.

3 is a block diagram illustrating a data decoding unit of FIG. 1.

4 is a block flowchart illustrating a method of calculating a probability value for decoding optical information according to an exemplary embodiment of the present invention.

FIG. 5 is an exemplary diagram illustrating an example of sorting pixels in FIG. 4 and dividing them into 'ON' pixels and 'OFF' pixels.

6 is a block flow diagram illustrating a decoding method of optical information according to an embodiment of the present invention.

** Explanation of symbols in main part of drawing **

100: optical information processing device

110: light source

120: optical separator

140: spatial light modulator

160: optical information detector

170: probability value calculation unit

180: data encoding unit

200: data decoding unit

The present invention relates to a method for calculating a probability value for decoding optical information, a method for decoding optical information, and an optical information processing apparatus using the same, and more particularly, to an LDPC decoder using a balanced modulation code. A method of calculating a probability value for decoding optical information providing a value, a decoding method of optical information, and an optical information processing apparatus using the same.

Optical information processing apparatuses for processing optical information include compact discs (CDs), digital versatile discs (DVDs), HD-DVDs, Blu-ray discs, near field optical processing apparatuses, and the like. In addition, there is an optical information processing apparatus using holography as a next-generation storage system having a larger capacity of storage.

Optical information processing apparatus using holography is a page-oriented memory in the principle of recording and reproducing image information. This can speed up the data rate. In addition, storage density may be improved through a multiplexing technique in which image information is overlaid and recorded in the same place on a storage medium.

An optical information processing apparatus using holography overlaps an information beam and reference beam including image information of original data with an optical recording medium, and then generates an interference pattern. In the optical information storage medium. In order to reproduce the recorded optical information, when the reference light is irradiated with the optical information storage medium, the reference light is diffracted by the interference pattern to generate regenerated light. If the recording reference light and the reproduction reference light are the same, reproduction light containing the same optical information as the optical information included in the information light at the time of recording is generated.

The image of the data page reproduced through the reproduction light is detected through a light receiving array element such as a complementary metal-oxide semiconductor (CMOS) or a charge coupled device (CCD). The detected data page is restored to the original data through a series of signal processing and decoding processes.

Meanwhile, the holographic optical information processing apparatus uses a modulation code and an error correction code in order to increase the storage density of the data page and the reliability of the data. As an error correcting code for the holographic optical information processing apparatus, such as a Reed-Solomon code has been proposed.

On the other hand, as a method of error correction, there is a low density parity check (LDPC) code which shows performance close to the theoretical channel capacity limit of Shannon.

The LDPC code is a linear block code in which most of the elements of the parity check matrix are '0'. A general parity check code consists of a block of information symbols and parity check symbols that are a modulo sum of specific information symbols to form a code word. The relationship between these check symbols and information symbols may be represented by a parity check matrix H. The parity check matrix H is represented by a set of linear homogeneous equations. In other words, the LDPC code is a type of parity check code, and is a coding method having a parity check matrix H having a large number of elements '0' and only a small number of randomly scattered weights.

The encoding process of the LDPC code having the parity check matrix H is as follows. Once the H matrix is obtained, a generator matrix G corresponding to the H matrix is obtained using the relationship of GH ^T = 0. The codeword C corresponding to the information symbol block X is obtained from C = XG. If the number of 1's per column and the number of 1's per row for the H matrix (M ㅧ N) are constant at W ㅧ (N / M), it is called a regular LDPC code. If the number of 1s in each column is not constant and the number of 1s in each row is not exactly W ㅧ (N / M), then it is called an irregular LDPC code.

Decoding of the LDPC code finds the most probabilistic codeword whose product with the parity check matrix H satisfies " 0 " from the received signal vector. Among the decoding methods of the LDPC code, the sum-product algorithm is a sum product algorithm for performing soft decision iterative decoding using probability values, or an LLR-BP using a log-likelihood ratio (LLR). (belief propagation) algorithm.

The LLR-BP algorithm is a process of obtaining a signal having a maximum probability of a codeword for a received signal. The LLR-BP algorithm obtains a codeword through row-oriented iteration decoding and column-wise iteration decoding from an initial LLR value.

In the holographic optical information processing apparatus using the LDPC code, the initial LLR value is set by obtaining the probability that the pixel is '0' and the probability that the pixel is '1' from the intensity of the data pixel. To this end, a specific mark is partially inserted between data pixels and used as information for obtaining a probability of the pixel.

However, the holographic optical information processing apparatus typically uses a laser having a light distribution of a Gaussian shape. Therefore, the data page to be reproduced may have an area in which many dark areas exist, and noise may occur in the data pixel. If there are many noisy or dark parts of a data pixel, it is impossible to obtain an accurate initial LLR value from the data pixel. Decoding failure occurs when the accuracy of the initial LLR value is outside the error correction range of the LDPC code. Therefore, there is a need for a method for obtaining an accurate initial LLR value.

The technical problem to be achieved by the present invention is a method of calculating a probability value for decoding optical information to obtain optical information decoding to obtain a more accurate initial probability value for LDPC code decoding using a balanced modulation code and The present invention provides a decoding method of optical information and an optical information processing apparatus using the same.

An optical information processing apparatus according to the present invention includes a light source for providing reference light to an optical information storage medium, an optical information detector for detecting optical information reproduced in the optical information storage medium by the reference light, and the light detected by the optical information detector. And a probability value calculator for calculating a probability value for a code word of information, and a data decoder for decoding optical information of the codeword using the probability value calculated by the probability value calculator.

The optical information stored in the optical information storage medium is modulated and recorded by a balanced modulation code that modulates n bits into m bits, and the codeword is an m-bit balanced codeword. A probability value calculator may calculate a probability value for the balanced codeword (n <m, n and m are natural numbers).

The data decoding unit repeatedly decodes the n-bit codeword demodulated by the balanced demodulator by using a balanced demodulator that demodulates the m-bit balanced codeword into an n-bit codeword and the probability value as an initial value. LDPC decoder to calculate a post-value.

The probability value calculating unit divides m pixels corresponding to the balanced codeword into 'ON' pixels and 'OFF' pixels, and calculates the probability values by an intensity difference between the 'ON' pixels and the 'OFF' pixels. can do.

The probability value calculator may calculate the probability value based on a difference between a minimum intensity of the 'ON' pixel and a maximum intensity of the 'OFF' pixel.

Meanwhile, a method of calculating a probability value for optical information decoding according to the present invention includes the steps of: arranging a plurality of pixels in intensity order, dividing the pixels into 'ON' pixels and 'OFF' pixels, and 'ON' pixels and the Calculating a probability value using an intensity difference of the 'OFF' pixel.

In the aligning, the plurality of pixels may be pixels corresponding to m-bit balanced codewords recorded by being modulated by a balanced modulation code that modulates n bits into m bits (n < m, n and m are natural numbers).

개의 픽셀을 'ON'픽셀로, 나머지 픽셀을 'OFF'픽셀로 구분하는 것일 수 있다. The step of dividing the pixel into an 'ON' pixel and an 'OFF' pixel may have a higher intensity among the pixels arranged in the intensity order.

Pixels may be divided into 'ON' pixels, and the remaining pixels may be divided into 'OFF' pixels.

번째 픽셀의 인텐시티

와

번째 픽셀의 인텐시티

를 적용하여, 'ON'픽셀에 대한 확률값은

로 산출하고, 'OFF'픽셀에 대한 확률값은

로 산출할 수 있다. If the intensity is arranged in descending order from the largest pixel in the step of sorting the pixels 'ON' and 'OFF',

The intensity of the first pixel

Wow

The intensity of the first pixel

By applying the probability value for the 'ON' pixel,

And the probability value for 'OFF' pixels is

It can be calculated as

이 설정된 크기보다 작은 경우, 상기 'ON'픽셀과 상기 'OFF' 픽셀의 경계가 불명확한 것으로 판단하여,

번째 픽셀의 인텐시티

및

번째 픽셀의 인텐시티

를 적용하여, 'ON'픽셀에 대한 확률값은

로 산출하고, 'OFF'픽셀에 대한 확률값은remind

If smaller than the set size, it is determined that the boundary between the 'ON' pixel and the 'OFF' pixel is unclear,

The intensity of the first pixel

And

The intensity of the first pixel

By applying the probability value for the 'ON' pixel,

And the probability value for 'OFF' pixels is

로 산출할 수 있다.

It can be calculated as

On the other hand, the optical information decoding method according to the present invention is a probability value for the balanced codeword from the m coded balanced codeword recorded by being modulated by a balanced modulation code that modulates n bits into m bits. Calculating (n <m, n and m are natural numbers), demodulating the balanced codeword into n-bit codewords, and using the probability value as an initial value, the n-bit codeword in a row direction and a column. A repeating decoding step of repeatedly decoding in a direction to obtain a post value of the n-bit codeword, and a provisional decoding step of determining whether to decode according to the post-value.

The calculating of the probability value may include arranging m pixels corresponding to the balanced codeword in intensity order, dividing the pixel into 'ON' pixels and 'OFF' pixels, and the 'ON' pixel and the ' Calculating an intensity difference of the OFF 'pixel.

개의 픽셀을 상기 'ON'픽셀로, 나머지 픽셀을 상기 'OFF'픽셀로 구분하여, 상기 'ON'픽셀의 최소 인텐시티와 상기 'OFF'픽셀의 최대 인텐시티의 차이를 상기 밸런스드 코드워드의 확률값으로 산출할 수 있다. The intensity is greater among the pixels arranged in the intensity order.

Dividing the number of pixels into the 'ON' pixel and the remaining pixels into the 'OFF' pixel, and calculating a difference between the minimum intensity of the 'ON' pixel and the maximum intensity of the 'OFF' pixel as a probability value of the balanced codeword. can do.

When the difference between the minimum intensity of the 'ON' pixel and the maximum intensity of the 'OFF' pixel is smaller than a set value, a pixel adjacent to the pixel having the least intensity among the 'ON' pixels in the pixels arranged in the intensity order The difference between the intensity of the pixel and the intensity of the pixel neighboring the pixel having the maximum intensity among the 'OFF' pixels may be added to the probability value.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the description of the embodiments of the present invention below.

1 is a block diagram showing an optical information processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a data encoding unit of FIG. 1. 3 is a block diagram illustrating a data decoding unit of FIG. 1.

As shown in FIG. 1, the optical information processing apparatus 100 according to the exemplary embodiment includes a light source 110, an optical information detector 160, a probability value calculating unit 170, and a data decoding unit 200. . Also, the optical information processing apparatus 100 may include a beam splitter 120, a spatial light modulator 140, a data encoder 180, a reflection mirror 133, 134, and a shutter 131, 132. ) Is further provided.

The optical information processing apparatus 100 according to the embodiment of the present invention may not employ the optical separator 120, the spatial light modulator 140, and the data encoding unit 180 when the reproduction information is exclusively used. In addition, the reproduction method may be implemented in various ways, and at the same time, the optical information may be recorded or reproduced by various multiplexing methods. That is, the configuration of the optical system for processing the optical information may be variously modified.

Hereinafter, the operation of the optical information processing apparatus 100 according to the embodiment of the present invention will be described.

The light irradiated from the light source 110 for recording the optical information is separated into the reference light R and the information light I through the light separator 120. The reference light R passes through the shutter 131 and is reflected by the anti-smirror 133 to be incident on the optical information storage medium 150 at a predetermined angle.

The information light I passes through the shutter 132 and enters the spatial light modulator 140 after the path is changed by the reflection mirror 134. At this time, the spatial light modulator 140 receives binary data, that is, data page information, in units of encoded pages provided from the data encoding unit 180.

As shown in FIG. 2, the data encoder 180 includes an LDPC encoder 181 and a balanced modulator 182. The LDPC encoder 181 converts data input data provided in units of bits into LDPC codes. The balanced modulator 182 modulates the LDPC code into a balanced code word. At this time, the balanced modulator 182 modulates the n-bit LDPC code into a m-bit balanced codeword using a balanced modulation code (n <m, n and m are natural numbers).

The spatial light modulator 140 optically modulates the data page information input from the data encoding unit 180 to generate a two-dimensional imaged data page, and projects it onto the incident information light I to provide an optical information storage medium ( 150).

When the reference light R and the information light I are incident on the optical information storage medium 150, the reference light R and the information light I are generated by the interference between the incident reference light R and the information light I in the optical information storage medium 150. According to the intensity of the interference pattern, a light induced generation of mobile charge occurs, and the interference pattern is recorded.

The reflection mirror 133 may adjust the angle at which the reference light R is incident on the optical information storage medium 150 to implement angle multiplexing. For this purpose, the reflective mirror 133 may be a rotating mirror such as a galvano mirror. In addition, the multiplexing method may be used in addition to the angular multiplexing. For example, there are methods such as shift multiplexing, phase code multiplexing, or angle-shift multiplexing, and for this, the configuration of the optical system may be partially modified.

Meanwhile, in order to reproduce the recorded data, only the reference light R may be irradiated to the optical information storage medium 150. In reproduction, the shutter 132 on the path of the information light I blocks the information light I separated by the light separator 120.

In this case, the reference light R reflected by the reflection mirror 133 is diffracted by an interference pattern recorded on the optical information storage medium 150 to generate reproduction light having an image of a data page. The reproduced light is detected by the optical information detector 160 as an image of the data page. The reproduced light is detected by the optical information detector 160 as an image of the data page. The image of the detected data page calculates a probability function for the balanced codeword through the probability value calculator 170, and is then decoded by the data decoder 200. At this time, the optical information detector 160 is composed of a light receiving array element such as CMOS or CCD.

The data decoding unit 200 is a device for decoding the data page image into binary data. As shown in FIG. 3, the data decoding unit 200 includes a balanced demodulator 201 and an LDPC decoder 202. The balanced demodulator 201 demodulates the m-bit balanced code word into n-bit LDPC codes. The LDPC decoder 202 decodes the LDPC code by using the probability value provided from the probability value calculator 170 and outputs final output data.

Hereinafter, a method of calculating a probability value for decoding optical information and a decoding method using the same will be described in more detail.

4 is a block flowchart illustrating a method of calculating a probability value for decoding optical information according to an exemplary embodiment of the present invention. FIG. 5 is an exemplary diagram illustrating an example of sorting pixels in FIG. 4 and dividing them into 'ON' pixels and 'OFF' pixels.

When decoding data using an LDPC code, a probability value is typically used to initialize a variable node. In an embodiment of the present invention, a probability value for a balanced codeword of m bits recorded by being modulated by a balanced modulation code that modulates n bits into m bits is used as an initial value for the LDPC code.

The probability value calculator 170 classifies the pixels in a balanced codeword unit in the data page detected by the optical information detector 160. The pixel corresponding to the m bit balanced codeword consists of m 'ON' and 'OFF' pixels. The probability value calculator 170 sorts the pixels corresponding to the balanced codewords in the order of intensity (S10). In this case, as shown in FIG. 5, the pixels having the greatest intensity may be arranged in descending order.

개의 픽셀이 'ON'픽셀로, 나머지 픽셀이 'OFF'픽셀로 구분될 수 있다. Subsequently, the probability value calculator 170 divides the pixel into 'ON' pixels and 'OFF' pixels (S20). Balanced modulation code modulates the number of 'ON' and 'OFF' to be the same.

Pixels may be divided into 'ON' pixels, and the remaining pixels may be divided into 'OFF' pixels.

번째 픽셀이 'ON'픽셀 중 인텐시티가 최소인 픽셀이고,

번째 픽셀이 'OFF'픽셀 중 인텐시티가 최대인 픽셀이 되어, 상기 두 픽셀이 'ON'픽셀과 'OFF'픽셀의 경계가 될 수 있다. If the intensity is sorted in descending order from the largest pixel,

Pixel is the least intense pixel among "ON" pixels,

The second pixel may be a pixel having the highest intensity among the 'OFF' pixels, and the two pixels may be the boundary between the 'ON' pixel and the 'OFF' pixel.

번째 픽셀의 인텐시티

와

번째 픽셀의 인텐시티

를 적용한다. 'ON'픽셀에 대한 확률값은 수학식 1로 구하고, 'OFF'픽셀에 대한 확률값은 수학식 2로 구한다. The probability values for the 'ON' pixels and the 'OFF' pixels may be represented by calculating an intensity difference between the 'ON' pixels and the 'OFF' pixels (S30). At this time, the boundary between the 'ON' pixel and the 'OFF' pixel

The intensity of the first pixel

Wow

The intensity of the first pixel

Apply. The probability value for the 'ON' pixel is obtained by Equation 1, and the probability value for the 'OFF' pixel is obtained by Equation 2.

On the other hand, the boundary between the 'ON' pixel and the 'OFF' pixel may appear unclear. That is, the intensity difference between the 'ON' pixel and the 'OFF' pixel may appear small due to noise generated during storage and reproduction of the optical information. When the LDPC code is decoded using the probability value in this case, error correction performance may be deteriorated and decoding failure may be generated.

을 사전에 설정된 크기와 비교한다.

이 설정된 크기보다 큰 경우에는 'ON'픽셀과 'OFF' 픽셀의 경계가 명확한 것으로 판단하고, 설정된 크기보다 작은 경우 'ON'픽셀과 'OFF' 픽셀의 경계가 불명확한 것으로 판단한다. Therefore, it is determined whether the boundary between the 'ON' pixel and the 'OFF' pixel is clear (S40). That is, the intensity difference between 'ON' and 'OFF' pixels

Is compared with the preset size.

If the size is larger than the set size, the boundary between the 'ON' pixel and the 'OFF' pixel is determined to be clear.

이 설정된 크기보다 작은 경우,

번째 픽셀의 인텐시티

및

번째 픽셀의 인텐시티

를 추가 적용한다(S50). 이때, 'ON'픽셀에 대한 확률값은 수학식 3으로 구하고, 'OFF'픽셀에 대한 확률값은 수학식 4로 구한다. As a result of the determination,

Is less than the set size,

The intensity of the first pixel

And

The intensity of the first pixel

Apply additionally (S50). At this time, the probability value for the 'ON' pixel is obtained by Equation 3, and the probability value for the 'OFF' pixel is obtained by Equation 4.

The probability values for the 'ON' pixels and the 'OFF' pixels obtained as described above are provided as initial values for decoding the LDPC code (S60).

On the other hand, m-bit balanced codewords are demodulated by n-bit codewords by the balanced demodulator 201 and provided to the LDPC decoder 202.

The probability values for the 'ON' pixels and the 'OFF' pixels have been calculated as difference in intensity of pixels corresponding to the boundary between the 'ON' pixels and the 'OFF' pixels, but the present invention is not limited thereto. Similar calculation methods can be applied depending on the nature of the signal being generated. For example, when the intensities of the 'OFF' pixels are detected with similar values, the difference between the minimum intensity of the 'ON' pixel and the minimum intensity of the 'OFF' pixel is calculated to be a probability value for the 'ON' pixel and the 'OFF' pixel. Can be used as In addition, when the boundary between the 'ON' pixel and the 'OFF' pixel is unclear, an additional pixel may be selected and applied differently.

Hereinafter, a method of decoding optical information by applying a probability value for a balanced codeword as an initial value for decoding an LDPC code will be described.

6 is a block flow diagram illustrating a decoding method of optical information according to an embodiment of the present invention.

이다. 여기서 코드워드

는 송신 신호

로 매핑된다. If the codeword is c , the transmitted signal is x , the received signal is y , and the channel noise is n ,

to be. Codeword

Transmit signal

Is mapped to.

의 값이 최대가 되는 코드워드

를 구하는 것이다. Decoding is a process of obtaining a signal in which a probability of a codeword with respect to a received signal is maximized. In other words

The codeword whose maximum is.

To obtain.

로 나타낸다. m번째 체크에 참여하는 비트들의 집합을

으로 표시한다. n번째 비트에 참여하는 체크들의 집합을

으로 표시한다. 집합 N(m)과 M(n)의 크기는 각각 |N(m)| 와 |M(n)|로 나타낸다.

은 n번째 비트를 제외한 N(m)을 말한다.

은 m번째 체크를 제외한 M(m)을 말한다. The size of parity check matrix H is M x N,

Represented by set of bits that participate in the mth check

Indicated by. set of checks that participate in the nth bit

Indicated by. The sizes of sets N (m) and M (n) are | N (m) | And | M (n) |.

Is N (m) except nth bit.

Is M (m) except the mth check.

The symbols used in the iterative decoding algorithm are as follows.

은 수신된 신호 y로부터 얻은 n번째 비트의 LLR이다.

Is the LLR of the nth bit obtained from the received signal y.

은 m 번째 체크노드에서 n번째 비트노드로 가는 n번째 비트의 LLR이다.

Is the LLR of the nth bit from the mth checknode to the nth bitnode.

은 n번째 비트노드에서 m번째 체크노드로 가는 n번째 비트의 LLR이다.

Is the LLR of the nth bit from the nth bitnode to the mth checknode.

은 각각의 반복에서 계산된 n번째 비트의 사후(a posteriori) LLR이다.

Is a posteriori LLR of the nth bit calculated at each iteration.

에 해당)은 수학식 1, 수학식 2 또는 수학식 3, 수학식 4에서 구한 확률값이 적용되고, 각각의 m, n에 대하여

으로 초기화된다(S110). First, in the initialization step, the LLR of the codeword (corresponding to the received signal y) demodulated by the balanced demodulator 201 (the

Equation 1), Equation 1, Equation 2 or Equation 3, the probability value obtained from Equation 4 is applied, for each m, n

Initialized to (S110).

After the initialization is completed, the after-value is calculated by repeatedly decoding in the row and column directions. The row-wise iterative decoding step for this is defined as in Equation 5 for each m, n (S120).

Following the row-wise iterative decoding step, the column-wise iterative decoding step is updated for each m and n as shown in Equation 6 (S130).

을 결정한다(S140).And the provisional decoding step of determining whether to decode according to the post-value obtained thereby, as shown in equation (7)

Determine (S140).

의 값에 따라 반복 여부를 결정한다(S150). to the next,

It is determined whether to repeat according to the value of (S150).

이면, 복호 과정을 중지하고

를 올바른 복호 결과로 판정한다(S155). if

If so, stop the decryption process

Is determined to be a correct decoding result (S155).

이면, 최대 반복 횟수만큼 복호를 반복 수행했는지 여부를 판단한다(S160). 최대 반복 횟수만큼 복호를 수행하였으면, 복호를 중지하고 복호 실패를 선언한다(S165). if

In this case, it is determined whether decoding has been repeatedly performed as many times as the maximum number of repetitions (S160). If decoding has been performed as many times as the maximum number of repetitions, decoding is stopped and a decoding failure is declared (S165).

The data page of the holographic optical information processing apparatus may be composed of a plurality of code words, and the entire data page can be decoded by decoding each code word by the above-described method.

On the other hand, the above-described decoding method has been described as an embodiment to decode the data using the LLR-BP algorithm. However, other algorithms for decoding LDPC codes use probability values in most LDPC decoding algorithms, such as the uniformly most powerful belief-propagation (UMP-BP) algorithm, a posteriori probability (APP) algorithm, or sum-product algorithm. The method may also be applied to the calculation.

As described above, a method for calculating a probability value for decoding optical information, a method for decoding optical information, and an optical information processing apparatus using the same, calculate an initial probability value for decoding an LDPC code by using a balanced modulation code. It is possible to improve the optical information decoding efficiency in the optical information processing apparatus by performing the decoding of the optical information by obtaining a more accurate value.

Claims (14)

A light source providing reference light to an optical information storage medium; An optical information detector for detecting optical information reproduced from the optical information storage medium by the reference light; A probability value calculator configured to calculate a probability value for a code word of the optical information detected by the optical information detector; And And a data decoder which decodes the optical information of the codeword by using the probability value calculated by the probability value calculating unit. The optical information stored in the optical information storage medium is modulated and recorded by a balanced modulation code for modulating n bits into m bits. And a probability code calculator, wherein the probability value calculator calculates a probability value for the balanced codeword (n <m, n and m are natural numbers). 3. The apparatus of claim 2, wherein the data decoding unit comprises: a balanced demodulator for demodulating the m-bit balanced codeword into an n-bit codeword; And And an LDPC decoder using the probability value as an initial value and repeatedly decoding the n-bit codeword demodulated by the balanced demodulator to calculate a post-value. The intensity value of the 'ON' pixel and the 'OFF' pixel by dividing m pixels corresponding to the balanced codeword into 'ON' pixels and 'OFF' pixels. And calculating the probability value by the difference. The optical information processing apparatus of claim 4, wherein the probability value calculator calculates the probability value by a difference between a minimum intensity of the 'ON' pixel and a maximum intensity of the 'OFF' pixel. Sorting the plurality of pixels in intensity order; Dividing the pixel into 'ON' pixels and 'OFF' pixels; And And calculating a probability value by using an intensity difference between the 'ON' pixel and the 'OFF' pixel. The pixel of claim 6, wherein, in the aligning, the plurality of pixels corresponds to m-bit balanced codewords recorded by being modulated by a balanced modulation code that modulates n bits into m bits. Probability value calculation method for decoding optical information, characterized in that (n <m, n and m is a natural number). The method of claim 7, wherein the dividing into the 'ON' pixels and the 'OFF' pixels is characterized in that the intensity is high among the pixels arranged in the intensity order.

And a plurality of pixels are divided into 'ON' pixels, and the remaining pixels are divided into 'OFF' pixels. The method of claim 8, wherein when the intensity is arranged in descending order from the largest pixel in the step of sorting the pixels 'ON' and 'OFF',

The intensity of the first pixel

Wow

The intensity of the first pixel

By applying the probability value for the 'ON' pixel,

To calculate, The probability value for the "OFF" pixel is

Probability value calculation method for optical information decoding, characterized in that for calculating. The method of claim 9, wherein

If smaller than the set size, it is determined that the boundary between the 'ON' pixel and the 'OFF' pixel is unclear,

The intensity of the first pixel

And

The intensity of the first pixel

By applying the probability value for the 'ON' pixel,

To calculate, The probability value for the "OFF" pixel is

Probability value calculation method for optical information decoding, characterized in that for calculating. calculating a probability value for the balanced codeword from m-bit balanced codewords modulated by a balanced modulation code that modulates n bits into m bits (n <m, n and m) Is a natural number); Demodulating the balanced codeword into an n-bit codeword; An iterative decoding step of repeatedly decoding the n-bit codeword in a row direction and a column direction using the probability value as an initial value to obtain a posterior value of the n-bit codeword; And And a provisional decoding step of determining whether to decode according to the post value. 12. The method of claim 11, wherein the calculating of the probability value comprises: sorting m pixels corresponding to the balanced codeword in intensity order, dividing the pixel into an 'ON' pixel and an 'OFF' pixel, and And calculating an intensity difference between the ON pixel and the OFF pixel. The method of claim 12, wherein the intensity of the pixels arranged in the intensity order is large.

Dividing the number of pixels into the 'ON' pixel and the remaining pixels into the 'OFF' pixel, and calculating a difference between the minimum intensity of the 'ON' pixel and the maximum intensity of the 'OFF' pixel as a probability value of the balanced codeword. Optical information decoding method, characterized in that. 15. The method of claim 13, wherein when the difference between the minimum intensity of the 'ON' pixel and the maximum intensity of the 'OFF' pixel is smaller than a set value, the minimum intensity of the 'ON' pixels in the pixels arranged in the intensity order is determined. And a difference between an intensity of a pixel neighboring a pixel having a pixel and an intensity of a pixel neighboring a pixel having a maximum intensity among the 'OFF' pixels, is added to the probability value.

Images