JP4520499B2 - Image processing apparatus, image processing program, and storage medium - Google Patents

Description

  The present invention relates to various image processing apparatuses such as a personal computer, an image processing program, and a storage medium.

  The development of network technology in recent years has been remarkable, and the Internet has become popular. Under such circumstances, the server serving as a content distribution source handles various images when creating content. That is, in addition to a natural image such as a photograph taken by a digital camera or the like or input from a scanner or the like, for example, a computer graphics image (CG image) artificially created by a computer or a normal document Such as binary images, character graphic images (limited color images) expressed in palette colors according to the palette color method, and single-color images of only one color. These various images are combined in one content document. There are many cases in which editing is included. Here, for example, in the case of a CG image, compared to a natural image such as a photograph, while the same color pixels are continuous, the color between adjacent pixels may be extremely different. . Further, regarding a color image, for example, there is a characteristic that the configuration of image data is completely different between an 8-bit natural image of RGB colors input from a digital camera or the like and a character graphic image using a palette color.

  On the other hand, servers that handle this type of image data should be compressed and stored in order to save memory capacity or to reduce the data capacity for distribution and transfer at high speed. Is essential.

  With regard to such image compression encoding processing, conventionally, for example, encoding by switching between binary encoding and multi-level encoding is known. As an example, a proposal example comprising a plurality of compression means, partially compressing an image by the first compression method, discriminating the type of image from the compression rate, and selecting the final compression method (For example, refer to Patent Document 1).

In addition, an image compression encoding technique based on the JPEG2000 algorithm has attracted attention as a high-definition image compression / decompression technique that can restore a high-quality image at a high compression rate.
Japanese Patent No. 2814970

  However, according to the prior art disclosed in Patent Document 1 and the like, compression encoding processing according to the type of image is binary or multi-valued is possible, but originally different types of compression encoding processing are performed. An encoder must be prepared, which is not efficient, and complicates the configuration of the entire image processing apparatus and increases costs. Moreover, it will be limited to the kind of binary or multi-value.

  In addition, if the JPEG2000 algorithm is used, some high-efficiency encoding processes are included. Basically, high-efficiency and high-compression compression encoding is possible. Depending on the characteristics of the image, it is not always effective, and there are cases where the processing becomes wasteful and the coding efficiency is worsened.

  An object of the present invention is to use image compression coding technology based on the JPEG2000 algorithm to compress and encode content images and the like, and basically process image data having various characteristics with a single encoder at high efficiency. It is possible to avoid the inconvenience of the JPEG2000 algorithm at that time.

  An image processing apparatus according to a first aspect of the present invention includes a compression encoding unit that compresses and encodes image data in accordance with the JPEG2000 algorithm, and a process in the compression encoding unit for image data to be compressed and encoded. A plurality of code acquisition means for selecting and performing a plurality of types of compression encoding processes having different processing contents on the image data by the compression encoding means; and a plurality of codes acquired by the plurality of code acquisition means Selecting means for selecting, as an actual code, one having processing efficiency with high encoding efficiency.

  Therefore, by using compression encoding means that basically performs compression encoding according to the JPEG2000 algorithm, compression encoding processing of image data having various characteristics can be handled with a single encoder, and the configuration is simple and highly efficient. In addition, the processing by the compression encoding means is selected and a plurality of types of compression encoding processing having different processing contents are performed, and as a result, the one having the processing contents with the highest encoding efficiency is selected as the actual code. Thus, even if the characteristics of the image data are not actually discriminated, as a result, by selecting the most efficient encoding data, it is possible to eliminate the waste due to the processing contents and avoid the disadvantages of the JPEG2000 algorithm. It becomes possible.

  According to a second aspect of the present invention, there is provided an image processing apparatus for compressing and encoding image data in accordance with the JPEG2000 algorithm, and for discarding the processing in the compression encoding means for the image data to be subjected to compression encoding. A plurality of code acquisition means for selecting and performing a plurality of types of compression encoding processing with different processing contents on the image data by the compression encoding means; and for each of different processing contents acquired by the plurality of code acquisition means A result providing unit that provides the user with the encoding efficiency, image quality, and other information regarding a plurality of codes, and a selection unit that selects, as an actual code, one according to the processing content specified by the user.

  Therefore, by using compression encoding means that basically performs compression encoding according to the JPEG2000 algorithm, compression encoding processing of image data having various characteristics can be handled with a single encoder, and the configuration is simple and highly efficient. For example, by selecting the processing by the compression encoding means and performing a plurality of types of compression encoding processing with different processing contents, and providing the result to the user and specifying the desired processing contents, for example, If there is no significant difference in encoding efficiency, it is possible to select one with good image quality, so that it does not actually determine the characteristics of the image data. By selecting one, it is possible to avoid the disadvantages of the JPEG2000 algorithm.

  According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, the compression encoding means includes a DC level conversion process, a color conversion process, a two-dimensional wavelet transform process, a quantization process, a coefficient modeling process, Image data is compression-encoded using procedures such as arithmetic encoding processing and code order control processing. Among these processing, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are selected. The target of.

  Therefore, in the JPEG2000 algorithm, DCPEG level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing prior to entropy coding processing called coefficient modeling processing are selected as targets for selection, thereby making JPEG2000 different. It is possible to perform high-speed processing with high coding efficiency without losing the characteristics of the algorithm and omitting wasteful processing according to the characteristics of actual image data.

  According to a fourth aspect of the present invention, there is provided an image processing program installed in a computer, wherein the computer is configured to compress and encode image data according to the JPEG2000 algorithm, and to the image data to be compressed and encoded. A plurality of code acquisition functions for selecting a process in the compression encoding function and performing a plurality of types of compression encoding processes having different processing contents on the image data by the compression encoding function, and the plurality of code acquisition functions And a selection function for selecting, as an actual code, one having a process content with the highest coding efficiency from among the plurality of codes acquired by the above-described method.

  Therefore, by using a compression coding function that basically performs compression coding according to the JPEG2000 algorithm, compression coding processing of image data having various characteristics can be handled with a single encoder, and the configuration is simple and highly efficient. In addition, the processing by the compression coding function is selected and a plurality of types of compression coding processing having different processing contents are performed, and as a result, the processing code having the highest coding efficiency is selected as the actual code. Thus, even if the characteristics of the image data are not actually discriminated, as a result, by selecting the most efficient encoding data, it is possible to eliminate the waste due to the processing contents and avoid the disadvantages of the JPEG2000 algorithm. It becomes possible.

  According to a fifth aspect of the present invention, there is provided an image processing program installed in a computer, wherein the computer is configured to compress and encode image data in accordance with the JPEG2000 algorithm, and to compress and encode image data. A plurality of code acquisition functions for selecting a process in the compression encoding function and performing a plurality of types of compression encoding processes having different processing contents on the image data by the compression encoding function, and the plurality of code acquisition functions A result providing function for providing the user with the encoding efficiency, image quality, and other information regarding a plurality of codes for each different processing content acquired by the method, and selecting the actual code according to the processing content specified by the user And a selection function.

  Therefore, by using a compression coding function that basically performs compression coding according to the JPEG2000 algorithm, compression coding processing of image data having various characteristics can be handled with a single encoder, and the configuration is simple and highly efficient. For example, by selecting the processing by the compression encoding function and performing a plurality of types of compression encoding processing with different processing contents and providing the result to the user and specifying the desired processing contents, for example, If there is no significant difference in encoding efficiency, it is possible to select one with good image quality, so that it does not actually determine the characteristics of the image data. By selecting one, it is possible to avoid the disadvantages of the JPEG2000 algorithm.

  A computer-readable storage medium according to a sixth aspect stores the image processing program according to the fourth or fifth aspect.

  Therefore, the same effect as that of the invention according to claim 4 or 5 is exhibited.

  According to the image processing apparatus of the present invention, the compression encoding means for performing compression encoding according to the JPEG2000 algorithm is basically used, so that the compression encoding processing of image data having various characteristics can be handled by a single encoder. In addition to being simple and highly efficient, the processing by this compression encoding means is selected and a plurality of types of compression encoding processing with different processing contents are performed. As a result, the processing contents with the highest encoding efficiency are obtained. Since it is selected as an actual code, it is possible to eliminate unnecessary processing contents by selecting the most efficient coding result without actually determining the characteristics of the image data. And the inconvenience of the JPEG2000 algorithm can be avoided.

  An embodiment of the present invention will be described with reference to the drawings.

[Overview of JPEG2000]
This embodiment uses the JPEG2000 algorithm. First, JPEG2000 will be outlined.

  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, and tag processing. The unit 105 is configured. Hereinafter, each part will be described.

  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.

  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.

  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.

  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. .

  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.

  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.

  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 values after the wavelet transform can be quantized and encoded as they are, but in JPEG2000, in order to increase the encoding efficiency, the coefficient values are 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.

  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.

  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.

  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 the 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.

  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.

  Next, an example of a JPEG 2000 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 a SOT (Start of Tile-part) marker, and includes a tile header, an SOD (Start of Data) marker, and tile data (code). After the code data corresponding to the whole image, an EOC (End of Codestream) marker indicating the end of the code is added.

[Server client system]
Next, a configuration example of a server computer that is an image processing apparatus according to the present embodiment will be described. The server computer according to the present embodiment performs image processing by being controlled by an image processing program that is installed in the computer or interpreted and executed. In this embodiment, a storage medium for storing such an image processing program is also introduced.

  FIG. 8 is a schematic diagram showing an example of system construction in the present embodiment. In the image data processing system of this embodiment, a server client system 1 is assumed in which a plurality of client computers 4 are connected to a server computer 2 via a network 3 such as a LAN (Local Area Network). The server client system 1 has an environment in which an image input device 5 such as a scanner or a digital camera and an image output device 6 such as a printer can be shared on the network 3. In addition, an MFP 7 called a multifunction peripheral may be connected on the network 3, and an environment may be constructed so that the MFP 7 functions as the image input device 5 or the image output device 6.

  Such a server client system 1 is constructed so as to be capable of data communication with another server client system 1 via, for example, an intranet 8 and constructed so as to be capable of data communication with an external environment via an Internet communication network 9.

  The server computer 2 of the present embodiment is a content distribution source on the Internet communication network 9, for example. Various content image data is created in the server computer 2, and is compressed and encoded in accordance with the JPEG2000 algorithm described above. It is assumed that the data is transferred to various delivery destinations through the communication network 9 or the like.

  FIG. 9 is a module configuration diagram of the server computer 2 as the image processing apparatus according to the present embodiment. The server computer 2 stores a CPU (Central Processing Unit) 11 that performs information processing, a ROM (Read Only Memory) 12 that stores information, a RAM (Random Access Memory) 13, and other primary storage devices 14, and stores compression codes. A secondary storage device 16 such as an HDD (Hard Disk Drive) 15, a removable disk device 17 such as a CD-ROM drive for storing information, distributing information to the outside, and obtaining information from the outside, and a network 3 A network interface 18 for transmitting information to other external computers through communication, a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Dis) for displaying processing progress and results to the operator. lay) and the like, a keyboard 20 for an operator to input commands and information to the CPU 11, a pointing device 21 such as a mouse, and the like. The controller 22 operates by arbitrating.

  In such a server computer 2, when the user turns on the power, the CPU 11 activates a program called a loader in the ROM 12, reads a program for managing the hardware and software of the computer called the operating system from the HDD 15 into the RAM 13, and this operating system Start up. 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.

  Here, the server computer 2 stores an image processing program in the HDD 15 as an application program. In this sense, the HDD 15 functions as a storage medium that stores the image processing program.

  In general, an operation program installed in the secondary storage device 16 such as the HDD 15 of the server computer 2 is recorded on an optical information recording medium such as a CD-ROM or DVD-ROM, a magnetic medium such as an FD, or the like. The recorded operation program is installed in the secondary storage device 16 such as the HDD 15. For this reason, portable storage media such as optical information recording media such as CD-ROM and magnetic media such as FD can also be storage media for storing image processing programs. Furthermore, the image processing program may be imported from the outside via, for example, the network interface 18 and installed in the secondary storage device 16 such as the HDD 15.

  In the server computer 2, when an image processing program operating on the operating system is started, the CPU 11 executes various arithmetic processes according to the image processing program and controls each unit intensively.

  In addition, the server computer 2 of the present embodiment includes each functional block of the JPEG2000 algorithm described with reference to FIG. 1, and compresses and encodes image data using the JPEG2000 algorithm as described above. That is, the functions of the compression encoding means and the decoding means as shown in FIG. 1 are executed by the processing performed by the CPU 11 based on the program stored in the HDD 15 or the like even if the functions are executed by the hardware. May be. As a result, for example, when creating and saving content images, digital image data input from various image input devices 5, 7, 4 and the like is compressed and encoded by the JPEG2000 algorithm, and a code stream of each image is generated. To do. That is, the image is basically divided into one or a plurality of rectangular areas (tiles), and pixel values are discretely wavelet transformed for each rectangular area and hierarchically compressed and encoded.

[Image compression encoding processing]
When the compression encoding means based on the JPEG2000 algorithm shown in FIG. 1 is rewritten, it can be shown as in FIG. In other words, the DC level conversion unit 101a, the color conversion unit 101b, the wavelet conversion unit 102a, the quantization unit 103a, the coefficient modeling unit 104a, the arithmetic encoding unit 104b, and the code order control unit 105a are arranged in the order of processing to perform compression encoding 106 is configured. Here, the DC level conversion unit 101a and the color conversion unit 101b belong to the color space conversion / inverse conversion unit 101, and the DC level conversion unit 101a has a positive number of input image signals such as RGB signal values. In some cases, a level conversion process is performed to subtract 1/2 of the dynamic range of the signal from each signal value using a predetermined conversion formula, and the color conversion unit 101b converts the RGB image into a luminance-color-difference YCbCr image. Performs processing to increase color image compression efficiency. The wavelet transform unit 102a belongs to the two-dimensional wavelet transform / inverse transform unit 102, and performs the conversion process to the wavelet coefficient as described above. The quantization unit 103a belongs to the quantization / inverse quantization unit 103, and performs a process of reducing the dynamic range of the wavelet coefficient in order to perform efficient compression. As an example of this quantization processing, there is a post-quantization method that uses the fact that entropy coding described later is a bit plane, and performs quantization by truncating the lower bit plane of the completed code string.

  The coefficient modeling unit 104a and the arithmetic coding unit 104b belong to the entropy coding / decoding unit 104 that performs block-based bit-plane coding. Among them, the coefficient modeling unit 104a creates a bit model for binary arithmetic encoding from the multi-value wavelet coefficients to be encoded, and the encoding method is determined by this processing. As a coding method in the arithmetic coding unit 104b, a method called MQ-Coder, which is a new binary image coding method, is used. The code order control unit 105 a is included in the tag processing unit 105.

  In addition to the compression encoding means 106 according to the JPEG2000 algorithm as described above, in the present embodiment, image characteristics for determining the characteristics of document image data input as a processing target and outputting a determination signal corresponding to the characteristics An image characteristic discriminating unit 121 as a discriminating unit, and a process of selecting the processing in the compression encoding unit 106 in accordance with the discrimination signal output from the image characteristic discriminating unit 121 and making the content of the compression encoding process different A selector 122 as content switching means is provided.

  The image characteristic discriminating unit 121 discriminates the characteristics of the image data to be compression-encoded by the compression-encoding unit 106. Specifically, the image characteristic discriminating unit 121 is a natural image, a computer graphics image (CG). Image), palette image (limited color image), single color image, or binary image, and a determination signal corresponding to the determination result is output to the selector 122. As a method for discriminating the characteristics of such an image, a well-known technique may be used. Therefore, for example, in the case of a binary image such as a text image, a white background and a black color are used. In most cases, it shows a single gradation value that is the maximum gradation value or the minimum gradation value, so a histogram of gradation values (levels) in the image data is created, and the results are biased In some cases, it is possible to use a technique for discriminating a binary image and, if there is no bias, a technology for discriminating a natural image (see, for example, Japanese Patent Laid-Open No. 2000-222564). In addition, a CG image that is a typical artificial image has a strong correlation with surrounding pixels when attention is paid to one pixel, and conversely, a natural image has a weak correlation with surrounding pixels. A technique for discriminating a CG image when the correlation with surrounding pixels is strong, and a technique for discriminating a natural image when the correlation with surrounding pixels is weak can be used (see, for example, JP-A-2002-194417). . Furthermore, paying attention to the number of colors of the image, a technique is used in which a single image is determined when the number of colors is one, a palette image is determined when the number of colors is small, and a natural image is determined otherwise. (See, for example, JP-A-11-88700).

  The selector 122 selects the processing in the compression encoding means 106 in accordance with the determination signal output from the image characteristic determination unit 121 and changes the processing content of the compression encoding. In the algorithm, the processing of the DC level conversion unit 101a, the processing of the color conversion unit 101b, the processing of the two-dimensional wavelet conversion unit 102a, and the processing of the quantization unit 103a before entropy coding processing called coefficient modeling processing are sorted out according to the discrimination signal. As a selection target, the processing contents of compression encoding are varied according to the characteristics of the image data.

  Here, for example, an encoding style table 123 as shown in FIG. 11 is provided in the ROM 12 in which the selection regarding the processing in the compression encoding means 106 is defined for each characteristic of the image data. The processing is selected with reference to the style table 123, and the processing contents of the compression encoding for the image data are made different. Specifically, as shown in the encoding style table 123, in the case of a natural image, all the DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are selected (indicated by a circle). In the case of a palette image or binary image, all of the DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are omitted (indicated by x), and a computer graphics image ( In the case of a CG image, only the quantization process is arbitrarily selected (indicated by a triangle; it may be set to any one by the initial setting). In the case of a monochromatic image, a DC level conversion process, a two-dimensional wavelet It is defined that a conversion process and a quantization process are selected.

  The functions of the image characteristic determination unit 121 and the selector 122 may also be executed by processing performed by the CPU 11 based on a program stored in the HDD 15 or the like.

  In general, when considering the feature of compression coding by the JPEG2000 algorithm, there is bit plane coding as described above, and as an image, an image having a characteristic that can be originally represented by 1-bit information, for example, Even for a binary image or a palette image, it is necessary to encode a plurality of bit planes, and as a result, it has the same meaning as performing unnecessary encoding, resulting in poor encoding efficiency and processing speed. There is also a bug that will slow down. The same applies to computer graphics images (CG images). In addition, since a single color image has only a single color, it does not make much sense to perform the process of converting the color space by the color conversion unit 101b from the beginning. In this regard, according to the basic configuration of the present embodiment, when compressing and encoding document image data, a natural image such as a photograph is all processed by the compression encoding means 106. For images having characteristics, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are not appropriately performed according to the characteristics, and subsequent entropy encoding processing (coefficient modeling processing) is performed. By doing so, useless processing can be omitted, and processing speed and encoding efficiency can be improved.

  FIG. 12 is a flowchart showing an outline of such image compression encoding processing. First, input of image data to be subjected to compression encoding is received (step S1). Here, the characteristic of the image data is discriminated by the image characteristic discriminating unit 121, and a discrimination signal suitable for the characteristic is output to the selector 122 (S2). The selector 122 refers to the coding style table 123 and selects the processing in the compression coding means 106 so that the compression coding processing suitable for the discrimination signal is achieved (S3). When the encoding style by the compression encoding means 106 is determined by this process, the image data is compression encoded by the compression encoding means 106 according to the encoding style (S4), thereby obtaining the compression encoded code data. It is done. The code data is appropriately stored in the HDD 15 or the like and used for use as a content image.

[Specific processing example]
Processing for processing document image data of a simple document 134 in which a character image 131 such as text, a CG image 132, and a natural image 133 such as a photograph are mixed as shown in FIG. Several examples will be described.

First, as a first example, in the simplest case, for example, a character image with respect to the entire document image data according to the ratio of each area of the character image 131, the CG image 132, and the natural image 133 in the document image data. The selector 122 can be configured to switch the selection of processing contents so that any one coding style mode for CG, CG image, and natural image is applied. The compression encoding processing method in this case is a tile method in which a tile is divided into a plurality of tiles and encoded in units of tiles, but is a raster method in which each raster line is divided and encoded in units of raster lines. Also good.
In this case, as shown in FIG. 14, the compression coding means 106 describes coding mode information indicating which coding style mode is applied in the main header area of the compression coded code data. In this case, when decoding the code data, it is possible to decode without error by referring to the encoding mode information. The example shown in FIG. 14 is a tile encoding method (see FIG. 13B). FIG. 14A applies the binary mode to compress and encode the entire document image data. Shows an example in which the entire document image data is compression-encoded by applying the CG mode.

  Next, as a second more practical example, the processing mode may be dynamically switched in a certain small area unit = tile unit. For example, document image data as shown in FIG. 13A is divided into a plurality of tiles A1, A2,..., F3 and F4 as shown in FIG. You may make it switch what mode encoding style is used.

  FIG. 15 shows an example of a code string that has been compression-encoded by the compression-encoding means 106 by this method, and the mode applied to the main header area is any encoding style mode as shown in the example of the drawing. If such coding mode information is described for each tile, the decoding can be performed without error by referring to the coding mode information when decoding the code data.

  However, not only the method described in the main header area, but what is the coding style mode individually applied to the code data (tile header part) of each compression-coded tile as shown in FIG. Such encoding mode information may be described. Even with this method, when decoding the code data, it is possible to decode without error by referring to the encoding mode information.

  As a third more practical example, the processing mode may be dynamically switched in a certain small area unit = raster line unit. For example, document image data as shown in FIG. 13A is divided into a plurality of raster lines y0, y1,... As shown in FIG. You may make it switch what mode a style uses.

  FIG. 17 shows an example of a code string that has been compression-encoded by the compression-encoding means 106 using this method. As shown in the example of FIG. 17, the code indicating what the encoding style mode is applied to the main header area. If the encoding mode information is described by a raster line whose mode changes, the encoding mode information can be decoded without error by referring to the encoding mode information when decoding the code data. In the illustrated example, processing in the binary mode is performed from raster line 0, the raster line y1 is switched to the CG mode, the raster line y3 is switched to the binary mode, the raster line y11 is switched to the natural mode, and the raster line is It is indicated that the mode is switched to the binary mode at y13.

  However, not limited to the method described in the main header area, as shown in FIG. 18, information on raster lines in which the coding style mode to be individually applied is switched in the compression-coded code data. It may be described as information. Even with this method, when decoding the code data, it is possible to decode without error by referring to the encoding mode information.

  In the present embodiment, the server computer 2 has been described as having a configuration including the image characteristic determination unit 121. However, a configuration in which the server computer 2 does not include the image characteristic determination unit 121 and is obtained as an external signal may be used. That is, it may be configured such that a determination signal related to the image characteristics is input from the outside, but the server computer 2 itself includes the image characteristic determination unit 121, so that an appropriate image compression coding process can be performed by itself. It becomes possible.

[Another embodiment]
In the above-described one embodiment, after the characteristics of the image are determined, the processing in the compression encoding means 106 is selected and the encoding style is changed according to the determination result. In one embodiment, when image data is input, four types of encoding styles (pallet image and the like) are used without determining the characteristics of the image, for example, as in the case of the encoding style table 123 shown in FIG. The compression encoding process using the same encoding style as the binary image) is executed in parallel or sequentially (multiple code acquisition means or multiple code acquisition function), and the encoding efficiency of the codes obtained by each encoding style ( Compression ratio), and the coding efficiency is the best
The data based on the encoding style may be selected as the code data actually compressed and encoded by the compression encoding means 106 (selection means or selection function).

  According to such a processing mode, a plurality of types of compression encoding processes with different encoding styles are performed by selecting processing by the compression encoding means 106, and as a result, the encoding style having the highest encoding efficiency is used. As a result, it is possible to eliminate unnecessary coding styles by selecting the most efficient coding data without actually determining the characteristics of the image data. And the inconvenience of the JPEG2000 algorithm can be avoided.

  In the case of such a processing form, without automatically selecting a coding style from the calculated coding efficiency, information that is used as a judgment material such as the coding efficiency of each coding style and the image quality of a decoded image is displayed. It is provided to the user through the device 19 (result providing means or result providing function), the user's desired encoding style is designated, and the one according to the encoding style designated by the user is actually compressed and encoded by the compression encoding means 106. The code data may be selected (selection means or selection function).

  According to such a processing mode, a plurality of types of compression encoding processes with different encoding styles are performed by selecting the processing by the compression encoding means 106, and the results are provided to the user according to the desired encoding style. By specifying one, for example, when there is no large difference in encoding efficiency, it is possible to select one with good image quality, etc., without actually determining the characteristics of the image data, as a result, By selecting the encoding style specified by the user, the disadvantage of the JPEG2000 algorithm can be avoided.

  According to the image processing apparatus of the present embodiment, by using compression encoding means that basically performs compression encoding according to the JPEG2000 algorithm, compression encoding processing of image data having various characteristics can be handled with a single encoder. In addition to simple configuration and high efficiency, the processing content of the compression encoding means is selected based on the characteristics of the image data and switched so as to be different, so that the compression encoding processing more suitable for the characteristics of each image data and And the inconvenience of the JPEG2000 algorithm can be avoided.

  In the image processing apparatus according to the present embodiment, the determination signal related to the characteristics of the image data may be configured to be input from the outside. However, since the apparatus itself includes image characteristic determination means, the apparatus alone is appropriate. Image compression encoding processing can be performed.

  In the image processing apparatus according to the present embodiment, the processing contents of the compression encoding for the image data are made different by referring to the encoding style table that defines the selection regarding the processing in the compression encoding means for each characteristic of the image data. Thus, the invention according to claim 1 or 2 can be easily realized, and the other party (decoding side) can also facilitate the decoding process by sharing the encoding style table.

  In the image processing apparatus according to the present embodiment, as a determination signal regarding the characteristics of image data, a determination signal indicating whether the image is a natural image, a computer graphics image, a palette image, a single color image, or a binary image. Therefore, it is possible to cover the various characteristics relating to the image data, and to perform the compression encoding processing suitable for each characteristic finely.

  In the image processing apparatus according to the present embodiment, in the JPEG2000 algorithm, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing prior to entropy coding processing called coefficient modeling processing are selected according to the discrimination signal. As a target of processing, high-speed processing with good coding efficiency that does not impair the characteristics of the JPEG2000 algorithm and eliminates wasteful processing according to the characteristics of the image data by changing the processing contents according to the characteristics of the image data Is possible.

  According to the present embodiment, it is possible to clarify the processing content of compression encoding according to each characteristic of image data.

  According to the present embodiment, it is possible to realize the image processing apparatus of the present embodiment in the simplest manner by switching the processing contents according to the characteristics of the image data in units of the entire document image data. .

  In the image processing apparatus according to the present embodiment, the coding mode information of the processing content applied in the main header area of the compression-coded code data is described, and this coding mode information is referred to when decoding the code data. This makes it possible to decrypt without making a mistake.

  According to the present embodiment, the processing content is switched by a certain small region in which the document image data is divided and encoded, for example, a tile as in the invention of claim 10, and the invention of claim 11. As described above, the raster line is used as a unit, so that the invention described in claims 1 to 6 can be realized finely according to the characteristics of the image data.

  In the image processing apparatus according to the present embodiment, the encoding mode information of the processing content applied to each tile is described in the main header area of the compression encoded code data. Decoding is possible without making a mistake by referring to the information.

  In the image processing apparatus according to the present embodiment, the encoding mode information related to the switching raster line of the processing contents applied in the main header area of the compression encoded code data is described. Decoding is possible without making a mistake by referring to the information.

  In the image processing apparatus according to the present embodiment, the coding mode information of the processing content applied to the tile is described in the code data of each tile that has been compression-coded. Decoding is possible without making a mistake by referring to it.

  In the image processing apparatus according to the present embodiment, the coding mode information regarding the switching raster line of the processing content applied to the compression coded coding data of each tile is described, so that the coding mode information is decoded when the coding data is decoded. It becomes possible to decode without making a mistake by referring to.

  According to the image processing apparatus of the present embodiment, the compression coding means that basically performs compression coding according to the JPEG2000 algorithm is used, so that compression coding processing of image data having various characteristics can be handled by a single encoder. In addition, the configuration is simple and highly efficient, and the processing by the compression encoding means is selected and a plurality of types of compression encoding processing with different processing contents are performed. As a result, the processing contents with the highest encoding efficiency are obtained. Since the actual code is selected, it is possible to eliminate unnecessary processing contents by selecting the most efficient coding result without actually determining the characteristics of the image data. And inconveniences of the JPEG2000 algorithm can be avoided.

  According to the image processing apparatus of the present embodiment, the compression coding means that basically performs compression coding according to the JPEG2000 algorithm is used, so that compression coding processing of image data having various characteristics can be handled by a single encoder. In addition to being simple and highly efficient in configuration, the processing by the compression encoding means is selected and multiple types of compression encoding processing with different processing contents are performed, and the result is provided to the user and the desired processing contents are provided. Because there is no significant difference in encoding efficiency, for example, it is possible to select the one with good image quality, so that the result can be obtained without actually determining the characteristics of the image data. In particular, the inconvenience of the JPEG2000 algorithm can be avoided by selecting the processing contents designated by the user.

  In the image processing apparatus according to the present embodiment, in the JPEG2000 algorithm, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing before entropy encoding processing called coefficient modeling processing are selected as objects to be selected. Since the contents are made different, it is possible to perform high-speed processing with good coding efficiency without impairing the characteristics of the JPEG2000 algorithm and omitting wasteful processing according to the characteristics of actual image data.

  According to the image processing program of the present embodiment, the compression encoding function that basically performs compression encoding according to the JPEG2000 algorithm is used, so that a single encoder can handle compression encoding processing of image data having various characteristics. In addition to being possible and having a simple configuration and high efficiency, the processing contents of this compression encoding function are selected and switched based on the characteristics of the image data, so that the compression is more suitable for the characteristics of each image data. The encoding process can be performed, and the inconvenience of the JPEG2000 algorithm can be avoided.

  According to the image processing program of the present embodiment, the compression encoding function that basically performs compression encoding according to the JPEG2000 algorithm is used, so that a single encoder can handle compression encoding processing of image data having various characteristics. It is possible and simple in configuration, is highly efficient, selects the processing by this compression encoding function, and performs multiple types of compression encoding processing with different processing contents, and as a result, processing contents with the highest encoding efficiency As a result, it is possible to select the one with the highest coding efficiency without actually determining the characteristics of the image data. And the inconvenience of the JPEG2000 algorithm can be avoided.

  According to the image processing program of the present embodiment, the compression encoding function that basically performs compression encoding according to the JPEG2000 algorithm is used, so that a single encoder can handle compression encoding processing of image data having various characteristics. In addition to being possible, having a simple configuration and high efficiency, the processing by this compression coding function is selected and a plurality of types of compression coding processing having different processing contents are performed, and the result is provided to the user and desired processing is performed. Since it was made to specify what depends on the contents, for example, when there is no big difference in encoding efficiency, it is possible to select the one with good image quality, without actually determining the characteristics of the image data, As a result, the inconvenience of the JPEG2000 algorithm can be avoided by selecting the processing contents designated by the user.

  According to the computer-readable storage medium of the present embodiment, the same effect as the image processing program of the present embodiment can be obtained.

1 is a functional block diagram of a system that realizes a basic algorithm of a JPEG2000 system that is a premise of an embodiment of the present invention. It is explanatory drawing which shows the rectangular area | region where each component of the original image was divided | segmented. It is explanatory drawing which shows the subband in each decomposition level when the number of decomposition levels is three. It is explanatory drawing which shows a precinct. It is explanatory drawing which shows an example of the procedure which ranks a bit plane. It is. It is a schematic diagram which illustrates the code stream of the encoded image data. It is the schematic which shows the code format of JPEG2000. It is a schematic block diagram which shows the server client system containing the server computer as an image processing apparatus of one embodiment of this invention. It is a schematic block diagram which shows a server computer. It is a block diagram which shows the compression encoding process part used as the characteristic part. It is explanatory drawing which shows an encoding style table. It is a flowchart which shows the outline of the example of a compression encoding process. It is explanatory drawing which shows the example of document image data etc. which become a process target. It is explanatory drawing which shows the example of the code data at the time of the process of a page unit. It is explanatory drawing which shows the code data example at the time of the process of a tile unit. It is explanatory drawing which shows the other example of code data at the time of the process of a tile unit. It is explanatory drawing which shows the code data example at the time of the process of a raster line unit. It is explanatory drawing which shows the other example of code data at the time of the process of a raster line unit.

Explanation of symbols

121 Image Characteristic Determination Unit 122 Processing Content Switching Unit 123 Encoding Style Table 131 Character Image 132 CG Image 133 Natural Image

Claims (5)

Compression encoding means for compressing and encoding image data according to the JPEG2000 algorithm;
A plurality of types of compression encoding processes with different processing contents are performed on the image data by the compression encoding means by selecting the processing in the compression encoding means for the image data to be compression encoded. A plurality of code acquisition means for
Selecting means for selecting, as an actual code, the one with the most efficient coding content from the plurality of codes acquired by the plurality of code acquisition means,
A plurality of kinds of compression coding processing having the different processing content, Ri compression encoding Der by the coding style that corresponds to natural image, CG image, the palette image, and a monochromatic image,
The compression encoding means compresses and encodes image data by a procedure of DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, quantization processing, coefficient modeling processing, arithmetic encoding processing, and code order control processing. Among these processes, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are all subject to selection.
An image processing apparatus. Compression encoding means for compressing and encoding image data according to the JPEG2000 algorithm;
A plurality of types of compression encoding processes with different processing contents are performed on the image data by the compression encoding means by selecting the processing in the compression encoding means for the image data to be compression encoded. A plurality of code acquisition means for
Result providing means for providing the user with at least the coding efficiency and image quality of the plurality of codes for different processing contents acquired by the plurality of code acquisition means;
Selecting means for selecting the actual code according to the processing content specified by the user,
A plurality of kinds of compression coding processing having the different processing content, Ri compression encoding Der by the coding style that corresponds to natural image, CG image, the palette image, and a monochromatic image,
The compression encoding means compresses and encodes image data by a procedure of DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, quantization processing, coefficient modeling processing, arithmetic encoding processing, and code order control processing. Among these processes, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are all subject to selection.
An image processing apparatus. Installed on a computer,
A compression encoding function for compressing and encoding image data according to the JPEG2000 algorithm;
A plurality of types of compression encoding processes with different processing contents are performed on the image data by the compression encoding function by selecting the processing in the compression encoding function for the image data to be subjected to compression encoding. Multiple code acquisition function
A selection function for selecting, as an actual code, the one based on the processing content with the highest coding efficiency from the plurality of codes acquired by the multiple code acquisition function,
A plurality of kinds of compression coding processing having the different processing content, Ri compression encoding Der by the coding style that corresponds to natural image, CG image, the palette image, and a monochromatic image,
The compression encoding function compresses and encodes image data in a procedure of DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, quantization processing, coefficient modeling processing, arithmetic encoding processing, and code order control processing. Among these processes, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are all subject to selection.
An image processing program characterized by the above. Installed on a computer,
A compression encoding function for compressing and encoding image data according to the JPEG2000 algorithm;
The processing in the compression encoding function is selected for the image data to be subjected to compression encoding, and a plurality of types of compression encoding processing with different processing contents are performed on the image data by the compression encoding function. Multiple code acquisition function
A result providing function for providing a user with at least the coding efficiency and image quality of a plurality of codes for different processing contents acquired by the multiple code acquisition function;
A selection function for selecting, as an actual code, the one according to the processing content specified by the user,
A plurality of kinds of compression coding processing having the different processing content, Ri compression encoding Der by the coding style that corresponds to natural image, CG image, the palette image, and a monochromatic image,
The compression encoding function compresses and encodes image data in a procedure of DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, quantization processing, coefficient modeling processing, arithmetic encoding processing, and code order control processing. Among these processes, DC level conversion processing, color conversion processing, two-dimensional wavelet conversion processing, and quantization processing are all subject to selection.
An image processing program characterized by the above. A computer-readable storage medium storing the image processing program according to claim 3 .

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