JPH0799579A - Picture processing device - Google Patents

Abstract

PURPOSE:To attain sure decoding processing by terminating decoding processing for one page on the condition of recognition of an end in the main scanning direction and recognition of an EOI marker or a DNL marker so as to prevent the decoding processing of one page from being finished before the decoding processing of all blocks is finished. CONSTITUTION:A Huffman coding part 120 decodes coded data stored in a code memory 101 and coded by the JPEG base line coding system in the unit of picture data for one color for one block of 8X8 size through processing means of quantization processing, zigzag scanning and Huffman coding. A main scanning direction counter 103 counts the number of picture elements in the main scanning direction and outputs a carry signal when the processing is advanced up to the end in the main scanning direction. A subscanning direction counter 107 provides an output of a carry signal when data are decoded by the number of lines in the subscanning direction designated by an SOF marker. A decoding part 120 terminates decoding processing for one page by recognizing the output of the carry signal from the counters 103, 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus,
The present invention relates to an image processing apparatus that decodes coded data coded by the PEG baseline coding method.

[0002]

2. Description of the Related Art FIG. 27 is a diagram showing an example of a conventional color image decoding apparatus of this type, and a conventional image operation will be described in detail with reference to FIG. In FIG. 27, 101 is J
ADC of PEG (Joint Photographic Experts Group)
A code memory for storing code data encoded by a T (Adaptre Discrete Cosine Transform) baseline method (hereinafter referred to as “JPEG baseline encoding method”),
Reference numeral 102 is a Huffman decoding unit that decodes the code data stored in the code memory 101, 104 is an inverse quantization unit that performs inverse quantization processing on the Huffman-decoded data in the Huffman decoding unit 102, and 105 is an inverse quantization unit. An IDCT processing unit that performs IDCT processing on the data dequantized by the quantization unit 104, and an image memory 106 that stores the image data restored by the IDCT processing by the IDCT processing unit 105.

General J stored in the code memory 101
The data structure of the PEG baseline encoding method and the structure of the Huffman code will be described. FIG. 2 is a diagram showing a data structure of code data for one page of the JPEG baseline coding method. FIG. 2 shows the case of the sequential mode and interleaved format, in which one frame is
There is also one scan.

From the upper side of FIG.
"I" is a marker indicating the start of the image. Continued "D
"HT" is a marker that defines the Huffman code, "DQT"
Is a marker that defines a quantization table, “SOF” is a marker that indicates the start of a frame, and the number of sub-scanning lines is
The number of main scanning pixels, sampling ratio, quantization table selector, etc. are designated. Note that the number of sub-scanning lines is "zero".
If is specified, the end of the image is indicated by the DNL marker.

Further, "SOS" is a marker indicating the start of scanning, and "DATA" is compressed code data. Further, although "EOI" is a marker indicating the end of the image, it also indicates the end of the frame and the end of the scan in FIG. And the encoding is 8x
The image data for one color of one block of eight sizes is used as a unit, and is performed by the processing procedure of quantization processing, zigzag scanning, and Huffman coding.

The marker code included in the code data is always added in byte units. The first of all marker codes is "FF" h ("h" represents hexadecimal number),
"XX" h ("XX" h is any 16 except "00" h
Represents a decimal number). Therefore, in the code data, "F
When it becomes F "h, the byte of" 00 "h is inserted next. Conversely, when" FF "h is found during decoding, if the next byte is" 00 "h, it can be determined that it is not a marker code. Also, in the final part of the image, bits less than the byte are filled with "1". At this time, when it becomes "FF" h, EOI marker is added after inserting "00" h next.

In the Huffman decoding unit 102, the code data stored in the code memory 101 and encoded by the JPEG baseline encoding system is decoded in block units and output to the inverse quantization unit 104. Then, the inverse quantization unit 104 performs inverse quantization processing, and the IDCT processing unit performs I
The image is subjected to DCT processing and stored in the image memory 106. That is, in the conventional Huffman decoding unit 102, the table for decoding from “DHT” is stored in the internal R of the Huffman decoding unit 102.
When it is created on the AM, the decoding process is performed based on this decoding table, and when the "EOI" marker added immediately after the last "DATA" of the page is detected, it is determined that the decoding of one block is completed, for example, "EOI flag". Turn on. Then, the inverse quantization unit 104 performs inverse quantization processing, and IDCT
The processing unit performs IDCT processing and stores it in the image memory 106. “EOI” is displayed when storage in the image memory 106 is complete.
The marker is confirmed, and since the “EOI” marker is on, the decoding process for one page ends.

[0008]

However, in the above-described conventional example, since the EOI flag is confirmed before the decoding of one page is completed for the code data to be decoded, all white, etc. When decoding one block of coded data whose length is short, there is a problem that the decoding process of one page may be completed before the decoding process of all blocks is completed. That is, since the detection time of the "EOI" marker is earlier than the decoding time of the final block of page 1, the decoding process may be terminated before the decoding of the code data is completed.

[0009]

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following structure as one means for solving the above-mentioned problems. That is, JP
A decoding unit for Huffman decoding the code data encoded by the EG baseline encoding method is provided, and the decoding unit recognizes the function of recognizing the EOI marker or the DNL marker in the data and the end in the main scanning direction. The decoding process for one page is completed on condition that the end of the main scanning direction is recognized and the EOI marker or the DNL marker is recognized in the decoding process.

Alternatively, a decoding unit for Huffman decoding coded data coded by the JPEG baseline coding method, counting the number of pixels in the main scanning direction of the coded data, and providing a carry signal at the end in the main scanning direction. The decoding unit has a function of recognizing the EOI marker or the DNL marker in the data, and the main scanning direction counter for outputting the EOI marker or the DNL marker in the decoding process. The decoding process for one page is completed under the condition that the carry signal is output.

Alternatively, a decoding unit for Huffman decoding coded data encoded by the JPEG baseline encoding method is provided, and the decoding unit has a function of recognizing an end in the main scanning direction and an end in the sub scanning direction. It has a recognition function, and finishes the decoding process of one page on condition that the end of the main scanning direction and the end of the sub scanning direction are recognized in the decoding process.

Further, a decoding unit for Huffman decoding the code data coded by the JPEG baseline coding method, counting the number of pixels of the code data in the main scanning direction, and carrying at the end in the main scanning direction. A main scanning direction counter that outputs a signal and a sub scanning direction counter that counts the number of lines in the sub scanning direction and outputs a carry signal at the end of the sub scanning direction are provided. The decoding process for one page is completed under the condition that the carry signal is output from the main scanning direction counter and the carry signal is output from the sub scanning direction counter.

[0013]

With the above structure, it is possible to prevent the decoding process for one page from ending before the decoding process for all blocks is completed, and a reliable decoding process is realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings.

[0015]

[First Embodiment] FIG. 1 is a block diagram showing the arrangement of a color image decoding apparatus according to the first embodiment of the present invention. In FIG. 1, the same components as those in FIG. 27 described above are denoted by the same reference numerals. In the figure, reference numeral 101 is a code memory for storing JPEG baseline encoded code data, 103 is a main scanning direction counter for counting the number of pixels in the main scanning direction, and a carry is carried out when the processing reaches the end in the main scanning direction. Output a signal. The counting of the number of pixels is performed on the decoded data. Reference numeral 104 is an inverse quantization unit that performs inverse quantization processing on the Huffman-decoded data by the Huffman decoding unit 110, 105 is an IDCT processing unit that performs IDCT processing on the data inversely quantized by the inverse quantization unit 104, 106 Is the ID
An image memory that stores image data that has been IDCT processed and restored by the CT processing unit 105, and 110 is a code memory 101.
Is a Huffman decoding unit that decodes the code data stored in.

The data structure of the JPEG baseline coding system and the structure of the Huffman code in this embodiment are the structures shown in FIG. The encoding by the JPEG baseline encoding method is performed by the processing procedure of the quantization process, the zigzag scan, and the Huffman encoding in units of image data of one color of one block of 8 × 8 size. When encoding image data represented in a color space composed of a luminance component and a color difference component such as YUV, the sub-sample ratio is Y: U: V = in the sequential mode of the JPEG baseline system and the interleaved format. 1: 1: 1
In the order of YUVYUV ..., and when the sub-sample ratio is Y: U: V = 2: 1: 1, YYUVY
In the order of YUV ..., the sub-sample ratio is Y: U: V =
In the case of 4: 1: 1, YYYYUVYYYYUV ...
The code data is formed by interleaving the data of each color for each block in the order of.

FIG. 3 is a diagram showing an example of one block. At the time of encoding, DCT processing is first performed. DC
The calculation method of T is based on the following formula.

[0018]

[Equation 1] However, when u = 0 and v = 0, C (u), C (v) =
(1 / √2) In other cases C (u), C (v) = 1. Next, the quantization process is performed. The quantization table is suitable for the luminance component and the color difference component by the above-mentioned “DQT” marker. Defined quantization table. In addition, the quantization table can be switched for each page to control the compression rate and the image quality.

FIG. 4 is a quantization table for the luminance component, and FIG.
Is a quantization table for color difference components, which is quantized by dividing each coefficient after DCT processing by a threshold value at a corresponding position in the quantization table. The Huffman code defines a Huffman table suitable for each of the luminance component and the color difference component by the above-mentioned “DHT” marker.

In the quantized data, the value at the position of "0" in FIG. 3 is called a DC coefficient and represents the average value of the data for one block. Further, the values at the positions of "1" to "63" are called AC coefficients. In Huffman coding, different processing is performed on the DC coefficient and the AC coefficient. The DC coefficient is Huffman-coded for the difference from the DC coefficient of the immediately preceding block of the same color.

FIG. 6 is a table for grouping DC coefficients, which are divided into groups SSSS from "0" to "11" according to the difference value of the DC coefficients. FIG. 7 shows the luminance component D
The code of the C difference, FIG. 8 is an example of the code of the DC difference of the color difference component, and is encoded by the code corresponding to the group SSSS. Furthermore, the same number of additional bits as SSSS is added to indicate the DC difference value in each group.

The additional bits are sequentially assigned with the smallest value of each group being "0". For example SSSS
= 3, "-3" is "00" and "-2" is "0".
"1" and "2" are "10", and "3" is "11". D
Although the sign of the AC coefficient can be added after the sign of the C coefficient,
First, the C coefficients are rearranged one-dimensionally in the order of "1" to "63" shown in FIG. This is called zigzag scanning. The rearranged AC coefficients are coded as a set of consecutive zero coefficient runs NNNN and non-zero coefficients. Figure 9
Is a table for grouping AC coefficients, and groups SS from "1" to "10" depending on AC coefficients other than zero.
Divided into SS. It is encoded by a set of the zero run NNNN and the group number SSSS. When the zero run exceeds “15”, ZR is applied to 16 zero coefficients.
Attach L code. When the AC coefficient of “63” in FIG. 3 is zero, the encoding of one block is completed by the EOB code. When it is non-zero, EOB is not attached.

FIGS. 10 and 11 show examples of signs of AC coefficients of luminance components, and FIGS. 12 and 13 show examples of signs of AC coefficients of chrominance components. In addition, the code of the next block is continuously added after the bit where the code of the previous block is completed. However, the marker code is always added in byte units. The beginning of all marker codes is "FF" h
("H" represents a hexadecimal number), "XX" h ("XX" h
Represents any hexadecimal number other than "00" h).
Therefore, when "FF" h is obtained in the code data, the byte "00" h is inserted next. On the contrary, when decoding "FF"
When h is found, if the next byte is "00" h, it can be determined that it is not a marker code. In the final part of the image, bits less than the byte are filled with "1". At this time, when it becomes "FF" h, EOI marker is added after inserting "00" h next.

Next, the operation of the present embodiment shown in FIG. 1 for decoding the coded data thus coded and storing it in the image memory 106 will be described. The purpose of the apparatus of this embodiment is to store the J stored in the code memory 101 as described above.
That is, the code data encoded by the PEG baseline encoding method is decoded and stored in the image memory 106.

The Huffman decoding unit 110 in this embodiment
Are the "SOI", "DHT", "DQ" shown in FIG.
It has a function of reading and interpreting markers such as "T", "SOF", and "SOS". The "DHT" includes a Huffman code table, the "DQT" includes a quantization table, and the "SOF" includes image size information such as the number of pixels in the main scanning direction and the number of lines in the sub scanning direction.

First, the Huffman decoding unit 110 first reads "D
HT ”, the decoding tables shown in FIGS. 14 to 21 are created in the internal RAM of the Huffman decoding unit 110. FIG. 14 is a table for decoding the DC coefficient of the luminance component, FIG. 15 is a correspondence table between indexes and SSSS, and FIG.
17 is a table for decoding the AC coefficient of the luminance component, FIG. 17 is a table for correspondence between the index and NNNN / SSSS, FIG. 18 is a table for decoding the DC coefficient for the color difference component, FIG. 19 is a table for correspondence between the index and SSSS, and FIG. Is a table for decoding the AC coefficient of the color difference component, and FIG. 21 is an index and NNN.
N / SSSS correspondence tables are shown, and these tables are "D
HT ”.

FIG. 22 is a diagram showing an example of code data.
The data for the color difference component is shown in the last one block of the page, and an example of the data in which the "EOI" marker is added is shown immediately after. Further, in the following description, it is assumed that the DC component of the block immediately before the same color component as this block is “8”. In this embodiment, the longest Huffman code is 16 bits as shown in FIGS. Therefore, when decoding, 16-bit data is always prepared.

Since it is the DC component at the beginning, the data "111010" at the addresses "0" and "1" in FIG.
"0010100011" is loaded into the internal register. When fetching data from the code memory 101, the Huffman decoding unit 110 first recognizes whether it is a marker code. That is, it is compared whether it is "FF" h, and if the next byte is "00" h, it is part of the data.
If the value is other than "00" h, it is determined to be a marker code.

For example, "D9" h is an "EOI" marker, so the EOI flag is turned on. However, since the addresses "0" and "1" shown in FIG. 22 are not markers, the EOI flag is not operated.
Then, the 16-bit data stored in the internal register and the code word having the shorter code length in the table for decoding the DC coefficient of the color difference component shown in FIG. 18 are compared in order. The comparison is performed by subtracting the code word of FIG. 18 from the referred data, and when it becomes positive, it is determined that the code length is one code before that. In this way, addresses "0" and "1"
It can be seen that the data has a code length of 4, and the code is "1110". Therefore, here, the 16-bit internal register is shifted to the left by 4 bits, and it is changed to 4
Transfers the bit data. At this time, since the address 4 is not "FF" h, the flag is not operated. As a result, the internal register becomes "100010100011001.
1 ”.

Since the index is "4" from the table for decoding the DC coefficient of the color difference component shown in FIG.
It can be seen from the correspondence table between the index 9 and the SSSS that the group number SSSS is “4” by referring to the index 4. If the group number is "4", 4 additional bits are added, and the additional bit is "10".
00 ”.

FIG. 23 is a table showing the SSSS and the additional bits for the coefficients from "-15" to "15". From FIG. 23, it can be seen that the DC difference value is "8". Since the DC component of the previous block is "8", the DC component of this block is "16". If 4-bit data is further fetched from address 2 and the internal register is shifted by the additional 4-bit bits, the value of the internal register becomes "1010001100111011".

From the next, since it is an AC coefficient, comparison is performed using the table for decoding the AC coefficient of the color difference component of FIG. The code length is 4, but for the AC coefficient, the number of bits of the code length is extracted and subtracted, and the value obtained by adding the value to the index is added to the index and NNNN / S in FIG.
It is referred to as an index in the SSS correspondence table.
Now, since the first 4 bits of the internal register are "1010" and the code of code length 4 in FIG. 20 is also "1010", the difference is "zero". Therefore, the index and NNNN / SSSS correspondence table in FIG. It can be seen that the index in 1 refers to "3", NNNN is "zero", and SSSS is "3".

If 4 bits are fetched after checking whether the address 3 is "FF" h, the value of the internal register becomes "0011001110111101". Since the additional bits are the first three bits “001”, FIG.
It can be seen that the AC coefficient is "-6". Furthermore, when 3 bits are fetched from address 3 and the internal register is shifted, the value of the internal register becomes "1001111011110.
1001 ". Similarly, the code length is "3" and the difference is 1.
00-100 = 0, and referring to index 2,
It can be seen that NNNN is “zero” and SSSS is “2”. If 1 bit from address 3 and 2 bits from address 4 are fetched here, the value of the internal register is "1110111101".
001000 ".

Since the address 4 is not "FF" h, the flag is not operated. The additional bit is "11", 2 bits are fetched from address 4, and the internal register is "101".
1110100100011 ”. When the comparison is performed using the table for decoding the AC coefficient of the color difference component in FIG. 20, it can be seen that the code length is 4. The difference is 1011-1010 = 1
Therefore, referring to index 3 + 1 = 4 in the index and NNNN / SSSS correspondence table of FIG.
It can be seen that NNN = 1 and SSSS = 1. 4 bits are fetched from address 4 and the internal register reads "1101001.
000111111 ”, but the first 1 bit is an additional bit. Since NNNN is “1”, it can be seen that there is one AC coefficient of “zero”. The next AC coefficient is "1".

Here, 1 bit is fetched from address 5, and the value of the internal register is "101001000111".
1111 ", however, since the address 5 is" FF "h, the address 6 is" D9 "h. Therefore EOI
Since it is a marker, the EOI flag is turned on. When decoding is subsequently performed, the code length is "4" and the difference is "zero", so it can be seen that NNNN is "zero" and SSSS is "3". If 4 bits are fetched from the address 5 here, the internal register reads "010001111111111".
However, the first 3 bits are additional bits. Therefore, it can be seen that this AC coefficient is "-5". When 3 bits are fetched from address 5, the internal register will read "00
11111111111111 ". Comparing according to the table for decoding the AC coefficient of the color difference component in FIG. 20, the code length is “1”, NNNN = 0, SSSS =
It becomes 0. Since this is an EOB code, the Huffman decoding unit 110 ends decoding of the block.

When the decoded coefficients are arranged, the DC coefficient becomes "1".
6 ", AC coefficients are" -6 "," 3 "," 0 "," 1 ",
“−5”, “0”, ..., “0”. When arranged according to the order of FIG. 3, it becomes as shown in FIG. This data is sent to the dequantization unit 104 and dequantized. Inverse quantization is
It is performed by multiplying the quantization table for luminance shown in FIG. 4, the quantization table for color difference shown in FIG. 5, each coefficient after Huffman decoding, and the corresponding quantization coefficient in the quantization table.

When the inverse quantization process is completed in this way, the IDCT processing unit 105 then performs the IDCT process.
The IDCT processing method in the IDCT processing unit 105 is based on the following formula.

[0038]

[Equation 2] However, when u = 0 and v = 0, C (u), C (v) =
(1 / √2) In other cases C (u), C (v) = 1, and the decoded and IDCT-processed image data is stored in the image memory 106. When the processing up to this point is completed,
The main scanning direction counter 103 is incremented, but in this case, since it is the end in the main scanning direction, a carry signal is output from the main scanning direction counter 103.

When the carry signal from the main scanning direction counter 103 is output, the Huffman decoding unit 110 outputs the carry signal.
The EOI flag is checked, and if the EOI flag is turned on, the decoding process for one page ends. FIG. 22
In this example, since the EOI flag is turned on, the decoding process for one page ends. The above description is an example of the case where the number of sub-scanning lines is designated by the SOF marker, but when the number of sub-scanning lines is not designated by the SOF marker, that is, when the number of sub-scanning lines is set to "zero". In addition, the configuration of the code data is not the configuration shown in FIG. 2 described above but the configuration shown in FIG.

That is, in this case, the DNL marker is added immediately after "DATA". Therefore, the DNL marker is recognized after the decoding process of the coded data is completed, and the number of sub-scanning lines can be known here. Also in this case, the basic operation is almost the same as the above-described case where the number of sub-scanning lines is designated by the SOF marker, but the difference is that the Huffman decoding unit 110 described above E
A DNL flag is provided in addition to the OI flag. When two conditions, that is, the carry output of the main scanning direction counter carry and the EOI flag are turned on, are satisfied as the end condition of the decoding process of the code data of one page. However, the condition of the carry output of the main scanning direction counter and the EOI
This is a condition that two conditions, that is, either the flag ON or the DNL flag ON is recognized, are satisfied.

As described above, according to this embodiment, it is possible to prevent the decoding process for one page from ending before the decoding process for all blocks is completed, and it is possible to realize a reliable decoding process. Become.

[0042]

Second Embodiment In the above description, the end condition of the decoding process of the coded data of one page is determined when the two conditions of the output of the carry of the main scanning direction counter and the ON of the EOI flag are satisfied, or An example has been described in which two conditions, that is, the condition that the carry of the scanning direction counter is output and the condition that either the EOI flag is turned on or the DNL flag is turned on are recognized, are satisfied. However, the present invention is not limited to the above examples, and further, SOF
A sub-scanning direction counter that outputs a carry signal when data for a line in the sub-scanning direction designated by a marker is restored is provided. In addition to the EOI flag being on and the main scanning direction counter outputting a carry, the sub-scanning A condition that the direction counter outputs a carry may be added. By doing so, a more reliable decoding process becomes possible. A second embodiment according to the present invention having such a configuration will be described below.

FIG. 26 is a block diagram showing the configuration of the second embodiment according to the present invention. In FIG. 26, the same components as those of the first embodiment shown in FIG.
Detailed description is omitted. In FIG. 26, reference numeral 107 denotes a sub-scanning direction counter, which outputs a carry signal when the data for the sub-scanning direction line designated by the SOF marker is restored. A Huffman decoding unit 120 decodes the code data stored in the code memory 101. In the second embodiment having the above configuration, the basic operation is the same as that of the above-described first embodiment, and therefore, only the part different from the above-mentioned first embodiment will be described.

The Huffman decoding unit 120 of the second embodiment is
The termination conditions of the decoding process of the coded data for one page of the Huffman decoding unit 110 shown in FIG. 1 described above are set to two points, that is, the EOI flag is on and the carry from the main scanning direction counter 103 is recognized. In addition, the condition that the sub-scanning direction counter 107 outputs a carry and recognizes it is added.

By providing the sub-scanning counter 107 in this way, more reliable decoding processing becomes possible. The present invention may be applied to a system including a plurality of devices or an apparatus including one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0046]

As described above, according to the present invention, it is possible to prevent the decoding process for one page from ending before the decoding process for all blocks is completed, and it is possible to perform a reliable decoding process. A device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of code data for one page of the JPEG baseline encoding method.

FIG. 3 is a diagram showing a configuration example of one block of encoded data processed in this embodiment.

FIG. 4 is a diagram showing an example of a quantization table of luminance components in the present embodiment.

FIG. 5 is a diagram showing an example of a quantization table of color difference components in the present embodiment.

FIG. 6 is a diagram showing a table showing groups of DC coefficients in the present embodiment.

FIG. 7 is a diagram showing a table showing signs of DC differences of luminance components in the present embodiment.

FIG. 8 is a diagram showing a table showing signs of DC differences of color difference components in the present embodiment.

FIG. 9 is a diagram showing a table showing groups of AC coefficients in the present embodiment.

FIG. 10 is a diagram showing a table showing the signs of AC coefficients of luminance components in the present embodiment.

FIG. 11 is a diagram showing a table showing signs of AC coefficients of luminance components in the present embodiment.

FIG. 12 is a diagram showing a table showing signs of AC coefficients of color difference components in the present embodiment.

FIG. 13 is a diagram showing a table showing signs of AC coefficients of color difference components in the present embodiment.

FIG. 14 is a diagram showing an example of a table for decoding the DC coefficient of the luminance component in the present embodiment.

FIG. 15 is a diagram showing a correspondence table between indexes and SSSSs in the present embodiment.

FIG. 16 is a diagram showing an example of a table for decoding AC coefficients of luminance components in the present embodiment.

FIG. 17 shows an index and NNNN in the present embodiment,
It is a figure showing the correspondence table of SSSS.

FIG. 18 is a diagram showing an example of a table for decoding the DC coefficient of the luminance component in the present embodiment.

FIG. 19 is a diagram showing a correspondence table between indexes and SSSSs in the present embodiment.

FIG. 20 is a diagram showing an example of a table for decoding AC coefficients of luminance components according to the present embodiment.

FIG. 21 is an index and NNNN in the present embodiment;
It is a figure showing the correspondence table of SSSS.

FIG. 22 is an example of code data in the present embodiment.

FIG. 23 is a diagram showing a table showing SSSS and additional bits corresponding to coefficients “-15” to “15” in the present embodiment.

FIG. 24 is a diagram showing coefficients obtained by decoding the code data shown in FIG. 22 in the present embodiment.

[Fig. 25] Fig. 25 is a diagram illustrating the configuration of code data for one page according to the JPEG baseline encoding method.

FIG. 26 is a block diagram showing a configuration of a second exemplary embodiment according to the present invention.

FIG. 27 is a block diagram showing a configuration of a conventional decoding device.

[Explanation of symbols]

 Reference Signs List 101 code memory 102, 110, 120 Huffman decoding unit 103 main scanning direction counter 104 inverse quantization unit 105 IDCT processing unit 106 image memory 107 sub-scanning counter

Claims (4)

[Claims] 1. A decoding unit for Huffman decoding code data encoded by the JPEG baseline encoding method, wherein the decoding unit is an EOI marker or D in the data.
It has a function of recognizing the NL marker and a function of recognizing the end in the main scanning direction, and finishes the decoding process of one page on condition that the end of the main scanning direction is recognized and the EOI marker or the DNL marker is recognized in the decoding process. An image processing device characterized by: 2. A decoding unit for Huffman decoding code data encoded by the JPEG baseline encoding method, counting the number of pixels in the main scanning direction of the code data, and carrying at the end in the main scanning direction. A main scanning direction counter that outputs a signal, wherein the decoding unit is an EOI marker or D in the data.
An image processing characterized by having a function of recognizing an NL marker, and terminating the decoding processing for one page on the condition that the EOI marker or the DNL marker is recognized in the decoding processing and the carry signal is output by the main scanning direction counter. apparatus. 3. A decoding unit for Huffman decoding code data encoded by the JPEG baseline encoding method, wherein the decoding unit has a function of recognizing an end in the main scanning direction and an end in the sub-scanning direction. An image processing apparatus having a recognition function, wherein the decoding process for one page is terminated on condition that the end of the main scanning direction and the end of the sub scanning direction are recognized in the decoding process. 4. A decoding unit for Huffman decoding code data coded by the JPEG baseline coding method, counting the number of pixels in the main scanning direction of the code data, and carrying at the end in the main scanning direction. A main scanning direction counter that outputs a signal, and a sub-scanning direction counter that counts the number of lines in the sub-scanning direction and outputs a carry signal at the end of the sub-scanning direction, wherein the decoding unit is used in the decoding process. An image processing apparatus, characterized in that the decoding process for one page is terminated under the conditions of the carry signal output by the main scanning direction counter and the carry signal output by the sub scanning direction counter.