JP4986906B2 - Decoding device, decoding method, program, and recording medium - Google Patents

Description

  The present invention relates to a JPEG2000 decoding apparatus and decoding method, and more particularly to control of reconstruction value addition processing.

As a next-generation high-efficiency encoding system for image data, JPEG2000 has been formulated by ISO (International Organization for Standardization) and ITU-T (International Telecommunication Union Telecommunication Standardization Sector). JPEG2000 has superior functions compared to the current mainstream JPEG.
In JPEG2000 Part I (ISO / IEC15444-1), in the decoding process, if the value of each quantized wavelet coefficient is not “0”, an arbitrary r (0 ≦ r <1) is reset to the lowest order. It is specified to be added as a construction value. This is to mitigate the effect of rounding to reduce the absolute value of the wavelet coefficient in the quantization during the encoding procedure.

  Conventionally, a truncation point is determined for each bit plane, and a reconstruction value addition process is performed (see, for example, Patent Document 1). However, when a truncation point is in the coding pass unit, there is a problem in that the bit plane of the truncation point cannot be accurately determined and some image quality degradation occurs.

  In Patent Document 1, the value of the parameter r to be added corresponding to the attention coefficient is determined based on the subband to which the quantized attention coefficient belongs and the coefficient in the vicinity of the attention coefficient. This value is added to each quantized wavelet coefficient.

JP 2003-189107 A

  As described above, when the truncation point is determined by the bit plane unit and the reconstruction value is added, if the truncation point is in the encoding pass unit, the bit plane that is the truncation point is accurately set. There is a problem that the image quality cannot be determined and some image quality degradation occurs.

  As a method for solving this problem, decoding is performed on the sub-bit plane to be decoded and r is added, and when the sub-bit plane to be decoded is moved to the next sub-bit plane, the previously added r is subtracted. A method of performing reconstruction value addition processing on all sub-bit planes, such as decoding from (1) and adding r again, can be considered. However, this method repeats addition and subtraction of reconstruction values, and has another problem that the processing speed is reduced.

  Therefore, an object of the present invention is to accurately control the execution of reconstruction value addition processing in a JPEG2000 decoding apparatus or method, and to enable suppression of image quality deterioration and high-speed processing.

The invention of claim 1 is a JPEG2000 decoding apparatus, comprising: a determination unit that determines whether or not the number of remaining sub-bitplanes is 1 or more and a set value or less before the encoding pass process in the entropy decoding process. The determination unit determines that the number of remaining sub-bitplanes is greater than or equal to 1 and less than or equal to a set value as a necessary condition for performing reconstruction value addition processing after encoding pass processing, and the set value Is a decoding device characterized in that is set to 3 .

The invention of claim 2 is a JPEG2000 decoding device, comprising: a determination unit that determines whether or not the number of remaining sub-bitplanes is 1 or more and a set value or less before the encoding pass process in the entropy decoding process. The determination unit determines that the number of remaining sub-bitplanes is 1 or more and a setting value or less as a necessary condition for performing a reconstruction value addition process after the encoding pass process, and the setting value is The decoding apparatus is characterized in that the Magnitude Refinement path and the Cleanup path are set to 3 and the Significant Propagation path is set to 4.

The invention according to claim 3, in the decoding apparatus of the invention of claim 1, when the remaining sub-bit plane number is zero, further comprising means for determining the necessity of the addition process of reconstruction value, said means Thus, when it is determined that the addition process of the reconstruction value is necessary, the addition process of the reconstruction value is performed.

The invention of claim 4 is a JPEG2000 decoding method, comprising a determination step of determining whether the number of remaining sub-bitplanes is not less than 1 and not more than a set value before the encoding pass process in the entropy decoding process, that the remaining sub-bit plane number is determined to be less than 1 and not more than the set value by the determination step, and a necessary condition for carrying out addition processing of the reconstruction value after processing of coding pass, the set value The decoding method is characterized in that it is set to 3 .

The invention of claim 5 is a JPEG2000 decoding method, comprising a determination step of determining whether the number of remaining sub-bitplanes is not less than 1 and not more than a set value before processing of an encoding pass in an entropy decoding process, The determination step determines that the number of remaining sub-bitplanes is 1 or more and a setting value or less as a necessary condition for performing the addition processing of the reconstruction value after the processing of the coding pass, and the setting value is The decoding method is characterized in that the Magnitude Refinement path and Cleanup path are set to 3 and the Significant Propagation path is set to 4.

According to a sixth aspect of the present invention, in the decoding method according to the fourth aspect of the present invention, when the number of remaining sub-bitplanes becomes zero, the method further comprises the step of determining whether or not the addition processing of the reconstruction value is necessary. Thus, when it is determined that the addition process of the reconstruction value is necessary, the addition process of the reconstruction value is performed.

The invention of claim 7 is a program causing a computer to function as a decoding device of the present invention of any one of claims 1 to 3.

The invention according to claim 8 is a recording medium on which a program for causing a computer to function as the decoding device according to any one of claims 1 to 3 is recorded.

  According to the decoding apparatus or the decoding method of the present invention, it is possible to suppress image quality deterioration by executing necessary reconstruction value addition processing while minimizing unnecessary processing that causes a decrease in processing speed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a JPEG2000 decoding apparatus. This decoding apparatus includes code data input means 1, header analysis means 2, entropy decoding means 3, scalar inverse quantization means 4, inverse wavelet transform means 5, color conversion means 6, DC level shift means 7 and image data output means. 8 is provided. Of these, the scalar inverse quantization means 4, the color conversion means 6, and the DC level shift means 7 are optional and can be omitted.

  The overall operation of this decoding apparatus will be described. First, code data of an image compression-encoded according to the JPEG2000 standard is input by the code data input means 1 using a file system or network means. A main header and a tile header are added to the code data, and the header analysis means 2 reads and analyzes these headers.

  Here, the main header stores information about the size of the image, the size of the tile, the offset of the image position, the offset of the tile position, the number of sample bits per pixel, the number of components such as RGB, and the like. . The tile header stores a tile number, a tile size, and the like, and can specify an encoding style, a quantization style, and the like.

  The entropy decoding unit 3 performs entropy decoding of the code data using the analysis result of the header analysis unit 2 and creates a scalar quantized coefficient sequence from the output bit sequence. The scalar inverse quantization unit 4 converts the coefficient sequence created by the entropy decoding unit 3 into a predetermined number in the JPEG 2000 standard based on the quantization style specified by the main header and the tile header analyzed by the header analysis unit 2. Wavelet coefficients are generated by inverse quantization using a calculation formula. Note that the wavelet coefficients generated by the wavelet transform are not necessarily quantized at the time of encoding, and in this case, the inverse quantization by the scalar inverse quantization means 4 is not performed.

  The inverse wavelet transform unit 5 performs inverse wavelet transform on the wavelet coefficient obtained by the scalar inverse quantization unit 4 based on the number of decompositions of the coding style specified by the main header or tile header, and image data in the YUV color space Create The color conversion unit 6 converts the image data obtained by the inverse wavelet conversion unit 5 from the YUV component to the RGB component according to the analysis result of the header analysis unit 2. However, in the case of code data of a monochrome image or when color conversion is not performed at the time of encoding, the color conversion means 6 does not operate.

  The DC level shift means 7 shifts the DC level of the RGB component obtained by the color conversion means 6. The DC level shift is a shift so that the dynamic range is centered on the value 0 at the time of encoding, and is returned to the original at the time of decoding. For example, if a certain input image data is represented by 8 bits, this data takes any value from 0 to 255. By shifting the DC level, the value of this data is centered on 0. The value can be set to -128 to 127. As described above, the reason for performing the DC level shift is that the coefficient after frequency conversion is encoded by being divided into positive and negative signs and absolute values, and therefore the data arrangement with the zero value as a reference is more efficient in encoding. Because it becomes higher. The image data output means 8 is a means for outputting the image obtained by the DC level shift means 7.

  In JPEG2000, a data truncation process called “post-quantization” (truncation) is performed (not always performed) on data after coefficient bit modeling at the time of encoding.

  FIG. 2 is an explanatory diagram of this post-quantization. Shown in this figure are some bit-plane wavelet coefficients included in one code block. In this example, the wavelet coefficients of “16, 64, 88, 32, 0, 0, 0, 112” converted into bit planes are shown, the number of bits of the coefficients is 9, and the number of 0 bit planes is 2. . As the coding pass, there are a Significant Propagation pass (abbreviated as S pass), a Magnitude Refinement pass (abbreviated as R pass), and a Cleanup pass (abbreviated as C pass), and the boundary of each coding pass becomes a truncation point. A bit plane divided by three paths is called a sub-bit plane. The values of all bit data below the truncation point are “0”, and the processing is substantially the same as that of truncation. JPEG2000 intends efficient compression coding by such a truncation process. Data such as the number of bits of the coefficient, the number of zero bit planes, and the number of coding passes is stored in header information called packet header information.

  In this way, when post-quantization is performed, all the lower-order bit data from the truncation point is uniformly zero, so when this is decoded and reproduced as it is, there is a part of the reproduced image that is uncomfortable or unclear. May be included, resulting in image quality degradation. Therefore, image quality deterioration is suppressed by adding a reconstruction value to lower-order bit data than the cut-off point.

  As described above, conventionally, the reconstruction value is added by a truncation point in units of bit planes. However, when the truncation point is in units of each path, the bit plane that becomes the truncation point cannot be determined.

  Even in such a case, the present invention accurately determines a bit plane that is a truncation point, performs a necessary reconstruction value addition process to suppress degradation of the image quality of the decoded image, and reduces unnecessary processing. It is intended to speed up the processing.

  Here, the operation related to the entropy decoding means 3 will be described in more detail. The header analysis means 2 identifies the head address of the packet data by decoding the COD marker. Based on the head address of the specified packet data, the code data CD of the first encoding pass is taken out, and the S pass, R pass, and C pass streams are sequentially input to the entropy decoding means 3. The entropy decoding means 3 receives the code data CD and the context label CX as inputs, and sequentially decodes them in the order of the input encoding passes. The decision D output from the entropy decoding means 3 is output to the scalar inverse quantization means 4.

  The context label CX is determined by coefficient bit modeling processing at the time of decoding in JPEG2000. The coefficient bit modeling process at the time of decoding is a process of determining the context required for the arithmetic decoding while updating the peripheral information using the decoding result by the entropy decoding means 3. Hereinafter, the coefficient bit modeling process at the time of decoding will be described with reference to FIGS.

  The subband image extracted from the code stream by the header analysis unit 2 is divided into small areas called code blocks, and the code block is a unit of decoding processing. The subband image is an LL subband having a low frequency component in both the x and y directions of the original image, has a low frequency component in any one direction of x and y, and has a high frequency component in the other direction. HL and LH subbands, and HH subbands having high frequency components in both x and y directions. The size of the code block is an integer value of a power of 2 in which the height and width are in the range of 22 to 210, and the standard defines that the sum of the height and width indices is 12 or less.

  FIG. 3 is a diagram for explaining a bit plane formed by slicing a code block for each bit. The bit plane of the code block is composed of a Sign plane that stores the sign of the quantized value of the wavelet transform coefficient, and a plurality of planes from MSB to LSB that give the absolute value of the quantized value of the wavelet transform coefficient. . The entropy decoding means 3 selects bit planes in order from the upper bits, and performs decoding processing of each coefficient on the bit plane in units of bit planes.

  FIG. 4 is a diagram for explaining the scanning order when the coefficients on the bit plane are decoded. The bit plane is divided into stripes of 4 pixels in length, and is scanned and decoded in units of stripes. The width of each stripe is the width of the code block, which is 32 pixels in this example. The total number of stripes is 8.

  In each stripe, as indicated by the arrows, the vertical four pixels in the first column are scanned in order from the top, and the decoding process proceeds one pixel at a time, and then the vertical four pixels in the second column are scanned in the same direction. Repeat until the last column. When the decoding process is completed up to the end of the stripe, scanning is performed in the same manner from the leading coefficient of the next stripe, the decoding process is performed, and the process is repeated until the last line of the code block. Note that the decoding of the Sign plane storing the sign of the coefficient is appropriately performed when decoding the plane corresponding to the absolute value portion of the coefficient.

  Each coefficient in the code block is identified in two states: significant or insignificant. 1 is assigned if significant, 0 is assigned if not significant, and the significance state of each coefficient is identified by a binary value. At the start of decoding, all coefficients in the code block are not significant.

  Here, the coefficient is significant means a state in which the quantized value of the focused wavelet transform coefficient is known to be not “0” from the results of the decoding processing so far. In other words, it means the state of the wavelet transform coefficient in which the bit of “1” is found while decoding while scanning in units of stripes sequentially from the upper bit plane. Also, the coefficient is not significant means a state where the quantized value of the focused wavelet transform coefficient is “0” or remains “0”. In other words, it means the state of the wavelet transform coefficient in which the bit “1” has not yet been found during the sequential decoding from the upper bit plane.

  In the coefficient bit modeling process, the context is determined for each coefficient bit based on the significance state of the coefficient around the coefficient of interest on the bit plane. FIG. 5 is a diagram illustrating eight neighboring coefficients adjacent to the periphery of the coefficient X to be decoded on the bit plane (hereinafter referred to as the current coefficient X). The eight neighboring coefficients are two coefficients h0 and h1 adjacent to the current coefficient X in the horizontal direction, two coefficients v0 and v1 adjacent in the vertical direction, and four coefficients d0 to d3 adjacent in the oblique direction. It consists of.

  Since each of the eight neighboring coefficients in FIG. 5 can take two states, which are significant or not significant, there can be 256 contexts as a combination with respect to the current coefficient X. It is aggregated into 19 types of contexts using sex and the like, and these contexts are identified with labels of 0-18. If any neighborhood coefficient is located outside the code block being processed, the neighborhood coefficient is regarded as insignificant and processed.

  Each coefficient bit in the bit plane is decoded based on one of three types of encoding passes, that is, an S pass (significance propagation pass), an R pass (magnitude refinement pass), and a C pass (cleanup pass). One bit plane is divided into three sub-bit planes as three types of encoding passes. Insignificant coefficients that are present in the vicinity in the S pass are decoded, coefficients that are significant in the R pass are decoded, and the remaining coefficients are decoded in the C pass.

  Each coding pass of the S pass, the R pass, and the C pass has a large contribution to the image quality in this order. Each coding pass is executed in this order, and the context of each coefficient is determined in consideration of information on neighboring coefficients. Hereinafter, a specific processing procedure in each coding pass will be described.

  First, the S pass process will be described. When the current coefficient X is insignificant in scanning in each stripe of the bit plane, and at least one of the eight neighboring coefficients adjacent to the current coefficient X is significant, the current coefficient X Is selected as an S pass processing target. In other cases, it is not an S pass processing target. A coefficient to be decoded in the S pass is a coefficient that is most likely to be significant in the bit plane.

  In the coefficient bit modeling process, for the current coefficient X, Σhi (= h0 + h1) that gives the number of significant coefficients of the two neighboring coefficients h0 and h1 in the horizontal direction, and two neighboring coefficients v0, Σvi (= v1 + v2) which gives the number of significant coefficients in v1, and Σdi (= d1 + d2 + d3 + d4) which gives the number of significant coefficients among the four neighboring coefficients d0, d1, d2 and d3 in the diagonal direction Ask for.

  FIG. 6 is a diagram for explaining a context classification table in the S pass. This context table shows the number of neighborhood coefficients Σhi, Σvi that are significant in the horizontal, vertical, and diagonal directions depending on whether the code block being processed belongs to the LH / LL subband, HL subband, or HH subband. , Σdi and nine kinds of context labels CX identified by labels 0 to 8 are associated with each other. With reference to this context classification table, the coefficient to be processed in the S path is set to one of nine types of contexts according to the combination of the directionality of the frequency component of the subband and the number of neighboring coefficients Σhi, Σvi, and Σdi. Classification is performed, and a corresponding context label CX is determined (context estimation).

  In the S pass, when the value of the bit of the current coefficient X is “1”, the significance state of the current coefficient X is changed from “not significant” to “significant”. When the current coefficient X becomes significant, the polarity bit indicating the sign of the current coefficient X is subsequently decoded.

  The context for the polarity bit takes two steps as described below, based on the significance state of the two neighboring coefficients v0, v1 in the vertical direction and the two neighboring coefficients h0, h1 in the horizontal direction and the positive and negative polarity values. Determined by

  FIG. 7 is a diagram for explaining a vertical index and a horizontal index table for determining the context of the polarity bit. For context estimation, it is first determined whether each of the two vertical neighborhood coefficients v0 and v1 is a positive significant coefficient, a negative significant coefficient, or a nonsignificant coefficient. Referring to the table of FIG. 7, any value of “0”, “1”, “−1” is assigned to the vertical index v. Similarly, any value of “0”, “1”, and “−1” is assigned to the horizontal index h with reference to the table of FIG. 7 for the neighborhood coefficients h0 and h1 in the horizontal direction.

  FIG. 8 is a table in which combinations of horizontal indices h and vertical indices v are associated with context labels CX for five types of polarity bits identified by labels 9 to 13. In the coefficient bit modeling process, referring to the table of FIG. 8, the polarity bits are classified into one of five types of contexts according to the combinations of the obtained horizontal index h and vertical index v, and the corresponding context label CX is determined. Is done.

  Next, R path processing will be described. When it is determined that the current coefficient X is already significant, the current coefficient X becomes an R path processing target in the bit plane being processed. However, a coefficient that has changed to a significant state in the immediately preceding S pass in the bit plane is not processed. The R-pass decoding process has a role of increasing the accuracy of the coefficients decoded in the S-pass.

  FIG. 9 is a diagram showing a context classification table in the R path. In the R path, the value of Σhi + Σvi + Σdi indicating the number of significant coefficients is obtained from eight neighboring coefficients with respect to the current coefficient X, and whether or not the current coefficient X becomes significant in the bit plane one level above, in other words, It is determined whether or not the R path is the first path after the current coefficient X has changed from a non-significant state to a significant state. Based on these results, as shown in FIG. Are classified into three types of contexts identified by the label, and the corresponding context label CX is determined.

  Finally, the C pass process will be described. The C path is used when the current coefficient X does not correspond to either the S path or the R path. In the C pass, run length decoding or decoding processing referring to the values of eight neighboring coefficients as in the S pass is performed. In the C pass, the process proceeds while determining whether to perform run-length decoding.

  FIG. 10 is a diagram illustrating a context classification table in the C path. In the C path, all four consecutive coefficients in the vertical direction are not significant, that is, all the vertical columns in the stripe belong to the C path, and the eight neighboring coefficients for all the four coefficients are also significant. It is determined whether or not the condition that there is no coefficient is. When this condition is satisfied, the decoding process is performed in the run length mode, and the context label CX is 17. If this condition is not met, there is at least one significant coefficient among the four consecutive coefficient values in the vertical direction. Therefore, the position of the first significant coefficient is determined using the UNIFORM context, and the context label at this time CX is 18. The same processing as in the S pass is performed for all remaining coefficients.

  As described above, in the coefficient bit modeling process, the context label CX of each coefficient on the bit plane is determined using any one of the S pass, R pass, and C pass.

  Now, according to the present invention, the entropy decoding means 3 is provided with a determination means for determining whether or not the number of remaining sub-bitplanes is not less than 1 and not more than a set value before processing the coding pass in the entropy decoding process. Thus, the determination means that the number of remaining sub-bitplanes is determined to be 1 or more and less than or equal to the set value is set as a necessary condition for performing reconstruction value addition processing after encoding pass processing. According to one aspect of the present invention, the set value is set to 3 for the S, R, and C paths. According to another aspect, the set value is set to 3 for the R path and the C path, and is set to 4 for the S path. According to another aspect, the set value is set to 3 for the S, R, and C paths, and whether or not addition processing of reconstruction values is necessary when the number of remaining sub-bitplanes = 0. A means for determining is further provided, and when the means determines that it is necessary, an addition process of the reconstruction value is performed.

  Examples of these aspects will be described in detail below.

  An embodiment in which the set value to be compared with the number of remaining sub-bitplanes is set to 3 for the S, R, and C paths will be described.

  FIG. 11 is a flowchart for explaining the flow of a decoding process of encoded data in the entropy decoding unit 3. Here, the processing content will be described along the flowchart of FIG. 11 by taking the code data shown in FIG. 14 as an example.

  In FIG. 11, steps S1701 and S1716 correspond to the determination means (process) for the number of remaining sub-bitplanes for the C path, and step S1706 corresponds to the determination means (process) for the number of remaining sub-bitplanes for the S path. Step S1711 corresponds to determination means (process) for the number of remaining sub-bitplanes for the R path. However, it is clear that the number of remaining sub bit planes is 1 or more in step 1701, and that the number of remaining sub bit planes is checked to be 1 or more in steps S1704, S1709, and S1714. In steps S1701, S1706, S1711, and S1716, it is determined whether the number of remaining sub-bitplanes is 1 or more and 3 (set value) or less.

  FIG. 14 shows a state in which the code data is divided into sub-bit planes. In this example, code data of 03 → 15 → 24... Are sequentially arranged, nine sub bit planes are discarded, and the number of remaining sub bit planes is four. Here, the number of remaining sub-bit planes is the number of remaining sub-bit planes to be decoded by the encoding pass.

  The coding pass in the coded data is input in order of 03 → 15 → 24... And processed in the flow described below. For example, “03” is the C path, C path, “15” is the C path, S path, “24” is the C path, and R path is input in this order.

  The code data “03” will be described. First, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1701). If the number of remaining sub-bitplanes ≦ 3 (S1701, Y), the C path decoding process is performed and the r value is added (S1702).

  Here, since the number of remaining sub-bitplanes = 4 (S1701, N), the C path decoding process is performed and the r value is not added (S1703). The number of remaining sub-bitplanes was 3.

  Next, it is determined that the number of remaining sub bit planes> 0 (S1704). Here, since the number of remaining sub-bitplanes = 3> 0, it is determined whether the next coding pass is the S pass (S1705).

  Here, it is not the S path. The number of remaining sub-bitplanes is 2. It is determined whether the number of remaining sub bit planes> 0 (S1709). Here, since the number of remaining sub bit planes = 2> 0, it is determined whether the next coding pass is an R path (S1710). ). Here, it is not the R path. The number of remaining sub-bitplanes is 1.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1714). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is a C pass (S1715).

  Here, since it is the C path, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1716). Here, it is the C path (S1715, Y), and the number of remaining sub-bitplanes ≦ 3 is determined (S1716). Since the number of remaining sub-bitplanes = 1 ≦ 3, the C-pass decoding process is performed and the r value is added (S1717).

Here, the addition method of the r value is as follows. r is 0 ≦ r <1, and r · 2 ^ (the number of bit planes−the number of decoded bit planes) in the least significant bit plane to be processed
Is added. When r is 3/8, the following values are added.
Addition value = r · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
When the decoded value is 0, no addition is performed. Here, since the decoded value is 0, no addition is performed.

  Since the process of step S1717 was performed, the number of remaining sub-bitplanes became zero. It is determined whether or not the number of remaining sub-bit planes> 0 (S1704), but the process ends because the number of remaining sub-bit planes = 0.

  Thus, since the first code data “03” is completed, the next code data (“15”) is processed in the same manner as described above. The initial number of remaining sub-bitplanes is four.

  First, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1701). Here, since the number of remaining sub-bitplanes = 4, the C-pass decoding process is performed, and the r value is not added (S1703). As a result, the number of remaining sub-bitplanes is three.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1704). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 3), it is determined whether the S path is used (S1705). Here, since it is the S path, it is determined whether or not the number of remaining sub-bitplanes ≦ 3 (S1706).

  Here, since the number of remaining sub-bitplanes ≦ 3, the S-pass decoding process is performed, and the r value is added (S1707). The number of remaining sub-bitplanes is 2.

The r value addition method here is as follows. r is 0 ≦ r <1, and r · 2 ^ (the number of bit planes−the number of decoded bit planes) in the least significant bit plane to be processed
Is added. When r is 3/8, the following values are added.
Addition value = r · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
When the decoded value is 0, no addition is performed. Before adding, it is determined whether or not a bit exists in a bit plane below the least significant bit plane, and if it exists, the added value is added after subtracting the bit. Here, it is 01000, and there is no bit in the bit plane below the least significant bit plane (000), so the subtraction is not performed and the addition is performed as it is. Therefore, it becomes 01011 after the addition.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1709). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 2), it is determined whether the next coding pass is an R pass (S1710).

  Here, it is not the R path. The number of remaining sub-bitplanes is 1. It is determined whether the number of remaining sub bit planes> 0 (S1714). Since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is a C pass (S1715).

  Here, it is not the C path. The number of remaining sub-bitplanes is zero. It is determined whether the number of remaining sub bit planes> 0 (S1704). Since the number of remaining sub-bitplanes is not> 0, the process ends (S1719).

  The second code data “15” is completed. The next code data “24” is processed in the same manner as described above. The same processing is performed until all encoded data to be input is completed.

  Here, in steps S1701, S1706, S1711, and S1716, the number of remaining sub-bit prelanes, which is a necessary condition for performing the addition processing of the reconstruction value after the coding pass process, is 1 or more and 3 or less. Is judged. Since each code data exists in one of the S, R, and C paths, it is assumed that the number of remaining sub-bitplanes is 1 or more and 3 or less as a necessary condition for performing the addition processing of reconstruction values. It is possible to add reconstruction values only to the upper three sub-bit planes from the least significant sub-bit plane, reduce wasteful processing, reliably suppress image quality degradation, and achieve high-speed processing.

  In the example of FIG. 14, the truncation point is in the bit plane unit. Next, a case where the truncation point as shown in FIG. 16 is in encoding pass units (subbit plane units) will be described with reference to the flowchart of FIG. In the example of FIG. 16, seven sub-bit planes below the cut-off point are cut off, and the number of remaining sub-bit planes is 6.

  First, since the number of remaining bit planes of the code data “03” is 6 (S1701, N), the C path decoding process is performed (S1703). This left 5 sub-bitplanes.

  The number of remaining sub-bitplanes> 0 (S1704, Y), and the next coding pass is not the S pass (S1705, N). The number of remaining sub-bitplanes is 4.

  The number of remaining sub-bitplanes> 0 (S1709, Y), and the next coding pass is not an R pass (S1710, N). Here, the number of remaining sub-bitplanes is 3.

  The number of remaining sub-bitplanes> 0 (S1714, Y), and the next coding pass is the C pass (S1715, Y). Since the number of remaining sub-bit planes ≦ 3 (S1716, Y), the C path decoding process is performed and the r value is added (S1717).

The r value addition method here is as follows. r is arbitrary 0 ≦ r <1, and r · 2 ^ (the number of bit planes−the number of decoded bit planes) in the least significant bit plane to be processed
Is added. When r is 3/8, the following values are added.
Addition value = r · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
When the decoded value is 0, no addition is performed. Here, since the decoded value is 0, no addition is performed.

  It is determined whether the number of remaining sub bit planes> 0 (S1704). Here, since the number of remaining sub-bitplanes = 2, it is determined whether the next coding pass is the S pass (S1706). Here, since it is the S path, it is determined whether or not the number of remaining sub-bitplanes ≦ 3 (S1706).

  Here, since the number of remaining sub-bitplanes ≦ 3, the S-pass decoding process is performed, and the r value is added (S1707). The number of remaining sub-bitplanes is 1. The addition method of the r value here is as described above, and is not added because the decoded value is 0.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1709). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is an R pass (S1710). Here, it is not the R path. The number of remaining sub-bitplanes is zero.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1714). Since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 0) is not satisfied, the process ends (S1719).

  The next code data “15” is processed in the same manner. Since the initial number of remaining sub-bit planes is 6 and the number of remaining sub-bit planes is not 3 (S1701, N), the C-pass decoding process is performed and the r value is not added (S1703). The number of remaining sub-bitplanes was 5.

  Since the number of remaining sub-bitplanes> 0 (S1704, Y), it is determined whether the next coding pass is the S pass (S1705).

  Here, since the S path is used (S1705, Y), it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1706). Here, since the number of remaining sub-bitplanes is not ≦ 3, the S-pass decoding process is performed and the r value is not added (S1708). The number of remaining sub-bitplanes is 4.

  Since the number of remaining sub bit planes> 0 (S1709, Y), it is determined whether the next coding pass is the R pass (S1710). Here, it is not the R path. The number of remaining sub-bitplanes was 3.

  Since the number of remaining sub-bitplanes> 0 (S1714, Y), it is determined whether the next coding pass is the C pass (S1715). Here, it is not the C path. Here, the number of remaining sub-bitplanes is 2.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1704). Here, since the number of remaining sub-bitplanes is not> 0, it is determined whether the next coding pass is the S pass (S1705). Here, it is not the S path. The number of remaining sub-bitplanes is 1.

  Since the number of remaining sub bit planes> 0 (S1709, Y), it is determined whether the next coding pass is the R pass (S1710). Here, since it is an R path, it is determined whether or not the number of remaining sub bit planes ≦ 3 (S1711). Here, since the number of remaining sub-bitplanes ≦ 3, the R-pass decoding process is performed and the r value is added (S1712). The number of remaining sub-bitplanes is zero.

The r value addition method here is as follows. r is 0 ≦ r <1, and r · 2 ^ (the number of bit planes−the number of decoded bit planes) in the least significant bit plane to be processed
Is added. When r = 3/8, the next added value is added.
Addition value = 3.8.2 ^ (5-3)
= 1
When the decoded value is 0, no addition is performed. Before adding, it is determined whether or not a bit exists in a bit plane below the least significant bit plane, and if it exists, the added value is added after subtracting the bit. Here, it is 01100, and there is no bit in the bit plane below the least significant bit plane (it is 00), so the subtraction is not performed and the addition is performed as it is. Therefore, it becomes 01101 after the addition.

Next, it is determined whether the number of remaining sub bit planes> 0 (S1714). Here, since the number of remaining sub-bitplanes = 0, the process ends (S1719).
The same processing is performed for the third and subsequent code data.

  As described above, even if the truncation point is in the coding pass (sub-bit plane) unit as in the example of FIG. 16, the necessary condition for performing the addition processing of the reconstruction value when the number of remaining sub-bit planes ≦ 3. By doing so, the reconstruction value addition process is performed only for the upper three sub-bit planes from the least significant sub-bit plane, the image quality degradation is reliably suppressed, and unnecessary processing is reduced to speed up the processing. be able to.

  An embodiment in which the setting value to be compared with the number of remaining sub-bitplanes is set to 3 for the C path and the R path and is set to 4 for the S path will be described.

  FIG. 12 is a flowchart for explaining the processing in the entropy decoding unit 3. Here, the processing content will be described with reference to the flowchart of FIG. 12, taking the code data shown in FIG. 15 as an example.

In FIG. 12, steps S1101 and S1116 correspond to a determination unit (step) for the number of remaining sub-bitplanes for the C path, and step S1106 corresponds to a determination unit (step) for the number of remaining sub-bitplanes for the S path. Step S1111 corresponds to determination means (process) for the number of remaining sub-bitplanes for the R path. However, it is clear that the number of remaining sub-bit planes is 1 or more in step 1101, and that the number of remaining sub-bit planes is checked to be 1 or more in steps S1104, S1109, and S1114. In steps S1101, S1111, and S1116, it is determined whether the number of remaining sub bitplanes is 1 or more and 3 or less. In step S1106, it is determined whether the number of remaining subbitplanes is 1 or more and 4 or less. Yes.

  FIG. 15 shows a state in which code data is divided into sub-bit planes. In this example, code data of 03 → 15 → 24... Are sequentially arranged, eight sub-bit planes are discarded from the truncation point, and the number of remaining sub-bit planes is five. For code data “03”, the C path, C path, and S path are input in this order, code data “15” is input in the order of C path and S path, and code data “24” is input in the order of C path and R path. Is done.

  In the process of the first code data “03”, it is first determined whether the number of remaining sub-bitplanes ≦ 3 (S1101). Here, since the number of remaining sub-bit planes ≦ 3 (the number of remaining sub-bit planes = 5) is not satisfied, a C-path decoding process is performed (S1103). The number of remaining sub-bitplanes is 4.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1104). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 4), it is determined whether the next coding pass is the S pass (S1105).

  Here, it is not the S path. The number of remaining sub-bitplanes was 3. It is determined whether the number of remaining sub bit planes> 0 (S1109). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 3), it is determined whether the next coding pass is an R pass (S1110).

  Here, it is not an R path. The number of remaining sub-bitplanes is 2. It is determined whether the number of remaining sub bit planes> 0 (S1114). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 2), it is determined whether the next coding pass is the C pass (S1115).

  Here, since it is the C path, it is determined whether the number of remaining sub bit planes ≦ 3 (S1116). Since the number of remaining sub bit planes ≦ 3 (the number of remaining sub bit planes = 2), the C path decoding process is performed, and the r value is added (S1117). The number of remaining sub-bitplanes is 1.

Here, the addition method of the r value is as follows. The addition value r is arbitrary 0 ≦ r <1, and when r is 3/8, r · 2 ^ (bit plane Number-number of decoded bitplanes)
= R · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
Is added. When the decoded value is 0, no addition is performed. Here, since the decoded value is 0, no addition is performed.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1104). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is the S pass (S1105).

  Here, since the S path is used, it is determined whether the number of remaining sub bit planes ≦ 4 (S1106). Since the number of remaining sub-bitplanes ≦ 4, the S-pass decoding process is performed and the r value is added (S1107). The number of remaining sub-bitplanes is zero.

Although the r value is added, the addition value r is arbitrarily 0 ≦ r <1. When r is 3/8, r · 2 ^ (number of bit planes−number of decoded bit planes) in the lowest bit plane to be processed
= R · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-3)
= 1
Is added. When the decoded value is 0, no addition is performed. Here, since the decoded value is 0, no addition is performed.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1109). Here, since the number of remaining sub-bitplanes = 0, the process ends (S1119).

  The next code data “15” is processed in the same manner. Since the initial number of remaining sub-bitplanes is 5 (S1101, N), the C path decoding process is performed (S1103). The number of remaining sub-bitplanes is 4.

  Since the number of remaining sub-bitplanes> 0 (S110, Y), it is determined whether the next coding pass is an S pass (S1105). Here, since it is the S path, it is determined whether or not the number of remaining sub bit planes ≦ 4 (S1106).

  Here, since the number of remaining sub-bitplanes ≦ 4, the S pass decoding process is performed and the r value is added (S1107). The number of remaining sub-bitplanes was 3.

Here, the r value is added, but when r is 3/8, r · 2 ^ (number of bit planes−number of decoded bit planes) is the lowest bit plane to be processed.
= R · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
Is added. When the decoded value is 0, no addition is performed. Before adding, it is determined whether or not a bit exists in a bit plane below the least significant bit plane, and if it exists, the added value is added after subtracting the bit. Here, it is 01000, and there is no bit in the bit plane below the least significant bit plane (000), so the subtraction is not performed and the addition is performed as it is. After the addition, it becomes 01011.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1109). Since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 3), it is determined whether the next coding pass is an R pass (S1110). Here, it is not an R path. The number of remaining sub-bitplanes is 2.

  It is determined whether the number of remaining sub bit planes> 0 (S1114). Since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 2), it is determined whether the next coding pass is a C pass (S1115). Here, it is not the C path. The number of remaining sub-bitplanes is 1.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1104). Since the number of remaining sub bit planes is not greater than 0 (the number of remaining sub bit planes = 1), it is determined whether the next encoding is an S pass (S1105). Here, it is not the S path. The number of remaining sub-bitplanes is zero. Since the number of remaining sub bit planes is not greater than 0 (N in S1109), the processing of the second code data is terminated (S1119).

  The same processing is performed for the third and subsequent code data.

  Here, for the C and R paths, the number of remaining sub-bit planes is 1 or more and 3 or more, which is a necessary condition for the addition processing of reconstruction values, whereas for the S path, the number of remaining sub-bit planes is 1 The reason why the above and 4 or less is a necessary condition for performing the addition process of the reconstruction value will be described. Since each code data exists in one of the S, R, and C paths, if the upper three sub-bit planes from the least significant sub-bit plane are targeted for addition processing, image quality degradation is suppressed with minimum addition processing. It should be possible. However, depending on the truncation point of the sub bit plane, the code data may not exist in any of the S, R, and C paths. This is a case where the data is truncated by the S pass as shown in FIG. In the case of the second code data “15”, there is no path in any of the upper three paths (in order of RCS) from the least significant sub-bit plane. This is because, in the case of the S path, the next path that comes out is the S path or the R path, so the next path that comes out is the R path, such as the upper fourth S path from the least significant subbit plane. If it is, the addition process is not performed. Therefore, with respect to the S path, the upper four sub-bit planes (in order of SRCS) from the least significant sub-bit plane are also subject to addition processing, so that the necessary addition processing is ensured even in the case of the example of FIG. To prevent image quality degradation.

  An embodiment for determining whether or not the addition process of the reconstruction value is necessary when the set value to be compared with the number of remaining sub-bitplanes is set to 3 for all of the S, R, and C paths and the number of remaining subbitplanes = 0 An example will be described.

  FIG. 13 is a flowchart for explaining the processing of the entropy decoding unit 3. Here, the processing content will be described with reference to the flowchart of FIG. 13 taking the code data shown in FIG. 15 as an example.

  In FIG. 13, steps S1201 and S1216 correspond to the determination means (step) for the number of remaining sub-bitplanes for the C path, and step S1206 corresponds to the determination means (step) for the number of remaining sub-bitplanes for the S path. Step S1211 corresponds to means for determining the number of remaining sub-bitplanes for the R path (step), and step S1219 is means for determining whether or not the addition process of the reconstruction value is necessary when the remaining sub-bitplane = 0. Corresponds to the step). However, it is clear that the number of remaining sub-bit planes is 1 or more in step 1201, and that the number of remaining sub-bit planes is checked to be 1 or more in steps S1204, S1209, and S1214. In steps S1201, S1206, S1211, and S1216, it is determined whether the number of remaining sub-bitplanes is 1 or more and 3 (set value) or less.

  In the first code data “03”, it is first determined whether or not the number of remaining sub-bitplanes ≦ 3 (S1201). Here, since the number of remaining sub-bit planes ≦ 3 (the number of remaining sub-bit planes = 5) is not satisfied, a C path decoding process is performed (S1203). The number of remaining sub-bitplanes is 4.

  Since the number of remaining sub-bitplanes> 0 (S1204, Y), it is determined whether the next coding pass is the S pass (S1205). Here, it is not the S path. The number of remaining sub-bitplanes was 3.

  It is determined whether the number of remaining sub bit planes> 0 (S1209). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 3), it is determined whether the next coding pass is an R pass (S1210). Here, it is not an R path. The number of remaining sub-bitplanes is 2.

  It is determined whether the number of remaining sub bit planes> 0 (S1214). Here, since the number of remaining sub-bit planes> 0 (the number of remaining sub-bit planes = 2), it is determined whether or not it is the next coding pass C pass (S1215).

  Here, since it is the C path, it is determined whether or not the number of remaining sub bit planes ≦ 3 (S1216). Since the number of remaining sub bit planes ≦ 3 (the number of remaining sub bit planes = 2), the C path decoding process is performed and the r value is added (S1217). The number of remaining sub-bitplanes is 1.

Here, the r value addition method is such that r · 2 ^ (number of bit planes−number of decoded bit planes) is added to the least significant bit plane to be processed.
Is added. When r is 3/8, the following values are actually added.
Addition value = r · 2 ^ (number of bit planes−number of decoded bit planes)
＝ 3/8 ・ 2 ^ (5-2)
= 3
When the decoded value is 0, no addition is performed. Here, since the decoded value is 0, no addition is performed.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1204). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is the S pass (S1205).

  Here, since the S path is used, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1206). Since the number of remaining sub-bitplanes ≦ 3, the S-pass decoding process is performed and the r value is added (S1207). The number of remaining sub-bitplanes is zero.

  Next, it is determined whether or not the number of remaining sub bit planes> 0 (S1209). Here, since the number of remaining sub-bitplanes is not> 0, it is determined whether or not the r value is to be added (S1219), and if it is determined to be added, the r value is added (S1220).

The determination as to whether or not to add the r value can be made, for example, based on whether or not the r value is added to the least significant bit plane. Whether or not the r value is added can be determined by whether or not there is a bit in a bit plane below the least significant bit plane. If there is a bit, it can be determined that the r value has already been added, and the process is terminated as it is (S1221). If there is no bit, it can be determined that the r value has not been added, and therefore, it is added to the bit plane of “the number of decoded bit planes (here, 3) −1” (S1220). The added value here is
Addition value = r · 2 ^ (number of bit planes− (number of decoded bit planes−1))
= 3/8 ・ 2 ^ (5- (3-1))
= 3
It becomes. When the decoded value is 0, no addition is performed. In this example, since the decoded value is 0, it is determined not to be added, and the process ends (S1221). However, the determination method in step S1219 is not limited to the above method.

  This completes the process of the first code data “03”.

  The next encoded data “15” is processed in the same manner. First, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1201). Here, since the number of remaining sub-bitplanes ≦ 3 (the number of remaining sub-bitplanes = 5) is not satisfied, C-path decoding processing is performed (S1203). The number of remaining sub-bitplanes is 4.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1204). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 4), it is determined whether the next coding pass is the S pass (S1205).

  Here, since the S path is used, it is determined whether the number of remaining sub-bitplanes ≦ 3 (S1206). Here, since the number of remaining sub-bitplanes is not ≦ 3, S-path decoding processing is performed (S1208). The number of remaining sub-bitplanes was 3.

  Next, it is determined whether or not the number of remaining sub bit planes> 0 (S1209). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 3), it is determined whether the next coding pass is an R pass (S1210). Here, it is not the R path. The number of remaining sub-bitplanes is 2.

  Next, it is determined whether the number of remaining sub bit planes> 0 (S1214). Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 2), it is determined whether the next coding pass is a C pass (S1215).

  Here, it is not the C path. The number of remaining sub-bitplanes is 1. Next, it is determined whether the number of remaining sub bit planes> 0 (S1204).

  Here, since the number of remaining sub bit planes> 0 (the number of remaining sub bit planes = 1), it is determined whether the next coding pass is the S pass (S1205). Here, it is not the S path. The number of remaining sub-bitplanes is zero.

Since the number of remaining sub-bitplanes> 0, it is determined whether or not the r value is added (S1219). The method for determining whether or not to add the r value is the same as the method described above. If r = 3/8,
Addition value = r · 2 ^ (number of bit planes− (number of decoded bit planes−1))
= 3/8 ・ 2 ^ (5- (3-1))
= 3
Will be added. The decoded value here is 01000, and since there is no bit in the bit plane below the least significant bit plane (third), it is determined to add. The added value is added to the decoded value (S1220), and the process ends (S1221). Therefore, it becomes 01011 after the addition.

  As described above, according to the present embodiment, the set value = 3 is set for all of the S, R, and C paths, but the same processing result as in the second embodiment in which the set value = 4 is set for the S path can be obtained. it can. This will be described.

  Code data exists in one of S, R, and C paths. Therefore, the addition process is performed on the upper three sub-bit planes from the least significant sub-bit plane, thereby minimizing the addition process. However, depending on the truncation point of the sub-bit plane, each encoded data may not exist in any of the S, R, and C paths. This is a case where the data is truncated by the S pass as shown in FIG. In the case of the second code data “15”, there is no coding path in any of the upper three paths (in order of RCS) from the least significant sub-bit plane. This is because, in the case of the S pass, the next encoding pass is either the S pass or the R pass, so that the next encoding passes like the upper fourth S pass from the least significant sub-bit plane. If the path is an R path, the addition process is not performed. Accordingly, in step S1219, it is determined whether or not the addition process is to be performed. If it is determined that the addition process is to be performed, by performing the addition process, it is possible to achieve suppression of image quality degradation.

  As mentioned above, although embodiment was described in detail about the decoding apparatus concerning this invention, it is clear that this is also description of the decoding method concerning this invention.

  Further, it is obvious that a general computer including a CPU, a main memory, a hard disk device, etc. can function as the decoding device of the present invention. The program for this is read into the main memory from, for example, a hard disk device or an external storage medium, and is executed by the CPU. In this case, JPEG2000 code data is read into the main memory and processed from, for example, a hard disk device or an external device, and the processing result obtained on the main memory is displayed on the display or stored in the hard disk device. Let's go. Such a program and various recording (storage) media that can be read by a computer such as a semiconductor storage element, a magnetic disk, an optical disk, and a magneto-optical disk in which the program is recorded are also included in the present invention.

It is a block diagram of the decoding apparatus of this invention. It is a figure for description of post-quantization. It is explanatory drawing of a bit plane. It is a figure explaining the scanning order at the time of decoding the coefficient on a bit plane. It is a figure explaining the coefficient of decoding object, and a neighborhood coefficient. It is a figure which shows the classification table of the context in S path | pass. It is a figure which shows the vertical and horizontal parameter | index table for determining the context of a polarity bit. It is a figure which shows the table which matched the horizontal / vertical parameter | index and the context of the polarity bit. It is a figure which shows the classification table of the context in R path | pass. It is a figure which shows the classification table of the context in C path | pass. 3 is a flowchart for explaining Example 1; 6 is a flowchart for explaining a second embodiment; 10 is a flowchart for explaining a third embodiment. It is a figure which shows the example of the code data for description of a decoding process. It is a figure which shows the example of the code data for description of a decoding process. It is a figure which shows the example of the code data for description of a decoding process.

Explanation of symbols

1 Code data input means 2 Header establishment means 3 Entropy decoding means 4 Scalar inverse quantization means 5 Inverse wavelet transform means,
6 Color conversion means 7 DC level shift means 8 Image data output means

Claims (8)

JPEG2000 decoding device,
Determining means for determining whether the number of remaining sub-bitplanes is greater than or equal to 1 and less than or equal to a set value before processing of an encoding pass in an entropy decoding process
The determination unit determines that the number of remaining sub-bitplanes is 1 or more and a setting value or less as a necessary condition for performing reconstruction value addition processing after processing of the coding pass ,
A decoding apparatus characterized in that the set value is set to 3 . JPEG2000 decoding device,
  Determining means for determining whether the number of remaining sub-bitplanes is greater than or equal to 1 and less than or equal to a set value before processing of an encoding pass in an entropy decoding process;
  The determination unit determines that the number of remaining sub-bitplanes is 1 or more and a setting value or less as a necessary condition for performing reconstruction value addition processing after processing of the coding pass,
  3. A decoding apparatus according to claim 1, wherein the setting value is set to 3 for the Magnitude Refinement path and the Cleanup path, and 4 to the Significant Propagation path.   When the number of remaining sub-bitplanes becomes 0, the apparatus further includes means for determining whether or not the addition process of the reconstruction value is necessary, and when the means determines that the addition process of the reconstruction value is necessary, The decoding apparatus according to claim 1, wherein value addition processing is performed. JPEG2000 decoding method,
  A determination step of determining whether the number of remaining sub-bitplanes is not less than 1 and not more than a set value before processing of an encoding pass in an entropy decoding process;
  The determination step determines that the number of remaining sub-bitplanes is 1 or more and less than or equal to a set value as a necessary condition for performing reconstruction value addition processing after encoding pass processing,
  A decoding method, wherein the set value is set to 3. JPEG2000 decoding method,
A determination step of determining whether the number of remaining sub-bitplanes is not less than 1 and not more than a set value before processing of an encoding pass in an entropy decoding process;
The determination step determines that the number of remaining sub-bitplanes is 1 or more and less than or equal to a set value as a necessary condition for performing reconstruction value addition processing after encoding pass processing ,
A decoding method , wherein the setting value is set to 3 for the Magnitude Refinement path and the Cleanup path, and set to 4 for the Significant Propagation path . When the number of remaining sub-bitplanes becomes 0, the method further includes a step of determining whether or not the reconstruction value addition process is necessary. 5. The decoding method according to claim 4, wherein value addition processing is performed.   The program which makes a computer function as a decoding apparatus of any one of Claims 1 thru | or 3.   A recording medium on which a program for causing a computer to function as the decoding device according to claim 1 is recorded.

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