JP3989801B2 - Image processing apparatus, image processing program, and storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus such as a computer that handles image data, an image processing program, and a storage medium.
[0002]
[Prior art]
It is inevitable that the demand for high-performance or multi-functional image compression / decompression technology that facilitates the handling of high-definition still images will become stronger in the future. Currently, JPEG (Joint Photographic Experts Group) is the most widely used image compression / decompression algorithm that facilitates handling of such high-definition still images. In recent years, the use of DWT (Discrete Wavelet Transform) is increasing as a frequency transform in place of DCT (Discrete Cosine Transform) employed in JPEG. A typical example is JPEG2000, the JPEG successor image compression / decompression method that became an international standard in 2001.
[0003]
By the way, there are various usage forms of image data compression-encoded by JPEG2000 or the like. As an example, for example, image data provided from a provider of an image file via the Internet or captured and input by a digital camera or the like is scaled (reduced or enlarged) to a desired image size on a personal computer. You may want to
[0004]
[Problems to be solved by the invention]
However, in general, when scaling the encoded image data (code data), the decoding process is temporarily performed to restore the original image data state, and then the necessary scaling is performed in the state of the image data. Processing (for example, thinning processing and interpolation processing after bitmap development) is performed, and the encoded image data is generated again by encoding the image data that has already been subjected to scaling.
[0005]
However, in such a scaling process, code data as a scaling result is obtained through a process of decoding, image scaling, and re-encoding of code data for a target image. There is a problem that it takes. In addition, since the image is restored from the code data, a working memory for handling the restored image data is required. In particular, when the code data over the entire page is returned to the image data, an extra memory is required for the work area so that a page memory is required.
[0006]
An object of the present invention is to enable high-speed processing as much as possible by using as little work memory as possible when performing image scaling on data compressed and encoded in the JPEG2000 format.
[0007]
[Means for Solving the Problems]
  The image processing apparatus according to the first aspect of the present invention includes a magnification accepting unit that accepts designation of a scaling factor, and code data that is compression-encoded as JPEG2000 format as image dataAgainstDecryptable independentlyAnd a scaling processing function for performing scaling processing of a specified scaling factor in units of code, precinct, or code block, and the scaling processing means is provided when the specified scaling factor is a reduction scaling factor. Is characterized in that the deletion process is performed by thinning out the code data in units of tiles, precincts, or code blocks based on the specified reduction scaling factor in the state of the code data.
[0008]
  Therefore, according to JPEG2000, the processing unit is a “block” (generally a rectangle) having an arbitrary size, so that the code data does not affect the coefficient value in wavelet transform / inverse transform. If it is not associated with the information of other blocks, that is, if it is a block unit that can be processed independently, it has the feature that it can be decoded independently, so it can be decoded independentlyAre tiles, precincts, or code block unitsBy applying the scaling process specified for the code data as is to the code data, basically the image size can be changed with the code data as it is without decoding the image data. Therefore, only the scaling process is required for the conventional process of decoding → image scaling → recoding, and therefore, high-speed processing is possible as much as possible by using as little work memory as possible.
[0010]
  Also,As an example of scaling processing with the code data as it is, scaling scaling can be easily performed by thinning out the code data in units of tiles, precincts, or code blocks based on the specified reduction scaling factor. .
[0011]
  Claim2The described inventionA scaling factor accepting unit that accepts designation of scaling factors, and tiles, precincts, or code blocks specified in units of code blocks that can be decoded independently of code data compressed and encoded in JPEG 2000 format as image data. It has a magnification processing function that performs magnification processing of magnification,The scaling processing means, when the specified scaling ratio is an enlargement scaling ratio,Copy the code data in tile, precinct, or code block units based on the specified magnification ratio in the code data state.Additional processing.
[0012]
  Therefore, as an example of the scaling process with the code data as it is, in the case of enlargement scaling,Based on the specified enlargement / reduction ratio, enlargement / reduction can be performed by copying the code data in units of tiles, precincts, or code blocks.Easy to do.
[0013]
  Claim 3The image processing program ofMagnification accepting function that accepts designation of variable magnification and code data compressed and encoded in JPEG2000 format as image dataAgainstDecryptable independentlyA scaling process function that performs a scaling process of a specified scaling ratio in units of tiles, precincts, or code blocks, and the scaling process function has a specified scaling ratio of a reduced scaling ratio. In this case, in the state of the code data, the deletion process is performed by thinning out the code data in units of tiles, precincts, or code blocks based on the specified reduction scaling factor.It is characterized by
[0014]
  Therefore, according to JPEG2000, the processing unit is a “block” (generally a rectangle) having an arbitrary size, so that the code data does not affect the coefficient value in wavelet transform / inverse transform. If it is not associated with the information of other blocks, that is, if it is a block unit that can be processed independently, it has the feature that it can be decoded independently, so it can be decoded independentlySpecified tiles, precincts, or code blocksBy performing the scaling process, basically the image size can be changed by scaling the code data without decoding it into the image data, and the conventional process of decoding → image scaling → re-encoding is performed. On the other hand, only the scaling process is required, and therefore high-speed processing is possible as much as possible by using as little work memory as possible.
[0016]
  Also,As an example of the scaling process with the code data as it is, as an example of the scaling process with the code data as it is, the code data in units of tiles, precincts, or code blocks based on the specified reduction scaling factor By thinning out, zooming can be easily performed.
[0017]
  Claim 4The image processing program includes a magnification reception function that accepts designation of a scaling factor, and tiles, precincts, or codes that can be independently decoded with respect to code data that has been compression-encoded as JPEG2000 format as image data. It has a scaling process function that performs a scaling process at a specified scaling ratio in block units,If the specified zoom ratio is the zoom ratio, the scaling function is based on the zoom ratio specified.TIll, or,Recinct, or,Additional processing is performed by copying the code data in units of code blocks.
[0018]
  Accordingly, as an example of the scaling process with the code data as it is, as an example of the scaling process with the code data as it is,Based on the specified enlargement / reduction ratio, enlargement / reduction can be performed by copying the code data in units of tiles, precincts, or code blocks.Easy to do.
[0019]
A computer-readable storage medium according to a seventh aspect stores the image processing program according to any one of the fourth to sixth aspects.
[0020]
  According to the present invention, the same effect as in the fourth to sixth aspects of the invention can be achieved.
[0041]
According to an eighteenth aspect of the present invention, in the image processing program according to the seventeenth aspect, the scaling process for the wavelet coefficient by the scaling processing function is performed when the designated scaling factor is a reduction scaling factor. The reduction process of the wavelet coefficient corresponding to the reduction scaling factor.
[0061]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0062]
[Outline of JPEG2000]
First, JPEG2000 will be outlined.
[0063]
FIG. 1 is a functional block diagram for explaining the basics of the JPEG2000 algorithm. As shown in FIG. 1, the JPEG2000 algorithm includes a color space transform / inverse transform unit 101, a two-dimensional wavelet transform / inverse transform unit 102, a quantization / inverse quantization unit 103, an entropy encoding / decoding unit 104, a tag process The unit 105 is configured. Hereinafter, each part will be described.
[0064]
The color space transform / inverse transform unit 101 and the two-dimensional wavelet transform / inverse transform unit 102 will be described with reference to FIGS.
[0065]
FIG. 2 is a schematic diagram illustrating an example of each component obtained by dividing an original image that is a color image. In a color image, generally, as shown in FIG. 2, each component R, G, B (111) of the original image is separated by, for example, an RGB primary color system. Each component R, G, B of the original image is further divided by a tile 112, which is a rectangular area. Each tile 112, for example, R00, R01,..., R15 / G00, G01,..., G15 / B00, B01, ..., B15 constitutes a basic unit for executing the compression / decompression process. Therefore, the compression / decompression operation is performed independently for each of the components R, G, and B (111) and for each tile 112.
[0066]
Here, at the time of encoding image data, the data of each tile 112 is input to the color space conversion / inverse conversion unit 101 shown in FIG. 1 and subjected to color space conversion, and then the two-dimensional wavelet conversion / inverse conversion unit. At 102, a two-dimensional wavelet transform (forward transform) is applied to divide the space into frequency bands.
[0067]
FIG. 3 is a schematic diagram showing subbands at each decomposition level when the number of decomposition levels is three. The two-dimensional wavelet transform / inverse transform unit 102 performs the two-dimensional wavelet transform on the tile original image (0LL) (decomposition level 0) obtained by the tile division of the original image, and displays the sub-level shown in the decomposition level 1 Separate the bands (1LL, 1HL, 1LH, 1HH). Then, the two-dimensional wavelet transform / inverse transform unit 102 continues to perform the two-dimensional wavelet transform on the low-frequency component 1LL in this hierarchy, and displays subbands (2LL, 2HL, 2LH, 2HH) indicated by the decomposition level 2 Isolate. Similarly, the two-dimensional wavelet transform / inverse transform unit 102 sequentially performs the two-dimensional wavelet transform on the low frequency component 2LL to separate the subbands (3LL, 3HL, 3LH, 3HH) indicated by the decomposition level 3. To do. In FIG. 3, the subbands to be encoded at each decomposition level are shown in gray. For example, when the number of decomposition levels is 3, the subbands shown in gray (3HL, 3LH, 3HH, 2HL, 2LH, 2HH, 1HL, 1LH, 1HH) are to be encoded, and the 3LL subband is not encoded. .
[0068]
Next, after the quantization / inverse quantization unit 103 determines the bits to be encoded in the designated encoding order, a context is generated from the bits around the target bits.
[0069]
FIG. 4 is a schematic diagram illustrating a precinct. The wavelet coefficients that have undergone the quantization process are divided into non-overlapping rectangles called “precincts” for each subband. This was introduced to use memory efficiently in implementation. As shown in FIG. 4, one precinct consists of three rectangular regions that are spatially matched. Furthermore, each precinct is divided into rectangular “code blocks” that do not overlap. This is a basic unit for entropy coding.
[0070]
FIG. 5 is a schematic diagram showing an outline of processing for decomposing the value of the two-dimensional wavelet coefficient after the two-dimensional wavelet transform into “bit plane” units and ranking the “bit plane” for each pixel or code block. . The coefficient value after wavelet transform can be quantized and encoded as it is, but in JPEG2000, in order to increase the encoding efficiency, the coefficient value is decomposed into “bit plane” units, and “ Ranking can be performed on "bit planes". FIG. 5 simply shows the procedure. In this example, the original image (32 × 32 pixels) is divided into four 16 × 16 pixel tiles, and the size of the precinct and code block at the decomposition level 1 is 8 × 8 pixels each. And 4 × 4 pixels. Precincts and code block numbers are assigned in raster order. A mirroring method is used for pixel expansion outside the tile boundary, wavelet transform is performed with a reversible (5, 3) filter, and a wavelet coefficient value of decomposition level 1 is obtained.
[0071]
FIG. 5 also shows a conceptual schematic diagram of a typical “layer” for tile 0 / precinct 3 / code block 3. The layer structure is easy to understand when the wavelet coefficient values are viewed from the horizontal direction (bit plane direction). One layer is composed of an arbitrary number of bit planes. In this example, layers 0, 1, 2, and 3 are made up of three bit planes of 1, 3, and 1, respectively. A layer including a bit plane closer to the LSB is subject to quantization first, and conversely, a layer close to the MSB remains unquantized until the end. A method of discarding from a layer close to the LSB is called truncation, and the quantization rate can be finely controlled.
[0072]
Next, the entropy encoding / decoding unit 104 will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating a code stream of encoded image data. The entropy encoding / decoding unit 104 (see FIG. 1) performs encoding on the tile 112 of each component RGB by probability estimation from the context and the target bit. In this way, encoding processing is performed in units of tiles 112 for all component RGB of the original image.
[0073]
Next, the tag processing unit 105 will be described. The tag processing unit 105 performs processing for combining all encoded data from the entropy encoding / decoding unit 104 into one code stream and adding a tag thereto. FIG. 6 simply shows the structure of the code stream. Tag information called a header is added to the head of such a code stream and the head of the partial tiles constituting each tile 112, and the encoded data of each tile 112 follows. A tag is placed again at the end of the code stream.
[0074]
On the other hand, at the time of decoding, contrary to the encoding, image data is generated from the code stream of each tile 112 of each component RGB. Such processing will be briefly described with reference to FIG. The tag processing unit 105 interprets tag information added to the code stream input from the outside, decomposes the code stream into code streams of each tile 112 of each component RGB, and code streams of each tile 112 of each component RGB Decryption processing is performed every time. At this time, the positions of the bits to be decoded are determined in the order based on the tag information in the codestream, and the quantization / inverse quantization unit 103 determines the peripheral bits of the target bit positions (decoding has already been completed). )) To generate a context. Then, the entropy encoding / decoding unit 104 performs decoding by probability estimation from the context and the code stream, generates a target bit, and writes it in the position of the target bit. Since the data decoded in this way is spatially divided for each frequency band, the two-dimensional wavelet transform / inverse transform unit 102 performs two-dimensional wavelet inverse transform on each component in the image data. Each tile 112 in RGB is restored. The restored data is converted into original color system data by the color space conversion / inverse conversion unit 101.
[0075]
Next, an example of a JPEG2000 code format will be described. FIG. 7 is a schematic diagram showing a JPEG2000 code format. The code format starts with an SOC (Start of Codestream) marker indicating the start of code data, followed by a main header describing coding parameters and quantization parameters, and further followed by actual code data. It is. The actual code data starts with an SOT (Start of Tile-part) marker and is composed of a tile header, an SOD (Start of Data) marker, and tile data (code). After the code data corresponding to the entire image, an EOC (End of Codestream) marker indicating the end of the code is added.
[0076]
FIG. 8 shows a configuration example of the main header. The main header is composed of COD, QCD essential marker segments and COC, QCC, RGN, POC, PPM, TLM, PLM, CRG, COM optional marker segments.
[0077]
FIG. 9 shows a configuration example of the tile header. FIG. 9A shows a marker segment sequence added to the head of the tile header. COD, COC, QCD, QCC, RGN, POC, PPT, PLT, COM marker segments (all options) can be used. . On the other hand, FIG. 9B is a marker segment sequence added to the head of the divided tile partial sequence when the inside of the tile is divided into a plurality of marker segments (POC, PPT, PLT, COM). Option) is available.
[0078]
Here, the markers and marker segments used in JPEG2000 will be described. The marker is composed of 2 bytes (the first byte is 0xff and the subsequent bytes are 0x01 to 0xfe). Markers and marker segments can be classified into the following six types.
[0079]
▲ 1 ▼ frame delimiting
(2) Information related to image position and size (fixed information)
(3) Coding function information (functional)
▲ 4 ▼ For error tolerance (in bit stream)
(5) Bitstream pointer
▲ 6 ▼ Auxiliary information (informational)
Among these, the markers related to the present invention are (1) and (2). Details thereof will be described below.
[0080]
First, the Delimiting marker and marker segment will be described. Delimiting markers and marker segments are essential and include SOC, SOT, SOD, and EOC. A code start marker (SOC) is added to the head of the code string. The tile start marker (SOT) is added to the head of the tile code string. The configuration of this SOT marker segment is shown in FIG. Lsot that describes the size of the marker segment, Isot that describes the tile number (number given in raster order starting from 0), Psot that describes the tile length, TPsot that describes the tile part number, and tile It consists of the contents of TNsot where the number of parts is described.
[0081]
Next, the Fixed information marker segment will be described. This is a marker that describes information about an image, and corresponds to an SIZ marker. The SIZ marker segment is added immediately after the SOC marker. The marker segment length depends on the number of components. The configuration of this SIZ marker segment is shown in FIG. Lsiz describing the size of the marker segment, Rsiz describing code string compatibility (fixed to 0, non-zero reserved), Xsiz describing the horizontal size of the reference grid, vertical size of the reference grid Ysiz in which X is described, XOsiz in which the horizontal offset position of the image from the reference grid origin is described, YOsiz in which the vertical offset position of the image from the reference grid origin is described, and XTsiz in which the horizontal size of the tile is described YTsiz that describes the vertical size of the tile, XTOsiz that describes the horizontal offset position of the tile from the reference grid origin, YTOsiz that describes the vertical offset position of the tile from the reference grid origin, and the number of components Csiz, (i) Ssiz (i), (i) in which the number of bits and the number of sign bits in the component are described XRsiz number horizontal samples in the eye of the components are described (i), constituted by the contents made YRsiz (i) the vertical number of samples are described in (i) th component.
[0082]
Here, the positional relationship between image areas and tiles in JPEG 2000 will be described. In JPEG2000, the positions of images and tiles are expressed using coordinate axes called reference grids as can be seen from the segment configuration shown in FIG. As shown in FIG. 12, the image is designated on the reference grid by the relative position (XOsiz, YOsiz) between the origin and the upper left of the image, with the upper left of the reference grid being the origin (0, 0). The actual size of the image area is obtained by (Xsiz−XOsiz) × (Ysiz−YOsiz).
[0083]
In addition, the image arranged on the reference grid is divided into rectangular regions called “tiles” and processed as described above at the time of encoding. The positional relationship between the reference grid and the tile is shown in FIG. Since a tile needs to be able to encode and decode independently, pixel reference beyond the tile boundary is not possible. The position of the tile is specified by a relative position (XTOsiz, YTOsiz) between the origin of the reference grid and the upper left of the first tile. The image offset position, tile offset position, and tile size are
0 ≦ XTOsiz ≦ XOsiz
0 ≦ YTOsiz ≦ YOsiz
XTsiz + XTOsiz> XOsiz
YTsiz + YTOsiz> YOsiz
There is a relationship.
[0084]
The total number of tiles is
Number of tiles in the horizontal direction = (Xsiz−XTOsiz) / XTsiz
Number of tiles in the vertical direction = (Ysiz−YTOsiz) / YTsiz
It is shown by the relational expression
[0085]
Further, the relationship between “image”, “tile”, “subband”, “precinct”, and “code block”, and the relationship between “packet” and “layer” are organized with reference to FIG.
[0086]
First, the order of physical size is
Image> Tile> Subband> Precinct> Code block
It is.
[0087]
The “tile” is an image divided into rectangles. When the number of divisions = 1, the image = tile. “Precinct” is a subband divided into rectangles (collected for three subbands of HL, LH, and HH. Three precincts are grouped into one, but the LL subband is divided. One precinct is a unit), and roughly represents a position in the image. The precinct can be the same size as the subband. A code block is obtained by further dividing the precinct into rectangles.
[0088]
Also, a collection of a part of the code extracted from all code blocks included in the precinct (for example, a collection of codes from the most significant bit MSB to the third bit plane of all code blocks) It is a “packet”. Here, since the “part” described above may be “empty”, the content of the packet may be “empty” in terms of code. When packets of all precincts (= all code blocks = all subbands) are collected, a part of the code of the entire image (for example, the code of the wave plane coefficients of the entire image from the MSB to the third bit plane) is obtained. This is possible, but this is a “layer”. Since the layer is roughly a part of the code of the bit plane of the entire image, the image quality increases as the number of layers to be decoded increases. A layer is a unit of image quality.
[0089]
Therefore, when all the layers are collected, all the bit plane codes of the entire image are obtained.
[0090]
[Configuration example of image processing apparatus]
In the present embodiment, by utilizing the features of JPEG2000 as much as possible, the scaling process is performed on the target image as it is without being decoded into the image data as much as possible without changing the code data. This makes it possible to change the image size.
[0091]
As an example, the image processing apparatus according to the present embodiment is realized in a computer 1 as shown in FIG. FIG. 15 is a block diagram schematically showing the hardware configuration of the computer 1. As shown in FIG. 15, the computer 1 includes a CPU (Central Processing Unit) 6 that performs information processing, a ROM (Read Only Memory) 7 that stores information, and a RAM (Random Access Memory) 8 and other primary storage devices, HDD (Hard Disk Drive) 10 for storing compressed codes downloaded from the outside via the Internet or other network 5, a CD-ROM drive for storing information, distributing information to the outside, or obtaining information from the outside 12. Communication control device 13 for transmitting information by communication with other external computers via the network 5, CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display) for displaying processing progress and results to the operator ) And the like, and an input device 14 such as a keyboard and a mouse for an operator to input commands and information to the CPU 6. The bus controller 9 operates by arbitrating data transmitted and received between these units.
[0092]
The RAM 8 has a property of storing various data in a rewritable manner, and thus functions as a work area for the CPU 6.
[0093]
In such a computer 1, when the user turns on the power, the CPU 6 activates a program called a loader in the ROM 7, reads a program for managing the hardware and software of the computer called the operating system from the HDD 10 into the RAM 8, and loads this operating system. Start. Such an operating system starts a program, reads information, or saves it in response to a user operation. As typical operating systems, Windows (registered trademark), UNIX (registered trademark), and the like are known. An operation program running on these operating systems is called an application program.
[0094]
Here, the image processing apparatus 1 stores an image processing program in the HDD 10 as an application program. In this sense, the HDD 10 functions as a storage medium that stores an image processing management program.
[0095]
In general, an operation program installed in the HDD 10 of the computer 1 is recorded on an optical information recording medium such as a CD-ROM 11 or a DVD-ROM, a magnetic medium such as an FD, or the like. Installed in the HDD 10. For this reason, portable storage media such as optical information recording media such as the CD-ROM 11 and magnetic media such as the FD can also be storage media for storing the image processing program. Furthermore, the image processing program may be taken in from the outside via, for example, the communication control device 13 and installed in the HDD 10.
[0096]
In addition, the above-mentioned image processing program includes a JPEG2000 format compression / decompression program as described above, and compresses the image data into code data by a procedure of two-dimensional wavelet transform, quantization, and encoding. It also has functions of JPEG2000 format encoding means for encoding and JPEG2000 format decoding means for decompressing compressed encoded data by the reverse procedure of decoding, inverse quantization and two-dimensional wavelet inverse transformation. is doing.
[0097]
[Overview of scaling]
In the present embodiment, in such a computer 1, as schematically shown in FIG. 16, for example, code data (original code) to be processed that has been compressed and converted by the JPEG2000 algorithm is required (for example, external). Are temporarily captured in the HDD 10 (step S1), the zoom mode designation, the zoom ratio designation, and the block unit designation for the image are accepted by the operation of the input device 14 (S2), and the processing object is processed according to these designations. The code data to be converted is subjected to a scaling process designated by a block unit designated on the work area of the RAM 8 (S3), and the code data after the scaling process is output to the object (for example, the HDD 10). Or output to the display device 15 or output to an external device through the network 5 such as the Internet. The causes (S4) that the functions of the information processing device can be realized. Note that the code data that has undergone the scaling process in step S3 is rearranged in the required code order (code stream) and output.
[0098]
Here, a magnification receiving means or a magnification receiving function is realized by step S2, and a scaling processing means or a magnification receiving function is realized by step S3. However, when configuring the image processing apparatus, the image processing apparatus may be configured as a single machine without depending on the computer 1.
[0099]
That is, according to JPEG2000, the processing unit is a “block” (generally a rectangle) of an arbitrary size, so that the code data does not affect the coefficient value in wavelet transform / inverse transform. If it is not associated with the information of other blocks, that is, if it is a block unit that can be processed independently (for example, tile unit), it can be decoded independently. By performing a scaling process of a scaling ratio designated in such a block unit (for example, tile unit) as possible (S3), the scaling process is basically performed without decoding the image data. The image size can be changed by this, and only the scaling process is required compared to the conventional process of decoding → image scaling → re-encoding, and therefore, as little work memory as possible is used. In it it is possible as much as possible high-speed processing.
[0100]
[Variation processing example 1]
Here, a specific processing example of step S3 will be described as a scaling processing example 1 with reference to FIG. First, when the scaling factor specified in step S2 is a reduction scaling factor such as 1 / M (Y in S11), N blocks having the target code data are sequentially accessed. i is initialized to 0 (S12). Subsequently, for the block unit of interest indicated by i = i + 1, M corresponding to the scaling factor 1 / M is set as the variable k for scaling processing (k = M) (S14). Then, it is determined whether or not the variable k of the block unit being accessed is 1 (S15). If k = 1 is not satisfied (N in S15), the block unit (corresponding block) of the currently accessed block is determined. The code data is deleted (that is, the corresponding block itself is deleted) (S16). Then, the variable i is incremented by 1, the variable k is decremented by 1 (S17), and it is determined again whether or not the variable k in the block unit being accessed is 1 (S15). (M-1) When the block deletion process (S16) is completed, k = 1 is satisfied (Y in S15). At this time, the process of deleting the code data of the currently accessed block (corresponding block) is performed. Without checking (the code data is left as it is), after checking whether the number of access blocks i has reached N (S13), if it has not reached N (N in S13), the above (M-1) pieces Similarly, the deletion process by thinning out the blocks is repeated to access all the blocks (Y in S13), thereby proceeding to the process in step S4.
[0101]
On the other hand, when the scaling factor designated in step S2 is an enlargement scaling factor such as M (N in S11), N blocks having the target code data are sequentially accessed. Is initialized to 0 (S21). Subsequently, M corresponding to the scaling factor 1 / M is set as the variable k for scaling processing for the target block unit indicated by i = i + 1 (k = M) (S23). Then, it is determined whether or not the variable k of the block unit being accessed is 1 (S24). If k = 1 (N of S24), the block unit (corresponding block) of the currently accessed block is determined. The code data is copied (that is, the corresponding block itself is added by copying) (S25). Then, the variable k is decremented by 1 (S26), and it is determined again whether or not the variable k for the block to be accessed is 1 (S24). (M-1) When the block addition process (S25) is completed, k = 1 (Y in S24). At this time, what is the code data of the block unit (corresponding block) currently accessed? Without checking (the code data is left as it is), it is checked whether the number of access blocks i has reached N (S22), and if N has not been reached (N in S22), the above (M-1) pieces The addition process by copying the blocks is repeated in the same manner, and all the blocks are accessed (Y in S22), whereby the process proceeds to step S4.
[0102]
In this processing example, the processing unit is shown as a processing example when the block unit is a one-dimensional array. However, the processing is basically the same when the block unit is a two-dimensional array. Processing such as deletion and addition may be performed in both directions. .
[0103]
As a specific example, the block unit is a tile unit (including header information describing the contents), and the scaling factor is specified as a reduction scaling factor of 1 / M = 1/3. A processing example is shown in FIG. That is, if the code data before scaling is composed of 36 tiles indicated by TA01 to TA36, tiles TA01, TA04, TA19 are deleted by thinning out two tiles vertically and horizontally in the tile access operation. , TA22, and only the code data of four tiles remains, and the state after scaling that is reduced to 1/3 is obtained in the code state.
[0104]
Also, as another specific example, similarly, when the block unit is a tile unit (including header information describing the contents) and the scaling factor is designated as an enlargement scaling factor of M = 3 An example of processing is shown in FIG. That is, if the code data before scaling is composed of four tiles indicated by TA01 to TA04, the code of 36 tiles can be obtained by adding two tiles by copying vertically and horizontally in the tile access operation. The state after scaling that has been enlarged by three times with data is obtained in the code state.
[0105]
In these processing examples, the block unit that can be processed has been described as an example of a tile unit having header information. However, according to JPEG2000, a code block (described above) can be used as a block unit that can be processed independently. Code Block), a set of code blocks (precinct), and instead of processing in units of tiles, the scaling process (deletion, addition processing) described above is performed in units of precincts or code blocks. Also good. In this way, the image size can be changed by deleting or adding a block unit. At this time, the block unit to be processed is preferably a rectangular small area.
[0106]
[Zooming processing example 2]
In this processing example, the scaling process is performed using wavelet coefficients instead of the scaling process with the code data as it is. As described above, the scaling process is performed in units of blocks that can be processed independently. However, if the block size is large, the scaling process by deleting or adding the blocks as described above will improve the image quality. Since there may be a case where a problem may occur, this is an example in which the wavelet coefficients are restored (not restored up to the image data) and the scaling process is performed in units of the wavelet coefficients.
[0107]
FIG. 19 shows a schematic flowchart of a scaling process example corresponding to step S3 in this processing example. Schematically, the target code data is decoded by the decoding means in the JPEG2000 format, thereby restoring the wavelet coefficients in block units (S31). Then, the wavelet coefficient included in each restored block unit is subjected to a scaling process for the scaling factor specified in the wavelet coefficient unit (S32), and the wavelet coefficient after the scaling process is encoded by the encoding means in the JPEG2000 format. Data is re-encoded (S33), and the process proceeds to step S4.
[0108]
In this case, various forms can be adopted as the scaling process in units of wavelet coefficients. For example, when the specified scaling factor is a reduction scaling factor, the wavelet coefficient corresponding to the reduction scaling factor is reduced in units of wavelet coefficients. For example, the block unit corresponding to the scaling scaling factor is performed. This may be a process of changing (increasing / decreasing) the value of the wavelet coefficient itself, or as another example, a process of changing (deleting or adding) the number of wavelet coefficients included in a block unit. The same applies when the specified scaling factor is an enlargement scaling factor. Wavelet coefficients corresponding to the enlargement scaling factor are enlarged in units of wavelet coefficients. As an example, a wavelet corresponding to the enlargement scaling factor is used. It may be a process of changing (increasing or decreasing) the coefficient value itself, and as another example, a process of changing (deleting or adding) the number of wavelet coefficients included in a block unit.
[0109]
As a specific example, FIG. 21 shows a processing example when the block unit is a tile unit and the scaling factor is specified as a scaling factor of 1 / M = 1/2. That is, in this example, the code data before scaling is composed of 16 tiles indicated by TA01 to TA16, and the scale data is reduced to 4 tiles indicated by TB01 to TB04 as code data after scaling. is there. In this case, for example, the wavelet coefficient corresponding to the code data (Code) is obtained for the tiles TA03, TA04, TA07, and TA08 by the processing in step S31. Then, the scaling process of 1/2 scaling factor specified for the wavelet coefficients (Wavelet coefficients) for these four tiles is performed with the wavelet coefficients as a result of the process of step S32, and a new one for a new tile TB02 Wavelet coefficients are obtained. Although not particularly illustrated, the same applies to the set of tiles TA01, TA02, TA05, and TA06, the set of tiles TA09, TA10, TA13, and TA14, and the set of tiles TA11, TA12, TA15, and TA16. Then, the obtained wavelet coefficients (Wavelet coefficients) for the four new tiles TB01 to TB04 are re-encoded into code data (Code) by the process of step S33 and converted into a code stream by the tag process. As shown in the lowermost column, code data reduced in size by 1/2 in the vertical and horizontal directions is obtained.
[0110]
As described above, for example, as a specific scaling process, the selection of the decomposition level is performed by using the scaling process using the data restored to the wavelet coefficients without performing the scaling process with the code data as it is. The size can be changed substantially by changing the resolution by using the wavelet coefficient characteristics, and more flexible scaling processing is possible. Therefore, high-speed processing can be performed with less work memory than in the past.
[0111]
【The invention's effect】
  BookAccording to the invention, since the processing unit of JPEG 2000 is a “block” of an arbitrary size (generally a rectangle), the code data does not affect the coefficient value in wavelet transform / inverse transform. If it is not associated with other block information, that is, if it is a tile, precinct, or code block unit that can be decoded independently, the feature that it can be decoded independently is maximized. Code data that is basically decoded without being decoded into image data by applying a scaling process of a specified scaling ratio in units of tiles, precincts, or code blocks that can be independently decoded. The image size can be changed by scaling processing as it is, and the processing of scaling processing is compared to the conventional process of decoding → image scaling → re-encoding. It can to dispense with, thus, it is possible to perform the process as much as possible high speed use of the working memory as small as possible.
[0112]
  Also bookAccording to the inventionThe markAs an example of the scaling process without changing the data, based on the specified reduction scaling factorIn the code data state,By thinning out the code data in units of tiles, precincts, or code blocks, reduction scaling can be easily performed.
[0113]
  Furthermore, according to the present invention,As an example of the scaling process with the code data as it is, based on the specified magnification ratioIn the code data state,By copying the code data in units of tiles, precincts, or code blocks, enlargement / reduction can be easily performed.
[0114]
  According to the computer-readable storage medium of the seventh aspect of the invention, the same effects as the inventions of the fourth to sixth aspects can be obtained.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a system that implements a basic algorithm of the JPEG2000 system that is a premise of an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a divided rectangular area of each component of the original image.
FIG. 3 is an explanatory diagram showing subbands at each decomposition level when the number of decomposition levels is 3. FIG.
FIG. 4 is an explanatory diagram showing a precinct.
FIG. 5 is an explanatory diagram showing an example of a procedure for ranking bit planes; It is.
FIG. 6 is a schematic diagram illustrating a code stream of encoded image data.
FIG. 7 is a schematic diagram showing a code format of JPEG2000.
FIG. 8 is a configuration diagram of the main header.
FIG. 9 is a configuration diagram of a tile header.
FIG. 10 is a configuration diagram of an SOT marker segment.
FIG. 11 is a configuration diagram of a SIZ marker segment.
FIG. 12 is an explanatory diagram showing the positional relationship of images.
FIG. 13 is an explanatory diagram showing a positional relationship between a reference grid and tiles.
FIG. 14 is an explanatory diagram illustrating a relationship between an image, a tile, a subband, a precinct, and a code block.
FIG. 15 is a block diagram illustrating a computer configuration example for realizing the image processing apparatus according to the present embodiment;
FIG. 16 is a schematic flowchart showing the scaling process.
FIG. 17 is a schematic flowchart showing a process of scaling process example 1;
FIG. 18 is a schematic diagram showing a specific example of the reduction process.
FIG. 19 is a schematic diagram showing an example of a specific enlargement process.
FIG. 20 is a schematic flowchart showing processing of scaling processing example 2;
FIG. 21 is a schematic diagram showing a specific example of the reduction process.
[Explanation of symbols]
S2 Magnification acceptance means, magnification acceptance function
S3 Scaling processing means, scaling processing function

Claims (5)

A magnification acceptance means for accepting designation of a variable magnification;
Scaling processing means for performing scaling processing of a scaling factor designated in units of tiles, precincts, or code blocks that can be independently decoded with respect to code data compressed and encoded in the JPEG 2000 format as image data And
When the designated scaling factor is a reduction scaling factor, the scaling processing means is in the state of the code data, based on the specified reduction scaling factor, in units of tiles, precincts, or code blocks. An image processing apparatus that performs a deletion process by thinning out code data .   A magnification acceptance means for accepting designation of a variable magnification;
  Scaling processing means for performing scaling processing of a scaling factor designated in units of tiles, precincts, or code blocks that can be independently decoded with respect to code data compressed and encoded in the JPEG 2000 format as image data And
If the specified scaling factor is an enlargement scaling factor, the scaling processing means is in the state of the code data, based on the specified scaling scaling factor, in tiles, precincts, or code block units. An image processing apparatus that performs additional processing by copying code data. Installed in a computer included in the image processing apparatus,
Magnification reception function that accepts designation of variable magnification,
Scaling processing that performs scaling processing at a specified scaling ratio in units of tiles, precincts, or code blocks that can be decoded independently of code data compressed and encoded in the JPEG2000 format as image data With functions,
When the specified scaling factor is a reduction scaling factor, the scaling processing function is configured to code the tile, the precinct, or the code block based on the specified reduction scaling factor in the code data state. An image processing program for performing deletion processing by thinning out code data in units . Installed in a computer provided in the image processing apparatus,
  Magnification reception function that accepts designation of variable magnification,
  Scaling processing that performs scaling processing at a specified scaling ratio in units of tiles, precincts, or code blocks that can be decoded independently of code data compressed and encoded in the JPEG2000 format as image data With functions,
When the specified scaling factor is an enlargement scaling factor, the scaling processing manual function is based on the specified enlargement scaling factor in the code data state, the tile, the precinct, or the code. An image processing program for performing additional processing by copying code data in block units. A computer-readable storage medium storing the image processing program according to claim 3 or 4.

Images