JP6428232B2 - Image processing apparatus and image composition method - Google Patents

Description

  The present invention relates to an image processing apparatus and an image composition method.

  Image data compression techniques are used to reduce the amount of memory for storing image data and to shorten the transfer time of image data. For example, GBTC (Generalized Block Truncation Coding) is known as a compression method of image data. In this compression method, image data is divided into blocks each composed of a plurality of pixels, and fixed-length encoding, that is, compression processing at a fixed compression rate, is performed on a block basis.

  Each block has a complex area including an edge, or a simple area composed only of a flat area, and the complexity of the image differs depending on the block. For this reason, a selective GBTC compression method is known in which compression processing is performed at a different compression rate for each block according to the complexity of the block.

  When combining a plurality of image data compressed by such a GBTC compression method, each compressed image data is temporarily expanded on a memory, the expanded image data is combined, and the combined image data is then combined again. It needs to be compressed. For this reason, a memory capacity for decompressing the compressed image data to be synthesized is required.

  For the purpose of reducing the memory capacity used when combining and compressing image data, the image data is compressed by a fixed length GBTC compression method, and the compressed image data is combined based on the compression processing result. It has been proposed (see, for example, Patent Document 1).

  However, in the technique disclosed in Patent Document 1, no consideration is given to the composition processing of image data compressed at different compression rates for each block by the above-described selective GBTC compression method.

  The present invention has been made to solve such a problem, and combines a plurality of pieces of image data compressed at different compression rates for each block according to the complexity of each block constituting the image data. The purpose is to reduce the memory capacity used at the time.

  In order to solve the above-described problem, according to one embodiment of the present invention, compression processing is performed at a compression rate according to image information of each of a plurality of regions divided into a predetermined size for each of a plurality of image data. And a plurality of encoded image data composing the plurality of compressed image data according to a combination of the compression rates for each of the plurality of regions. One of the plurality of combining units, a compression rate acquiring unit that acquires the compression rate of each of the plurality of compressed image data for each of the plurality of regions, and one of the plurality of combining units based on the acquired compression rate And a synthesis output unit that synthesizes and outputs the plurality of compressed image data by the selected synthesis unit.

  ADVANTAGE OF THE INVENTION According to this invention, the memory capacity used when synthesize | combining several image data compressed by the compression rate which differs for every block according to the complexity of each block which comprises image data can be reduced.

1 is a block diagram illustrating a hardware configuration of an image processing apparatus according to an embodiment of the present invention. It is a block diagram which illustrates the functional structure of ASIC which concerns on embodiment of this invention. It is a figure which illustrates a part of image data of the compression process target by selection type GBTC which concerns on embodiment of this invention. It is a figure which illustrates the compression aspect by 4/8 compression of selective GBTC which concerns on embodiment of this invention. It is a figure which illustrates the compression aspect by 3/8 compression of selective GBTC which concerns on embodiment of this invention. It is a figure which illustrates the compression aspect by 2/8 compression of selective GBTC which concerns on embodiment of this invention. It is a figure which illustrates the data structure of the image data compressed by selective GBTC which concerns on embodiment of this invention. It is a block diagram which illustrates the functional structure of the output part which concerns on embodiment of this invention. It is a figure which illustrates a part of the read image which concerns on embodiment of this invention. It is a figure which illustrates a part of synthetic | combination image which concerns on embodiment of this invention. It is a block diagram which illustrates the functional composition of the image composition processing part concerning the embodiment of the present invention. It is a figure which illustrates the correspondence of the coding data of each compression rate which concerns on embodiment of this invention. It is a block diagram which illustrates the functional composition of the image composition processing part concerning the embodiment of the present invention. It is a figure which illustrates the input information to the synthetic | combination output part according to the combination of the compression rate of the to-be-combined image which concerns on embodiment of this invention, and the compression rate of the image for a synthesis | combination. It is a figure which illustrates the specific example of the image composition process in the image composition process part which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, an image processing apparatus that executes various types of image processing including combining processing of a plurality of compressed image data will be described as an example.

  FIG. 1 is a block diagram illustrating a hardware configuration of an image processing apparatus 1 according to this embodiment. As shown in FIG. 1, the image processing apparatus 1 according to the present embodiment includes a controller 100, an operation panel 140, an FCU (Facsimile Control Unit) 160, and a dedicated engine 180.

  In addition, the controller 100 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, an ASIC (Application Specific Integrated Circuit) 120, an HDD (Hard Disk Drive IC) ROM, and an HDD (Hard Disk Drive Rewrite) 104 Interface Card) 105. The ASIC 120 is connected to the CPU 101, the RAM 102, the HDD 103, the ROM 104, and the NIC 105 via a bus.

  The operation panel 140 includes an LCD (Liquid Crystal Display) 141 and an operation unit 142. The LCD 141, the operation unit 142, the FCU 160, and the dedicated engine 180 are connected to the ASIC 120 via a bus.

  The LCD 141 is a visual user interface for the user to check the state of the image processing apparatus 1. The operation unit 142 is a user interface for a user to input information to the image processing apparatus 1 such as a keyboard, a mouse, and a touch panel. The FCU 160 has a memory, for example, temporarily storing facsimile data received when the image processing apparatus 1 is powered off.

  The dedicated engine 180 is a configuration for realizing functions mounted on the image processing apparatus 1 such as a scanner and a printer, and includes a scanner unit 181 and a print engine 182. The scanner unit 181 captures an image of a set original according to the control of the controller 100. In the imaging operation, an imaging element such as a CCD included in the scanner unit 181 optically scans the document, and a captured image is generated based on the optical information. The print engine 182 forms an image on the paper based on the drawing information.

  The CPU 101 is a calculation unit and controls the operation of the entire image processing apparatus 1. The RAM 102 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 101 processes information. The HDD 103 is a nonvolatile storage medium capable of reading and writing information, and stores various data such as image data and document data, programs, and the like. In the present embodiment, the HDD 103 stores image data for synthesis to be combined with other image data. The image data for synthesis indicates, for example, a date, a page number, a security management number, characters such as “Mal secret”, and a stamp shape such as “Mal”.

  The ROM 104 is a read-only nonvolatile storage medium and stores programs such as firmware. The NIC 105 is a controller that controls communication with other devices such as a client terminal connected via a network such as Ethernet (registered trademark) or a LAN (Local Area Network).

  The ASIC 120 is an integrated circuit for image processing that realizes functions necessary for image processing according to the control of the CPU 101. The ASIC 120 receives read image data captured and generated by the scanner unit 181, image data stored in the HDD 103, and image data transmitted from another device connected via the NIC 105. The ASIC 120 performs various types of image processing on the input image data, and in the present embodiment, has a function of executing image combination processing for combining the input image data.

  Hereinafter, an image processing operation including an image composition process by the ASIC 120 will be described. In this description, a case will be described as an example in which image data for composition stored in the HDD 103 is combined with image data of a document to be copied and printed out. When the user performs an operation for starting a copying operation via the operation panel 140, first, a scanned image of the original to be copied is captured and read by the scanner unit 181 to generate read image data. The ASIC 120 stores the generated read image data in the RAM 102.

  Next, the ASIC 120 reads the composition image data stored in the HDD 103 and stores it in the RAM 102. Then, the ASIC 120 executes an image composition process for compositing the read image data stored in the RAM 102 and the composition image data. The ASIC 120 that has executed the image synthesis process outputs the synthesized image data to the print engine 182. As a result, the print engine 182 forms an image on the sheet based on the combined image data and outputs the image.

  In the above description, the image composition process in the copy operation has been described as an example. Processing may be performed.

  The ASIC 120 according to the present embodiment has a function of synthesizing a plurality of image data compressed by selective GBTC (Generalized Block Truncation Coding) in such an image synthesis process. The selection type GBTC is a compression method in which compression processing is performed for each of a plurality of areas divided into a predetermined size with respect to image data at a compression rate according to information on the image of the area, and details will be described later. This function is one of the gist of the present embodiment, and the functional configuration of the ASIC 120 according to the present embodiment will be described below.

  FIG. 2 is a block diagram illustrating a functional configuration of the ASIC 120 according to the present embodiment. As shown in FIG. 2, the ASIC 120 according to the present embodiment includes a compression / decompression unit 121, a RAM storage processing unit 122, an image editing unit 123, an image rotation unit 124, and an output unit 125. The compression / decompression unit 121 compresses read image data captured and generated by the scanner unit 181, image data stored in the HDD 103, image data transmitted from another device connected via the NIC 105, and the like. The compression / decompression unit 121 decompresses the compressed image data.

  The compression / decompression unit 121 according to the present embodiment performs compression / decompression by the selective GBTC. FIG. 3 is a diagram illustrating a part of image data to be compressed by the selection type GBTC. As shown in FIG. 3A, the compression processing by the selective GBTC is performed for each block unit obtained by dividing the image data into a predetermined size.

  FIG. 3B is an enlarged view of one of the blocks shown in FIG. As shown in FIG. 3B, each block is composed of, for example, 4 × 4 pixels. In this embodiment, as shown in FIG. 3B, the coordinate positions in the i direction and the j direction are determined, and the pixel value of one pixel of the block is Xij. In the present embodiment, the pixel value Xij is represented by 8 bits.

  In the selection type GBTC, for example, a plurality of compression ratios such as 4/8 compression, 3/8 compression, and 2/8 compression are determined from the original image data. The compression / decompression unit 121 selects a compression rate to be used for each block according to image information of each block (for example, an image including an edge or an image of a flat region).

  FIG. 4 is a diagram illustrating a compression mode by 4/8 compression of selective GBTC. In the case of 4/8 compression, the compression / decompression unit 121 encodes the pixel value Xij with 3-bit encoded data φij (000 to 111) as shown in FIG. Hereinafter, a process for encoding the pixel value of each pixel constituting the block by the compression / expansion unit 121 by 4/8 compression will be described with reference to FIG. Lmin shown in FIG. 4 is the minimum value of the pixel values of the pixels constituting the block, and Lmax is the maximum value of the pixel values of the pixels constituting the block.

Based on Lmin and Lmax, values P1 and P2 are obtained by the following equations (1) and (2).
P1 = (Lmax + 7Lmin) / 8 (1)
P2 = (7Lmax + Lmin) / 8 (2)

  Based on P1 and P2 obtained by the above formulas (1) and (2), the average value Qmin of pixel values that are less than or equal to P1 among the pixel values of each pixel constituting the block and the average of pixel values that are greater than P2 A value Qmax is determined.

Based on Qmin and Qmax, the average value LA and the gradation width index LD are obtained by the following equations (3) and (4).
LA = (Qmin + Qmax) / 2 (3)
LD = Qmax−Qmin (4)

Based on LA and LD obtained by the above formulas (3) and (4), the boundary values L1 to L6 shown in FIG. 4 for dividing the gradations from Lmin to Lmax are obtained as follows.
L1 = LA-LD / 8
L2 = LA-2LD / 8
L3 = LA-3LD / 8
L4 = LA + LD / 8
L5 = LA + 2LD / 8
L6 = LA + 3LD / 8

  Based on the values thus obtained, the pixel values Xij of the pixels constituting the block are encoded with the encoded data φij. Specifically, as shown in FIG. 4, φij = 111 when L6 <Xij ≦ Lmax, φij = 110 when L5 <Xij ≦ L6, and φij = 101 when L4 <Xij ≦ L5. When LA <Xij ≦ L4, φij = 100. In addition, φij = 000 when L1 <Xij ≦ LA, φij = 001 when L2 <Xij ≦ L1, φij = 010 when L3 <Xij ≦ L2, and φij = Lmin> Xij ≦ L3. 011.

  Since the original pixel value of each pixel constituting the block is composed of 8 bits, the data amount of the entire block is 4 × 4 (pixels) × 8 (bits) = 128 bits. Since the pixel value of each pixel constituting the block is encoded with 3-bit encoded data by the compression processing by 4/8 compression described above, the encoded data amount of the entire block is 4 × 4 (pixels) × 3. (Bit) = 48 bits. That is, the data amount of the entire block is 64 bits obtained by adding the data amount of LA (8 bits) and the data amount of LD (8 bits) necessary for the decompression process to the encoded data amount (48 bits). Therefore, the original image is compressed by 64 (bit) / 128 (bit) = 4/8.

When the image data compressed by 4/8 compression is expanded, the expanded pixel value X′ij is calculated as follows based on the values of LA and LD included in the compressed image data. Is done.
When φij = 111, X′ij = LA + LD / 2
When φij = 110, X′ij = LA + LD * 23/64
When φij = 101, X′ij = LA + LD * 14/64
When φij = 100, X′ij = LA + LD * 5/64
When φij = 000, X′ij = LA-LD * 5/64
When φij = 001, X′ij = LA-LD * 14/64
When φij = 010, X′ij = LA-LD * 23/64
When φij = 011, X′ij = LA-LD / 2

  FIG. 5 is a diagram illustrating a compression mode by 3/8 compression of selective GBTC. In the case of 3/8 compression, the compression / decompression unit 121 encodes the pixel value Xij with 2-bit encoded data φij (00 to 01) as shown in FIG. LA, L1, and L3 are obtained by the same procedure as that shown in FIG.

  Based on the values thus obtained, the pixel values Xij of the pixels constituting each block are encoded with the encoded data φij. Specifically, as shown in FIG. 5, φij = 11 when L2 <Xij ≦ Lmax, φij = 10 when LA <Xij ≦ L2, and φij = 00 when L1 <Xij ≦ LA. When Lmin <Xij ≦ L1, φij = 01.

  Since the pixel value of each pixel constituting the block is encoded with 2-bit encoded data by the above-described compression processing by 3/8 compression, the encoded data amount of the entire block is 4 × 4 (pixels) × 2 (Bit) = 32 bits. That is, the data amount of the entire block is 48 bits obtained by adding the data amount of LA (8 bits) and the data amount of LD (8 bits) required for the decompression process to the encoded data amount (32 bits). Therefore, the original image is compressed by 48 (bit) / 128 (bit) = 3/8.

When decompressing image data compressed by 3/8 compression, the decompressed pixel value X′ij is calculated as follows based on the values of LA and LD included in the compressed image data. The
When φij = 11, X′ij = LA + LD / 2
When φij = 10, X′ij = LA + LD / 6
When φij = 00, X′ij = LA-LD / 6
When φij = 01, X′ij = LA-LD / 2

  FIG. 6 is a diagram illustrating a compression mode by 2/8 compression. In the case of 2/8 compression, the compression / expansion unit 121 encodes the pixel value Xij with 1-bit encoded data φij (0 or 1) as shown in FIG. LA is obtained by the same procedure as that shown in FIG.

  Based on the values thus obtained, the pixel values Xij of the pixels constituting each block are encoded with the encoded data φij. Specifically, as shown in FIG. 6, φij = 1 when LA <Xij ≦ Lmax, and φij = 0 when Lmin <Xij ≦ LA.

  Since the pixel value of each pixel constituting the block is encoded with 1-bit encoded data by the above-described compression processing by 2/8 compression, the encoded data amount of the entire block is 4 × 4 (pixels) × 1. (Bit) = 16 bits. That is, the data amount of the entire block is 32 bits obtained by adding LA (8 bits) and LD (8 bits) necessary for the decompression process to the encoded data amount (16 bits). Therefore, the original image is compressed by 32 (bit) / 128 (bit) = 2/8.

When decompressing image data compressed by 2/8 compression, the decompressed pixel value X′ij is calculated as follows based on the values of LA and LD included in the compressed image data. The
When φij = 1, X′ij = LA + LD / 2
When φij = 0, X′ij = LA-LD / 2

  The compression / decompression unit 121 selects one of a plurality of different compression ratios according to the complexity of the image constituting the block, and performs compression processing at a different compression ratio for each block. . The complexity is assumed to be a standard deviation of pixel values of each pixel in the block, for example. For example, when the block is an image including an edge, the complexity of the block is high. Therefore, when the block is compressed at a high compression rate, the image quality is greatly deteriorated.

  Therefore, for example, when the complexity of the image constituting the block is higher than a predetermined threshold value (hereinafter referred to as “low pressure threshold value”), the compression / expansion unit 121 performs the block with 4/8 compression with the lowest compression rate. Is compressed.

  On the other hand, for example, when the block is a flat region, the complexity of the block is low, so that even if the block is compressed at a high compression rate, the image quality does not drop greatly. Therefore, when the complexity of the image constituting the block is lower than a predetermined threshold (hereinafter referred to as “high compression threshold”), the compression / decompression unit 121 selects the block with 2/8 compression having the highest compression rate. Compress.

  In addition, the compression / decompression unit 121 compresses the block by 3/8 compression when the complexity of the image constituting the block is not less than the high compression threshold and not more than the low compression threshold.

  FIG. 7 is a diagram exemplifying a data structure of image data compressed by the selection GBTC (hereinafter referred to as “compressed image data”). As illustrated in FIG. 7, the compressed image data includes, for example, a code header, LA, LD, pixel code, and code header (after). The code header is an identification value that identifies the compression rate. The compression / decompression unit 121 assigns an identification value as a code header of compressed image data when performing compression processing.

  LA and LD are the above-described values of LA and LD used when generating encoded data. The pixel code is encoded data generated by the compression process described above. That is, the length of the pixel code varies according to the compression rate. The code header (after) is an identification value for identifying which compression rate is used when the compressed image rotated by the image rotation unit 124 described later is decoded from the back.

  Returning to FIG. 2, the RAM storage processing unit 122 stores the image data input to the RAM storage processing unit 122 in the RAM 102. For example, image data compressed or expanded by the compression / expansion unit 121 is input to the RAM storage processing unit 122. In addition, the RAM storage processing unit 122 stores all image data input to the ASIC 120 such as read image data captured and generated by the scanner unit 181 and image data transmitted from other devices connected via the NIC 105. Is entered.

  The RAM storage processing unit 122 may directly acquire the compressed image data via the HDD 103 or the NIC 105 without using the compression / decompression unit 121. For example, when the compressed composition image data is stored in the HDD 103, the RAM storage processing unit 122 stores the compressed composition image data stored in the HDD 103 in the RAM 102 when the image composition process is performed. Remember.

  The image editing unit 123 performs various editing processes on the image data stored in the RAM 102 according to the control of the CPU 101. The image rotation unit 124 rotates image data stored in the RAM 102 under the control of the CPU 101.

  The output unit 125 outputs image data stored in the RAM 102 to each unit such as the print engine 182 and the HDD 103 under the control of the CPU 101. Further, the output unit 125 synthesizes the image data stored in the RAM 102 and the image data for synthesis under the control of the CPU 101 and outputs them to each unit.

  For example, when image data subjected to image processing such as image editing, image rotation, and image composition is output to the print engine 182, the print engine 182 forms an image on the paper based on the image data and outputs the image. To do. Further, for example, when image data subjected to each image processing is output to the HDD 103, the image data subjected to the image processing is stored in the HDD 103. Further, the output unit 125 may output the image data subjected to each image processing to another device connected to the network via the NIC 105.

  FIG. 8 is a block diagram illustrating a functional configuration of the output unit 125. As shown in FIG. 8, the output unit 125 includes an image composition processing unit 130 and a selection output unit 126. When a plurality of image data are input, the image composition processing unit 130 synthesizes the plurality of input image data.

  FIG. 9 is a diagram illustrating a part of a read image generated by reading a document by the scanner unit 181 stored in the RAM 102 by the RAM storage processing unit 122. FIG. 10 is a diagram exemplifying a part of a composite image of the read image shown in FIG. 9 and the composite image stored in the RAM 102 by the RAM storage processing unit 122. The dotted lines shown in FIG. 9 and FIG. 10 indicate the divided blocks as the processing unit, but the dotted lines are not displayed in the actual image.

  For example, the user performs an operation of adding a composite image on the read image via the operation panel 140 as shown in FIG. When this operation is performed, the image data of the block of the read image and the image data of the block of the image for synthesis are input to the image synthesis processing unit 130 at the position where the synthesized image is arranged under the control of the CPU 101. At that time, the CPU 101 performs control so that the position of the block of the image for synthesis and the block of the read image coincide with each other, and controls so that one block of the image for synthesis does not cross over a plurality of blocks of the read image. To do.

  When a plurality of pieces of image data in units of blocks are input, the image composition processing unit 130 performs a process for compositing these image data. At this time, if the plurality of input image data is compressed image data based on the selection type GBTC, the image composition processing unit 130 synthesizes the compressed image data without decompressing the input compressed image data. This process is one of the gist of the present embodiment, and details will be described later.

  On the other hand, block image data at a position other than the position where the composite image is added is directly input to the selection output unit 126 without being input to the image composition processing unit 130. The selection output unit 126 is a multiplexer (MUX) that outputs the image data itself or the image data synthesized by the image synthesis processing unit 130 (hereinafter, “synthesized image data”). That is, the selection output unit 126 outputs a block of composite image data at a position where the composite image is added, and outputs a block of image data at other positions.

  Next, details of the image composition processing by the image composition processing unit 130 will be described. FIG. 11 is a block diagram illustrating a functional configuration of the image composition processing unit 130. In the functional configuration shown in FIG. 11, a case will be described as an example where the image composition processing unit 130 synthesizes the composition image data compressed in 2/8 compression and stored in advance in the HDD 103.

  Hereinafter, the compressed image data for synthesis is simply referred to as “image data for synthesis”. Also, the image data that has been subjected to the compression process to be combined with the image data for synthesis is referred to as “image data to be combined”. Further, the processing unit in the image composition processing unit 130 is one block (4 × 4 pixels), and even when “image data for composition” and “image data to be synthesized” are described, the image data is one block. And

  As illustrated in FIG. 11, the image composition processing unit 130 includes a compression rate determination unit 131, 2/8 × 2/8 composition unit 132-1, 3/8 × 2/8 composition unit 132-2, 4/8 ×. 2/8 combining section 132-3 and combining output section 133 are included. Hereinafter, the 2/8 × 2/8 combining unit 132-1, 3/8 × 2/8 combining unit 132-2, and 4/8 × 2/8 combining unit 132-3 will be referred to as “combining unit 132-1”. ”,“ Synthesizer 132-2 ”, and“ synthesizer 132-3 ”, and may be collectively referred to as“ synthesizer 132 ”.

  The compression rate determination unit 131 determines the compression rate of the combined image data input to the image composition processing unit 130. That is, the compression rate determination unit 131 functions as a compression rate acquisition unit that acquires the compression rate of the compressed image data. Specifically, for example, the compression rate determination unit 131 determines the compression rate with reference to the code header shown in FIG. Based on the determined compression rate, the compression rate determination unit 131 inputs the composite image data to any one of the synthesis units 132 and inputs the determined compression rate information to the synthesis output unit 133. To do.

  Specifically, the compression rate determination unit 131 inputs the combined image data to the combining unit 132-1 when the combined image data is compressed by 2/8 compression. In addition, when the combined image data is compressed by 3/8 compression, the compression rate determination unit 131 inputs the combined image data to the combining unit 132-2. Further, when the combined image data is compressed by 4/8 compression, the compression rate determination unit 131 inputs the combined image data to the combining unit 132-3.

  The synthesizing unit 132 is a synthesizing circuit that synthesizes encoded data constituting a plurality of compressed image data according to the combination of the compression rate of the synthesized image data and the compression rate of the synthesis image data. When both the composition image data are input, the composite image data is output. Specifically, the synthesis unit 132 outputs the image data for synthesis as synthesized image data. That is, in the present embodiment, as shown in FIG. 10, the block of the image data to be combined is replaced with the block of image data for synthesis.

  When the compression rate of the image data for synthesis and the compression rate of the image data to be synthesized are different, the synthesis unit 132 converts the encoded data of each pixel constituting the image data for synthesis to any one of the plurality of compressed image data to be synthesized. It is necessary to convert it according to the compression ratio. In the present embodiment, a case where encoded data is converted in accordance with the lowest compression rate will be described as an example.

  Since the compression unit 132-1 has the same compression rate for both image data, it is not necessary to convert the encoded data of the image data for synthesis, and the image data for synthesis is input to the synthesis output unit 133 as it is. The synthesizing unit 132-2 converts the 1-bit encoded data of the image data for synthesis into 2-bit encoded data of 3/8 compression.

  FIG. 12 is a diagram illustrating a correspondence relationship between encoded data of each compression rate. For example, when the encoded data of the image for synthesis is “1”, the synthesizing unit 132-2 converts the encoded data into “11” or “10” as illustrated in FIG. To enter. It is assumed in the synthesis unit 132-2 that which encoded data is to be converted is set in advance.

  The synthesizing unit 132-3 converts the 1-bit encoded data of the image data for synthesis into 3-bit encoded data of 4/8 compression. For example, when the encoded data of the composition image is “1”, the composition unit 132-3 selects “111”, “110”, “101”, or “100” as illustrated in FIG. The result is converted and input to the composite output unit 133. It is assumed that which encoding data is to be converted is set in advance in the synthesis unit 132-3.

  The composite output unit 133 is a multiplexer (MUX) that outputs the composite image data input from one of the composite units 132 based on the compression rate information input from the compression rate determination unit 131. For example, when the input compression rate information indicates 3/8 compression, the composite output unit 133 outputs the composite image data input from the composite unit 132-2. The processing by each unit of the image composition processing unit 130 described above is repeated for each block.

  Next, the configuration of the image composition processing unit 130 when the compression rate of the composition image is different for each block will be described. FIG. 13 is a block diagram illustrating a functional configuration of the image composition processing unit 130 when the compression rate of the composition image is different for each block. As illustrated in FIG. 13, the image composition processing unit 130 includes a compression rate determination unit 134, a composition image compression rate determination unit 135, 2/8 × 2/8 composition unit 132-1, 3/8 × 2/8 composition. Section 132-2, 4/8 × 2/8 composition section 132-3, 3/8 × 3/8 composition section 132-4, 4/8 × 3/8 composition section 132-5 and 4/8 × 4 / 8 synthesis unit 132-6 and synthesis output unit 136.

  The 2/8 × 2/8 combining unit 132-1, the 3/8 × 2/8 combining unit 132-2, and the 4/8 × 2/8 combining unit 132-3 are the same as the combining unit 132 illustrated in FIG. -1, 132-2, 132-3. Hereinafter, the 3/8 × 3/8 combining unit 132-4, the 4/8 × 3/8 combining unit 132-5, and the 4/8 × 4/8 combining unit 132-6 will be referred to as the “combining unit 132-4”. ”,“ Synthesis unit 132-5 ”, and“ synthesis unit 132-6 ”, and the synthesis units 132-1 to 132-6 may be collectively referred to as“ synthesis unit 132 ”.

  The compression rate determination unit 134 determines the compression rate of the combined image data, similarly to the compression rate determination unit 131 illustrated in FIG. Further, the compression rate determination unit 134 inputs the combined image data to the combining unit 132 that receives the compressed image data of the determined compression rate in the combining unit 132. For example, when the combined image data is compressed by 2/8 compression, the compression rate determination unit 131 inputs the combined image data to the combining units 132-1, 132-2, and 132-3. Further, the compression rate determination unit 134 inputs information on the determined compression rate to the composite output unit 136.

  The composition image compression rate determination unit 135 determines the compression rate of the composition image data input to the image composition processing unit 130. That is, the composition image compression rate determination unit 135 functions as a compression rate acquisition unit that acquires the compression rate of the compressed image data. Specifically, for example, the composition image compression rate determination unit 135 determines the compression rate with reference to the code header illustrated in FIG. 7 of the composition image data. Further, the composition image compression rate determination unit 135 inputs the composition image data to the composition unit 132 that receives compressed image data of the determined compression rate in the composition unit 132. Further, the composition image compression rate determination unit 135 inputs the determined compression rate information to the composition output unit 136.

  The synthesizing unit 132 is a synthesizing circuit that performs the same processing as that of the synthesizing unit 132 shown in FIG. In the present embodiment, when the compression rate of the image data for synthesis is higher than the compression rate of the image data to be combined, the combining unit 132 sets the encoded data of the image data for synthesis to the length of the encoded data of the image data to be combined. In other cases, the image data for synthesis is input to the synthesis output unit 136 as it is.

  The composition output unit 136 outputs a composite image data input from any one of the composition units 132 based on the compression rates input from the compression rate determination unit 134 and the image compression rate determination unit 135 for composition. It is. FIG. 14 is a diagram exemplifying input information to the synthesis output unit 136 according to the combination of the compression rate of the image to be synthesized and the compression rate of the image for synthesis.

  A to F shown in FIG. 14 correspond to inputs A to F from the synthesis units 132-1 to 132-6 shown in FIG. That is, as shown in FIG. 14, for example, when the compression rate of the combined image data is 4/8 compression and the compression rate of the image data for synthesis is 2/8 compression, the combining output unit 136 The composite image data input from 132-3 (input C) is output.

  FIG. 15 is a diagram illustrating a specific example of the image composition processing in the image composition processing unit 130. Here, a case will be described as an example where composite image data compressed by 4/8 compression and composite image data compressed by 2/8 compression are input to the image composition processing unit 130. Based on the determination result of the compression ratio, the compression rate determination unit 134 inputs the combined image data to the combining units 132-3, 132-5, and 132-6 to which 4/8 compressed image data is input.

  The composition image compression rate determination unit 135 inputs the composition image data to the composition units 132-1, 132-2, and 132-3 to which 2 / 8-compressed image data is input based on the determination result of the compression rate. To do. The composite output unit 136 outputs the input C, that is, the input from the composite unit 132-3, as composite image data based on the input information shown in FIG. Note that both the image data to be combined and the image data for combining are input to the combining unit 132-3. The output composite image data is obtained by converting the encoded data of the composite image data into encoded data having a code length of 4/8 compression.

  As described above, the image processing apparatus 1 according to the present embodiment includes a plurality of combining units corresponding to combinations of compression rates based on the selective GBTC, and the compression rate of each block of each of a plurality of image data to be combined. A synthesis unit corresponding to the combination is selected and a synthesized image is output. This makes it possible to synthesize a plurality of compressed image data compressed with different code lengths by the selective GBTC for each block without decompressing. That is, according to the present embodiment, it is possible to reduce the memory capacity used when combining a plurality of image data compressed at different compression rates for each block according to the complexity of the block of image data.

  In the above embodiment, the case where the image data for synthesis is stored in the HDD 103 in advance has been described as an example. However, this is merely an example, and the composition image data is acquired from another device via the NIC 105, generated by reading a document by the scanner unit 181 or generated from font data as appropriate. It only needs to be acquired.

  In addition, the synthesis unit 132 according to the present embodiment has been described with respect to an example in which the encoded data of the image data for synthesis is converted in accordance with the lowest compression rate when the compression rates of the plurality of image data to be synthesized are different. . In this case, it is possible to output a composite image in which deterioration in image quality is suppressed as much as possible.

  In addition, the synthesizing unit 132 may convert the encoded data of the image data for synthesis in accordance with the highest compression rate. In this case, for example, when the encoded data of the image data for synthesis is “11”, the synthesizing unit 132 converts the encoded data to “1” as illustrated in FIG. Can be adjusted to the compression rate. With such a configuration, since the code length of the encoded data of the image data for synthesis does not become longer due to the conversion, it is possible to minimize the amount of memory necessary for the image synthesis process.

1 Image processing unit 100 Controller 101 CPU
102 RAM
103 HDD
104 ROM
105 NIC
120 ASIC
Reference Signs List 121 Compression / decompression unit 122 RAM storage processing unit 123 Image editing unit 124 Image rotation unit 125 Output unit 126 Selection output unit 130 Image composition output unit 131, 134 Compression rate determination unit 132 Composition unit 133, 136 Composition output unit 135 Image compression for composition Rate judgment unit 140 Operation panel 141 LCD
142 Operation unit 160 FCU
180 Dedicated engine 181 Scanner unit 182 Print engine

JP 2009-118240 A

Claims (6)

An image processing apparatus that synthesizes a plurality of compressed image data obtained by performing compression processing at a compression rate corresponding to image information of each of a plurality of areas divided into a predetermined size for each of a plurality of image data. There,
A plurality of combining units that combine the plurality of pieces of encoded data constituting the plurality of compressed image data according to the combination of the compression rates for each of the plurality of regions;
A compression rate acquisition unit for acquiring a compression rate of each of the plurality of compressed image data for each of the plurality of regions;
Based on the acquired compression ratio, one of the plurality of combining units is selected for each of the plurality of regions, and the plurality of compressed image data is combined and output by the selected combining unit An image processing apparatus comprising: an output unit. The image processing according to claim 1, wherein the synthesizing unit converts the plurality of pieces of encoded data into encoded data having a code length of the lowest compression rate among the acquired compression rates, and combines the converted data. apparatus. The image processing according to claim 1, wherein the combining unit converts the plurality of pieces of encoded data into encoded data having a code length of the highest compression rate among the acquired compression rates, and combines the converted data. apparatus. The synthesizing unit arranges image data for synthesis that is the compressed image data to be synthesized with the synthesized image data among the plurality of regions of the synthesized image data that is the compressed image data to be synthesized with the image data. The image processing apparatus according to claim 1, wherein the area is replaced with the area of the image data for synthesis. The image processing according to any one of claims 1 to 4, wherein the compression rate acquisition unit acquires the compression rate based on information for identifying the compression rate included in the compressed image data. apparatus. In an image processing apparatus that synthesizes a plurality of compressed image data obtained by performing compression processing at a compression rate according to image information of each of a plurality of regions divided into a predetermined size for each of a plurality of image data An image composition method comprising:
The image processing apparatus includes a plurality of combining units that combine a plurality of pieces of encoded data constituting the plurality of compressed image data according to a combination of the compression rates for each of the plurality of regions.
Obtaining a compression rate of each of the plurality of compressed image data for each of the plurality of regions;
Selecting one of the plurality of combining units for each of the plurality of regions based on the acquired compression ratio;
The image combining method, wherein the plurality of compressed image data are combined by the selected combining unit.