JP4864490B2 - Image output system, program, and information recording medium - Google Patents

Description

  The present invention relates to a technique for realizing printing (collectively referred to as toner save printing) that saves consumption of color materials (toner, ink, etc.) in a printer, a copying machine, and the like, and more particularly, foreground, mask, and background. The present invention relates to a technique for reproducing document image data for toner save printing from a code of a structured document consisting of

  The simplest method for realizing toner save printing is, for example, as described in Patent Document 1, in which gamma correction is applied to the image data to be printed in the direction of decreasing the density value, or a simple method is used. This is a method of performing a thinning process. However, such a method has problems that it is difficult to read thin characters or that thin lines disappear, as described in Patent Document 1.

  Japanese Patent Application Laid-Open No. 2004-151867 describes an invention for realizing toner saving at the image data encoding stage. In this invention, the image data is divided into small blocks, subband conversion is performed in units of blocks, and for blocks with a large high frequency coefficient, the subband conversion coefficient is corrected as it is or to the high density side before entropy coding, For a block with a small high frequency coefficient, the subband transform coefficient is converted to 0 (white) and then entropy encoded. Therefore, when the generated code is decoded, an image consisting only of an edge (contour) in the original image or an image in which the edge is enhanced is obtained. The toner can be saved when printing such a reproduced image, and it is less likely that the characters are difficult to see or the thin lines disappear.

JP-A-11-136515

  However, although the invention described in Patent Document 1 is suitable for the purpose of generating a code of a test document to be preliminarily saved with toner, printing a general document image with toner in a printer. Obviously, it is difficult to apply to the purpose and the purpose of toner-saving printing of a general document image stored in a copying machine or the like.

  On the other hand, methods such as printers and copiers that perform gamma correction or simple thinning processing in the direction of decreasing the density value of image data to be printed have the problems described above. .

  Therefore, an object of the present invention is to realize toner-saving printing that does not have the above-described problems by an approach different from the above-described conventional technique. The present invention is applicable to an image output system such as a printer in which a structured document code including a foreground, a mask, and a background is input, and a copying machine that stores the read document as a structured document code. In addition, the present invention can be applied to an image output system that outputs a structured document stored in a personal computer or the like to a type of printer that cannot process the structured document as it is.

  Here, the structured document according to the present invention will be described. There is a technique called MRC (Mixed Raster Contents) of Xerox Corporation in the United States as a technique for compressing a document in which characters / line drawings and pictures are mixed. In the MRC, as schematically shown in FIG. 1, a document image 1 is usually converted into a foreground 2 representing character color information, a mask 3 representing a character area in units of pixels, and a background 4 representing image information of a picture such as a photograph. Are divided (structured), and encoding is performed for each layer. In the example of FIG. 1, the foreground 2 is encoded by JBIG, the mask 3 is encoded by MMR, and the background 4 is encoded by JPEG, but this is merely an example. In the example, the mask is binary data, but it can be multi-valued data as will be described later.

  In addition, JPM (JPEG2000 Muli Layer), which enables selection of JPEG2000 as a foreground, mask, and background encoding method of the MRC model, has been standardized (IS 15444-6).

  A method for reproducing the document image data from the code of the structured document such as MRC or JPM is as follows. First, the foreground, mask and background are decoded. Next, the foreground and the background are synthesized according to the mask. In this composition, when the mask is binary black and white, the composition pixel value = the foreground pixel value at the pixel position where the mask value is 1 (black), and the composition pixel value = the background pixel value at the pixel position where the mask value is 0 (white). And In other words, the opacity is 1 at the pixel position where the mask value is 1, and the opacity is 0 (transparency is 1) at the pixel position where the mask value is 0, and the foreground is superimposed on the background. In this case, the mask has a function of selecting the foreground and the background.

The mask can be multivalued. For example, when each pixel of the mask takes an 8-bit positive value (including 0), the composite image value = (255−mask value) / 255) × background value + (mask value / 255) × foreground for each pixel. A value obtained by taking a weighted average of the foreground value and the background value depending on the value is a composite image value. In this case, the mask has a function of controlling the display ratio (opacity or transparency) of the foreground and the background.

  In the embodiment of the present invention to be described later, the background code of the structured document is a JPEG2000 code, and therefore an outline of JPEG2000 will be described here. However, as will be described later, the present invention can also be applied when a code other than JPEG2000 is used as the background code.

  FIG. 2 is a block diagram for explaining a JPEG2000 encoding algorithm. The color image is divided into tiles that are rectangular blocks that do not overlap for each component (the number of tile divisions ≧ 1). Compression / decompression is performed independently for each component and for each tile.

  First, the data of each tile of each component is converted from, for example, an RGB space to a YCbCr space in the processing block 11. When the original data has a positive integer value such as RGB data, a DC level shift for subtracting half of the dynamic range is also performed. The Y, Cb, and Cr component data after the conversion is spatially divided into subbands (frequency bands) by applying a two-dimensional wavelet transformation (forward transformation) for each tile in the processing block 12.

  FIG. 3 shows subband division when the number of decomposition levels is three. The two-dimensional wavelet transform is applied to the Y, Cb, and Cr components of each tile shown in FIG. 3A to divide the subbands (1LL, 1HL, 1LH, and 1HH) shown in FIG. . The subbands (2LL, 2HL, 2LH, 2HH) shown in FIG. 3C are obtained by performing two-dimensional wavelet transform on the coefficients of the 1LL subband, which is the low frequency subband of the decomposition level 1 (the highest layer). ). Two-dimensional wavelet transform is applied to the coefficients of the 2LL subband, which is the low frequency subband of the decomposition level 2, and the subband (3LL, 3LL,) of the decomposition level 3 (the lowest layer in this example) shown in FIG. 3HL, 3LH, 3HH).

  Returning to FIG. JPEG2000 defines an irreversible wavelet transform called 9 × 7 transform and a reversible wavelet transform called 5 × 3 transform. When the 9 × 7 transform is used, in the processing block 13, the wavelet coefficients of each component are subjected to linear quantization (including normalization for correction of subband gain and the like) for each subband. Then, in processing block 14, target bits for encoding are determined in the designated encoding order, a context is generated from bits around the target bits, and wavelet coefficients are entropy-encoded by probability estimation from the context and target bits. To do.

  More specifically, as shown in FIG. 4, each subband is divided into non-overlapping rectangular areas called precincts. Three rectangular regions spatially matching the LH, HL, and HH subbands at the same decomposition level are treated as one precinct. However, in the LL subband, one rectangular area is treated as one precinct. A precinct roughly represents a position in an image. A code block obtained by further dividing the precinct into rectangles is a unit of entropy coding. In JPEG2000, bit-plane coding called MQ coding is performed on wavelet coefficients for each code block and in bit-plane order.

  Next, in processing block 15, unnecessary entropy codes are discarded, and necessary entropy codes are collected to generate a packet. The processing block 16 arranges the packets in a predetermined order and adds a necessary header or the like to form one code stream (code). Here, the packet is a packet that collects a part of codes of all code blocks included in the precinct (for example, a code that collects codes of the MSB to the third bit plane of all code blocks). It has a header.

  On the other hand, the decoding (decompression) process generates image data from the code stream of each tile of each component by a process just opposite to the encoding process. FIG. 5 is a block diagram for explaining a decoding algorithm.

  In processing block 21, the header information added to the input code stream is interpreted, broken down into code streams of each tile of each component, and further broken down into packets. Next, the processing block 22 divides the packet into codes for each code block, and the processing block 23 decodes the code for each code block. In this bit-plane decoding, a target bit position is determined in a specified order (known from header information), a context is generated from its peripheral bits (decoded), and decoding (MQ) is performed from this context and the code stream by probability estimation. Decoding) to generate the target bit and write it into the target bit position. The wavelet coefficients decoded in this way are subjected to inverse quantization (including inverse normalization) in the processing block 24 in the case of a code using 9 × 7 transform. Next, two-dimensional inverse wavelet transform is performed in the processing block 25 to restore the tile images of the Y, Cb, and Cr components. The restored YCbCr data is returned to the original RGB color system data by being subjected to DC inverse level shift and inverse color conversion in the processing block 26.

The invention described in claim 1
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code encoded for each component of luminance and chrominance, and the toner saving process corrects the pixel value of the luminance component in the decoding process of the background code. In the image output system, the correction degree for the small pixel value is larger than the correction degree for the large pixel value in the correction process.

The invention according to claim 2
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code that is divided into subbands for each of the luminance and color difference components, and the toner saving process calculates the coefficient value of the low frequency subband of the luminance component in the decoding process of the background code. The image output system is a process of correcting to an increasing side, wherein the degree of correction for a small coefficient value in the correction process is larger than the degree of correction for a large coefficient value.

The invention described in claim 3
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code that is hierarchically sub-band divided for each component of luminance and chrominance, and the toner saving process is performed in the decoding process of the background code in a hierarchy below a predetermined hierarchy of the luminance component. The image output system is a process for correcting the coefficient values of the subbands to be increased so that the degree of correction for a small coefficient value is larger than the degree of correction for a large coefficient value in the correction process. .

The invention according to claim 4
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code obtained by subband division for each component of luminance and color difference, and the coefficient value of each subband is normalized, and the toner saving process is a process of decoding the background code , A process of correcting the normalized denominator value used for denormalizing the coefficient value of the low frequency subband of the luminance component to a side where the normalized denominator value is increased from the standard value. In the image output system, the degree of correction of the normalized denominator value used is greater than the degree of correction of the normalized denominator value used for denormalization with respect to a large coefficient value.

The invention according to claim 5
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code in which subbands are hierarchically divided for each component of luminance and color difference, and the coefficient value of each subband is normalized. In the decoding process, a process of correcting the normalized denominator value used for denormalization with respect to the coefficient value of the subband of the hierarchy below the predetermined hierarchy of the luminance component to the side to increase from the standard value, The image output system is characterized in that the degree of correction of a normalized denominator value used for denormalization with respect to a small coefficient value is larger than the degree of correction of a normalized denominator value used for denormalization with respect to a large coefficient value.

The invention described in claim 6
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code that is divided into subbands for each of the luminance and color difference components, and the toner saving process calculates the coefficient value of the low frequency subband of the luminance component in the decoding process of the background code. In the process of correcting the coefficient value of the luminance component, the coefficient value of the low frequency subband of the color difference component is corrected to the side of decreasing the absolute value thereof. In the process of correcting the coefficient value of the chrominance component greater than the degree of correction with respect to the coefficient value with a large correction value, the degree of correction with respect to the coefficient value with a large absolute value is larger than the degree of correction with respect to the coefficient value with a small absolute value. This is an image output system.

The invention described in claim 7
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code that is hierarchically sub-band divided for each component of luminance and chrominance, and the toner saving process is performed in the decoding process of the background code in a hierarchy below a predetermined hierarchy of the luminance component. Correction processing to increase the coefficient value of the sub-band, and processing to correct the coefficient value of the sub-band below the predetermined layer of the color difference component to the side to decrease its absolute value, In the process of correcting the coefficient value, the degree of correction for the small coefficient value is larger than the degree of correction for the large coefficient value. In the process of correcting the coefficient value of the color difference component, the degree of correction for the coefficient value having a large absolute value is The image output system is characterized in that the degree of correction is larger than the coefficient value having a small absolute value.

The invention described in claim 8
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code obtained by subband division for each component of luminance and color difference, and the coefficient value of each subband is normalized, and the toner saving process is a process of decoding the background code In the process of correcting the normalized denominator value used for denormalizing the coefficient value of the low frequency subband of the luminance component to the side to increase from the standard value, and denormalizing the coefficient value of the low frequency subband of the color difference component And a process for correcting the normalized denominator value to be used to decrease the standard denominator value from the standard value. The degree of correction of the normalized denominator value used is larger than the degree of correction of the normalized denominator value used for denormalization for a large coefficient value, and the color difference control In the process of correcting the normalized denominator value used for inverse normalization of the coefficient value of the component, the degree of correction of the normalized denominator value used for inverse normalization for the coefficient value with a large absolute value is the inverse of the coefficient value with a small absolute value. It is an image output system characterized by being larger than the degree of correction of a normalized denominator value used for normalization.

The invention according to claim 9
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code in which subbands are hierarchically divided for each component of luminance and color difference, and the coefficient value of each subband is normalized. In the decoding process, a process of correcting the normalized denominator value used for denormalization of the subband coefficient values of the sub-bands of the luminance component lower than the predetermined hierarchy to a side to increase from the standard value, and a hierarchy of the color difference component lower than the predetermined hierarchy And correcting the normalized denominator value used for the denormalization of the coefficient value of the luminance component. Normalized denominator value used for inverse normalization for large coefficient values when the degree of correction of the normalized denominator value used for denormalization for small coefficient values in processing In the process of correcting the normalized denominator value used for denormalizing the coefficient value of the color difference component that is larger than the degree of correction, the degree of correction of the normalized denominator value used for denormalization for the coefficient value having a large absolute value is: An image output system characterized by being larger than a degree of correction of a normalized denominator value used for denormalization with respect to a coefficient value having a small absolute value.

The invention according to claim 10 is:
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code divided into subbands for each component of luminance and color difference, and a high-accuracy mode for performing the toner saving process on the pixel value of the luminance component in the decoding process of the background code, and a background A high-speed mode for performing the toner saving process on the coefficient value of the low frequency subband of the luminance component or the coefficient value of the low frequency subband of the luminance component and the color difference component in the decoding process of An image output system capable of selecting a high-accuracy mode or the high-speed mode.

The invention according to claim 11
Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
The background code of the structured document is a code that is hierarchically sub-band divided for each component of luminance and color difference, and a high-accuracy mode that performs the toner saving process on the pixel value of the luminance component in the decoding process of the background code In the decoding process of the background code, the toner is applied to the coefficient values of the subbands of the luminance component and lower layers of the luminance component, or to the coefficient values of the subbands of the luminance component and the color difference component of the lower layer. An image output system having a high-speed mode for performing a save process, wherein the high-precision mode or the high-speed mode can be selected.

A thirteenth aspect of the present invention is a program that causes a computer to function as the document image reproduction processing means according to any one of the first to ninth aspects.

A fourteenth aspect of the present invention is a computer-readable information recording medium in which a program for causing a computer to function as the document image reproduction processing means according to any one of the first to ninth aspects is recorded.

According to the first to ninth aspects of the present invention, the document image reproduction processing means performs toner save processing on the background of the structured document, thereby enabling printing with reduced color material consumption (toner save printing). is there. As described above, in a structured document such as MRC or JPM, the background is usually image information of a picture such as a photograph, the mask is character area information, and the foreground is character color information. In general documents, the most important information is character information, and the pattern is often positioned to assist the character information. Therefore, the toner save process is applied only to the background, which is the pattern portion in the document image, and the mask and foreground are not processed. Can be avoided.

The image output means normally converts the input image data into a CMYK signal corresponding to a color material, and performs image processing for generating a print signal by performing gamma correction and halftone processing. When the toner saving process is performed by the image output unit, the configuration related to the image processing in the image output unit is likely to be complicated, and the processing speed is likely to decrease . Since DOO Nasebu process performed by the document image reproduction processing unit, since it is sufficient to same image processing even when even normal printing when the toner saving printing by the image output means, complicating and slowing of the configuration of the image output means There is nothing.

In the background code decoding process, toner save processing is applied to the luminance component, or to the luminance component and the color difference component, and both foreground and mask decoding processing and background and foreground combining processing Independent of toner save process. This is advantageous for simplification of hardware or software for realizing the document image reproduction processing means.

According to the first to fifth aspects of the present invention, the background to be decoded becomes a bright and light (thin) image by the toner saving process, so that the pattern portion of the reproduced document image data becomes a bright and light image. The pattern portion consumes less color material during printing. Therefore, it is possible to save the color material consumed for printing the document image data, compared to the case where the toner saving process is not performed. Further, even if the toner save process is performed, many of the high-frequency components of the background are preserved, so that the contents of the pattern portion do not become indistinguishable. According to the inventions according to claims 2 to 5 , since the number of coefficients to be subjected to toner save processing is significantly smaller than the total coefficient (total number of pixels) of the luminance component, toner save processing is performed on the pixel value data of the luminance component. As compared with the invention according to claim 1 , the toner save process can be executed at a higher speed.

According to the inventions according to claims 6 to 9 , since the background to be decoded becomes a light (thin) image with a light and weak hue by the toner saving process, the picture portion of the reproduced document image data has a bright and colored image. A weak light image is obtained, and such a pattern portion requires less color material consumption during printing. Therefore, it is possible to save the color material consumed for printing the document image data, compared to the case where the toner saving process is not performed. Further, even if the toner save process is performed, many of the high-frequency components of the background are preserved, so that the contents of the pattern portion do not become indistinguishable. Further, since the number of coefficients to be subjected to the toner saving process is significantly smaller than the total coefficient (total number of pixels) of the luminance and color difference components, the toner saving process can be executed at high speed.

According to the tenth , eleventh and twelfth aspects of the invention, it is possible to select toner save printing in the high accuracy mode or toner save printing in the high speed mode. According to the twelfth aspect of the present invention, it is possible to confirm the printing condition when the high-precision mode or the high-speed mode is selected before actually executing toner save printing on the document image data. Judgment as to which to select becomes easier.

According to the inventions according to claims 13 and 14 , the document image according to the inventions according to claims 1 to 9 is used by using a built-in computer of an image output device such as a printer or a copying machine, or a computer such as a personal computer connected to the printer. A reproduction processing means can be constructed to execute toner save printing of document image data.

  FIG. 6 is a block diagram for explaining an embodiment of the present invention. In FIG. 1, a document image reproduction processing unit 100 is means for reproducing document image data from a code of an input structured document. Here, it is assumed that the document image data to be reproduced is RGB data. In the document image reproduction processing unit 100, when a mode for performing toner save (toner save mode) is designated by a mode designation signal, the reproduced document image data can be used for toner save printing. Includes a toner save processing unit 101 that performs the process (referred to as toner save process) on the background of the structured document.

  The document image data reproduced by the document image reproduction processing unit 100 is input to the image output unit 102. The image output unit 102 includes an image processing unit 103 and an image forming unit 104. The image creating unit 104 is a unit that prints an image on a medium such as paper using a color material. The image processing unit 103 converts input document image data (RGB data here) into a print signal suitable for the image forming unit 104.

  Here, the image forming unit 104 uses an electrophotographic image forming engine or an ink jet image forming engine that uses cyan (C), magenta (M), yellow (Y), and black (K) color materials. An image shall be printed. In this case, the image processing unit 103, for example, a color conversion processing unit 105 that converts RGB signals into CMYK signals, a gamma correction unit 106 that performs gamma correction on the CMYK signals, and dither processing on the CMYK signals after gamma correction. And a halftone processing unit 107 that performs halftone processing such as error diffusion. However, this is merely an example, and the image processing unit 103 may include means such as filter processing for smoothing and edge enhancement, and other image quality improvement processing. When the print signal output from the image processing unit 103 is input to the image forming unit 104, the document image data reproduced by the document image reproduction processing unit 100 is printed by the image forming unit 104.

  The processing content in the image processing unit 103 is the same when the toner save mode is designated by the mode instruction signal and when the normal mode in which toner save is not performed is designated.

  In such an image output system, the document image reproduction processing unit 100 and the image output unit 102 are combined into one apparatus such as a printer or a copier, or the document image reproduction processing unit 100 and the image output unit 102 are physically combined. It can take the form of a separate device. As an example of the latter form, the image output unit 102 is a printer or a multi function printer (MFP), and the document image reproduction processing apparatus 100 is implemented as a program (for example, a printer driver) on a computer such as a personal computer. The Specific examples of the above system configuration will be described later.

  FIG. 7 is a block diagram showing a preferred internal configuration of the document image reproduction processing unit 100. As shown in FIG. As illustrated, the document image reproduction processing unit 100 includes a foreground decoding unit 110, a mask decoding unit 111, and a background decoding unit 112 that perform decoding processing of a foreground code, a mask code, and a background code of a structured document; The composition processing unit 113 synthesizes the document image data from the foreground, mask, and background decoded by each of these decoding units by the method described above.

  Since the toner save processing unit 101 performs toner save processing on the background of the structured document, the toner save processing unit 101 can be provided at the subsequent stage of the background decoding unit 112. Provided inside. In this way, the toner save process can be separated from the parts or processes other than the background decoding unit 112, which is advantageous for simplifying hardware or software for realizing the document image reproduction processing means 100.

  Note that, as in the example shown in FIG. 1, when the foreground, mask, and background have different resolutions or image sizes, the composition processing unit 113 performs resolution conversion for matching the resolutions.

  Hereinafter, some embodiments regarding the background decoding unit 112 and the toner saving unit 101 will be described in detail. In each example described later, it is assumed that the background of the structured document is encoded by JPEG2000.

<Example 1>
FIG. 8 is a block diagram illustrating the configuration of the background decoding unit 112 and the toner save processing unit 101 according to the present embodiment. In FIG. 8, reference numerals 21, 22, 23, 24, 25, and 26 denote processing blocks with the same numbers in FIG. The luminance correction unit 201 and the luminance correction table 202 constitute the toner save processing unit 101.

  The luminance correction unit 201 is a unit that corrects the pixel value of the luminance component restored by the inverse wavelet transform of the processing block 25 when the toner save mode is designated. When the normal mode is designated, the luminance correction unit 201 performs no correction.

  FIG. 9 shows a processing flow of the luminance correction unit 201 when the toner save mode is designated. First, the correction value y corresponding to the luminance value x of the target pixel of the luminance component is read from the luminance correction table 202 (step 1), and the luminance value x of the target pixel is replaced with the correction value y (step 2). The target pixel is moved to the next pixel (step 4), and the process returns to step 1. The pixel value correction of the same luminance component is repeated while sequentially moving the target pixel, and when the processing has been completed up to the last pixel (step 3, Yes), the processing ends.

  The original RGB color system is obtained by performing DC reverse level shift and reverse color conversion in the processing block 26 on the data of the luminance component after correction and the color difference Cb and Cr components which have not been corrected. Background data (pixel value) is reproduced.

  FIG. 10 is a graph showing the relationship between the pre-correction pixel value and the post-correction pixel value (correction value) stored in the luminance correction table 202. The corrected pixel value is corrected to the high luminance side in the entire area of the pixel value before correction, but the correction degree (α) for the small pixel value (a) before correction is larger than the large pixel value (b) before correction. The correction characteristic is larger than the correction degree (β), that is, α> β. By correcting the pixel value of the luminance component using the luminance correction table 202 having such correction characteristics, the background data after the DC reverse level shift and the color reverse conversion are performed by the processing block 26 is as shown in FIG. Therefore, the overall brightness is high and the amplitude of the brightness is small, resulting in a bright and pale (thin) image. Therefore, the pattern portion of the synthesized document image data becomes a bright and light image. Such an image requires less color material consumption during printing.

  A specific example is shown in FIG. In the case of a structured document code composed of foreground, mask, and background as shown in the upper part of FIG. 12, in the normal mode, document image data having a dark pattern portion as shown in the upper right part of FIG. 12 is reproduced.

  On the other hand, in the toner save mode, the luminance correction as described above is performed on the background. As a result, the background is a bright and light image as shown in the lower part of FIG. Document image data with a light and light portion is reproduced. Such document image data requires less color material consumption in the image forming unit 104 during printing than document image data in the normal mode. Even in the toner save mode, no special correction is applied to the mask and foreground, so that characters in the printed document image do not become unclear and the character color does not become unnatural. Moreover, although the pattern portion is a bright and light image, the contents can be identified.

As is apparent from the above description, this embodiment is an embodiment of the invention according to claim 1 .

<Example 2>
FIG. 13 is a block diagram illustrating the configuration of the background decoding unit 112 and the toner save processing unit 101 according to the present embodiment. In FIG. 13, reference numerals 21, 22, 23, 24, 25, and 26 denote processing blocks with the same numbers in FIG. The coefficient correction unit 301 and the luminance coefficient correction table 302 constitute the toner save processing unit 101.

  The coefficient correction unit 301 corrects the coefficient of the LL subband, which is the low frequency subband of the luminance component after dequantization (including denormalization) by the processing block 24 when the toner save mode is designated. It is a means to perform. In the normal mode, the coefficient correction unit 301 does not perform any correction.

  FIG. 14 shows a processing flow of the coefficient correction unit 301 in the toner save mode. That is, if the attention coefficient of the luminance component is an LL subband coefficient (step 11, Yes), the correction value y corresponding to the attention coefficient value x is read from the luminance coefficient correction table 302 (step 12), and the attention coefficient value x Is replaced with the correction value y (step 13). The attention coefficient is moved to the next coefficient (step 15), and the process returns to step 11. The same correction of the LL subband coefficient is repeated while sequentially moving the attention coefficient, and when there are no remaining luminance component coefficients (step 14, Yes), the processing ends.

  The inverse wavelet transform is executed for each tile in the processing block 25 on the luminance component in which the LL subband coefficient is corrected in this way and the coefficient of each of the Cb and Cr components which are not corrected, and then in the processing block 26, the DC By performing reverse level shift and reverse color conversion, the original RGB color system background data is reproduced.

  FIG. 15 is a graph showing the relationship between the coefficient value before correction and the coefficient value after correction (correction value) stored in the coefficient correction table 302. Correction is made to the high luminance side in the entire coefficient value, but the correction degree (C) for the small coefficient value (c) is larger than the correction degree (D) for the large coefficient value (d), that is, a relationship of C> D. It is a correction characteristic.

  In order to correct the coefficient values of the LL subbands of the above-described luminance component using the luminance coefficient correction table 302 having such correction characteristics, the processing block 25 performs inverse wavelet transform, and the processing block 26 performs DC inverse level shift and color. The background reproduced by performing the inverse transformation is an overall bright and pale (thin) image. Therefore, since the pattern portion of the document image data to be synthesized becomes a bright and light image, consumption of the coloring material at the time of printing is reduced as described in the first embodiment. Since the subband coefficients other than the LL subband coefficient of the background are not corrected, the outline of the pattern of the document image is considerably preserved, and the contents of the pattern part can be sufficiently read. Since the foreground and the mask are not corrected, characters and character colors are normally reproduced.

  As shown in FIG. 16, when the number of decomposition levels (number of hierarchies) of wavelet transform is 2, the number of LL (2LL) subband coefficients is as small as 1/16 of the total coefficients (total number of pixels). Compared to the case where all pixels of the luminance component after inverse wavelet transform are corrected as in the first embodiment, the amount of processing for correction is greatly reduced, which is advantageous for speeding up the processing. This advantage becomes more prominent as the number of decomposition levels increases. That is, if the number of decomposition levels is N, the number of LL subband coefficients is 1 / 2N to the 2Nth power of all coefficients. For example, when N = 3, the number of LL subband coefficients is 1 / 64th of all the coefficients, so that the correction process can be further speeded up.

As is apparent from the above description, this embodiment is an embodiment of the invention according to claim 2 .

In other words, it is determined in step 11 whether the decomposition level (hierarchy) to which the attention coefficient belongs is equal to or higher than a predetermined level, and the coefficient of each subband having a decomposition level equal to or higher than the predetermined decomposition level (hierarchy lower than the predetermined hierarchy). Correction may be performed in steps 12 and 13. For example, when the number of decomposition levels is 3, the coefficients of the LL subband, the LH subband, the HL subband, and the HH subband at the decomposition level 3 (the lowest hierarchy) may be corrected. However, the coefficient correction value for each subband coefficient needs to be stored in the luminance correction table 302. It is clear from the above description that even with such a configuration, it is possible to reproduce document image data that can save color material consumption during printing. Such an aspect corresponds to an embodiment of the invention according to claim 3 .

<Example 3>
FIG. 17 is a block diagram illustrating the configuration of the background decoding unit 112 and the toner save processing unit 101 according to the present embodiment. In FIG. 17, reference numerals 21, 22, 23, 24, 25, and 26 denote processing blocks with the same numbers in FIG. The coefficient correction unit 401, the luminance coefficient correction table 402, and the color difference coefficient correction table 403 constitute the toner save processing unit 101.

  The coefficient correction unit 401 is a low-frequency subband of each component of luminance Y and color differences Cb and Cr after inverse quantization (including inverse normalization) in the processing block 24 when the toner save mode is designated. Although it is a means for correcting the coefficients of the LL subband, no correction is performed when the normal mode is designated.

  FIG. 18 shows a processing flow of the coefficient correction unit 401 in the toner save mode. That is, if the attention coefficient is an LL subband coefficient (step 21, Yes), the correction value y corresponding to the value x of the attention coefficient is obtained, and if the attention coefficient is a luminance component, the attention coefficient is obtained from the luminance coefficient correction table 402. If the coefficient is a color difference component, it is read from the color difference coefficient correction table 403 (step 22), and the target coefficient value x is replaced with the correction value y (step 23). The attention coefficient is moved to the next coefficient (step 25), and the process returns to step 21. The correction of the coefficient of the LL subband of each component is repeated while sequentially moving the attention coefficient. When there are no remaining coefficients (step 24, Yes), the process is terminated.

  The inverse wavelet transform is executed for each tile in the processing block 25 on the coefficient of each component after correcting the coefficients of the LL subband in this manner, and then the DC inverse level shift and the inverse color conversion are performed in the processing block 26. As a result, the background data of the original RGB color system is reproduced.

  The luminance coefficient correction table 402 is a table having the same contents as the luminance coefficient correction table 302 of the second embodiment, and the relationship between the stored pre-correction coefficient value and the post-correction coefficient value is expressed as shown in FIG. . By correcting the LL subband coefficient of the above-described luminance component using the coefficient correction table 402 of such correction characteristics, the luminance component after the inverse wavelet transform becomes an overall bright and light (thin) image.

  FIG. 19 is a graph showing the relationship between the coefficient value before correction stored in the color difference coefficient correction table 403 and the coefficient value after correction (correction value). As shown in the figure, correction is performed so that the color difference is compressed over the entire coefficient value, but the correction value for the coefficient value (f) having a large absolute value before correction is larger than the correction degree (E) for the coefficient value (e) having a small absolute value. The correction degree (F) is large, that is, the correction characteristic has a relationship of F> E. Since correction of the LL subband coefficient of the color difference component described above is performed using the coefficient correction table 403 having such correction characteristics, the color difference component after the inverse wavelet transform becomes an image with less color tone in which the color difference is compressed.

  Therefore, since the entire pattern portion of the document image data to be synthesized is a light image with a light color and a weak color, consumption of the coloring material during printing is reduced as described in the first embodiment. Since the coefficients of the subbands other than the LL subband of the background are not corrected, the outline of the picture part of the document image is considerably preserved, so that the contents of the picture part can be identified. Since the foreground and the mask are not corrected, characters and character colors are normally reproduced.

  As described in connection with the second embodiment, when the number of decomposition levels as shown in FIG. 16 is 2, the number of LL subband coefficients is as small as 1/16 of the total coefficients (total number of pixels). Even if all the components of luminance and color difference are to be corrected, the processing amount for correction is greatly reduced and the processing speed is high compared with the case of correcting all the pixels of the luminance component after inverse wavelet transform as in the first embodiment. It is advantageous to make. As described in connection with the second embodiment, this advantage is more remarkable as the number of decomposition is larger.

As is apparent from the above description, this embodiment is an embodiment of the invention according to claim 6 .

As described in the second embodiment, it is determined in step 21 whether the decomposition level to which the attention coefficient belongs is equal to or higher than a predetermined level, and the decomposition level is equal to or higher than a predetermined decomposition level (in a hierarchy lower than a predetermined hierarchy). ) Each subband coefficient may be corrected in steps 22 and 23. For example, when the number of decomposition levels is 3, the coefficients of the LL subband, the LH subband, the HL subband, and the HH subband at the decomposition level 3 (the lowest hierarchy) may be corrected. However, the coefficient correction value for each subband needs to be stored in the coefficient correction tables 402 and 403. Even with such a configuration, it is possible to reproduce document image data that can save color material consumption during printing. This aspect corresponds to an embodiment of the invention according to claim 7 .

<Example 4>
FIG. 20 is a block diagram illustrating the configuration of the background decoding unit 112 and the toner save processing unit 101 according to the present embodiment. In FIG. 20, 21, 22, 23, 24, 25, and 26 are processing blocks with the same numbers in FIG. However, the normalized denominator value used for denormalization is corrected in the processing block 24 in the toner save mode.

  In addition to the standard normalization denominator table 501, the brightness normalization denominator correction table 502 is provided in association with the denormalization process in the processing block 24. The standard normalized denominator table 501 stores standard normalized denominator values (the same as those used in normalization at the time of encoding). The normalized luminance denominator correction table 502 stores normalized denominator correction values for the LL subband coefficients of the luminance component. When the toner save mode is designated, the normalized denominator correction value stored in the normalized luminance denominator correction table 502 is used to denormalize the LL subband coefficient of the luminance component. Toner save processing is performed on the background. That is, in this embodiment, the toner save processing unit 101 is realized by the processing block 24 (its denormalization function) and the luminance normalization denominator correction table 503.

  The processing block 24 performs inverse quantization and inverse normalization, and FIG. 21 shows a process flow of inverse normalization when the toner save mode is designated. The denormalization process is performed on all coefficients of all components. When the normal mode in which toner saving is not performed is designated, the denormalization processing is performed in a processing loop including step 31, step 35, step 36, and step 37.

  Refer to FIG. A standard normalized denominator value Q corresponding to the attention coefficient is acquired from the standard normalized denominator table 501 (step 31). If the attention coefficient is not the coefficient of the LL subband which is the low frequency subband of the luminance component (step 32, No), the attention coefficient is denormalized by multiplying the attention coefficient value x by the standard normalized denominator value Q (step 35). ).

  If the attention coefficient is the coefficient of the LL subband of the luminance component (step 32, Yes), the normalized denominator correction value Q ′ corresponding to the attention coefficient value x is read from the luminance normalized denominator correction table 502 (step 33). The normalized denominator value Q is replaced with the normalized denominator correction value Q ′ (step 34), and the attention coefficient is denormalized by multiplying the normalized denominator value Q after the replacement (correction) by the attention coefficient value x (step 35). .

  The attention coefficient is moved to the next coefficient (step 37), and the process returns to step 31. The same denormalization process is repeated while sequentially moving the attention coefficient, and when all the coefficients of all components have been processed (step 36, Yes), the process ends.

  The processing block 24 performs inverse wavelet transform for each tile in the processing block 25 on the coefficients of each component after processing, and then performs DC inverse level shift and inverse color conversion in the processing block 26 to thereby restore the original RGB The color system background data is reproduced.

  FIG. 22 is a graph showing the relationship between the normalized denominator correction value stored in the luminance normalized denominator correction table 502 and the value of the LL subband coefficient of the luminance component. As shown in the figure, the normalized denominator correction value is corrected so as to be larger than the standard normalized denominator value (standard value) over the entire coefficient value, but the correction degree (C) for a small coefficient value (c) Is larger than the degree of correction (D) for a large coefficient value (d), that is, the correction characteristic has a relationship of C> D.

  Since the normalized denominator correction value of such a correction characteristic is used for the denormalization of the LL subband coefficient of the luminance component described above, the background after the DC inverse level shift and the color inverse transform is generally bright and light (light). ) It becomes an image. Therefore, the pattern portion of the document image data to be synthesized becomes a bright and light image, so that consumption of color materials during printing is reduced. Since the coefficients of subbands other than the LL subband of the background are not corrected, the outline of the picture part of the document image is considerably preserved, and the contents of the picture part can be sufficiently identified. Since the foreground and the mask are not corrected, characters and character colors are normally reproduced.

  As described in connection with the second embodiment, as shown in FIG. 16, when the number of decomposition levels = 2, the number of coefficients of the LL subband is 16 minutes of the total coefficients (total number of pixels). Therefore, compared with the case where all the pixels of the luminance component after the inverse wavelet transform are corrected as in the first embodiment, the processing amount for correction is greatly reduced, which is advantageous for speeding up the processing. This advantage is more conspicuous as the number of decomposition is larger. For example, when N = 3, the number of LL subband coefficients is 1 / 64th of all coefficients, so that the correction process is further speeded up.

As is apparent from the above description, this embodiment is an embodiment of the invention according to claim 4 .

In other words, in step 32, it is determined whether or not the decomposition level to which the attention coefficient belongs is equal to or higher than a predetermined level, and the coefficient of each subband (in the hierarchy below the predetermined hierarchy) of the decomposition above the predetermined decomposition level of the luminance component is determined. Steps 33 and 34 may be executed. For example, when the number of decomposition levels = 3, steps 33 and 34 are executed for the coefficients of the LL subband, LH subband, HL subband, and HH subband of the luminance component decomposition level 3 (lowest hierarchy). It can also be. However, the normalized denominator correction value for each subband needs to be stored in the luminance normalized denominator correction table 502. It is clear from the above description that even with such a configuration, it is possible to reproduce document image data that can save color material consumption during printing. This aspect corresponds to an embodiment according to the fifth aspect.

<Example 5>
FIG. 23 is a block diagram illustrating the configuration of the background decoding unit 112 and the toner save processing unit 101 according to the present embodiment. In FIG. 23, 21, 22, 23, 24, 25, and 26 are processing blocks with the same numbers in FIG. However, the normalized denominator value used for the denormalization in the processing block 24 in the toner save mode is corrected.

  In relation to the inverse normalization process in the processing block 24, in addition to the standard normalization denominator table 601, a luminance normalization denominator correction table 602 and a color difference normalization denominator correction table 603 are provided. The standard normalized denominator table 601 stores standard normalized denominator values (the same as those used in normalization at the time of encoding). The normalized luminance denominator correction table 602 stores normalized denominator correction values for the coefficients of the LL subbands of the luminance component. The color difference normalized denominator correction table 603 stores normalized denominator correction values for the coefficients of the LL subbands of the color difference Cb and Cr components.

  In the toner save mode, the normalized denominator correction value stored in the luminance normalization denominator correction table 602 is used for inverse normalization with respect to the coefficient of the LL subband, which is the low frequency subband of the luminance component, and the color difference component is reduced. By using the normalized denominator correction value stored in the color difference normalized denominator correction table 603 for inverse normalization with respect to the coefficients of the LL subband which is the frequency subband, the background image is subjected to toner save processing. That is, in this embodiment, the toner save processing unit 101 is realized by the processing block 24 (its denormalization function), the luminance normalization denominator correction table 602, and the color difference normalization denominator correction table 603.

  In the processing block 24, inverse quantization and inverse normalization processes are performed. FIG. 24 shows a process flow of inverse normalization in the toner save mode. The denormalization process is performed on all coefficients of all components. When the normal mode in which toner saving is not performed is designated, the denormalization processing is performed in a processing loop including step 41, step 45, step 46, and step 47.

  Refer to FIG. A standard normalized denominator value Q corresponding to the attention coefficient is acquired from the standard normalized denominator table 501 (step 41). If the attention coefficient is not the LL subband coefficient (step 42, No), the attention coefficient is denormalized by multiplying the attention coefficient value x by the standard normalized denominator value Q (step 45).

  If the attention coefficient is an LL subband coefficient (step 42, Yes), if the attention coefficient is a luminance component, from the luminance normalization denominator correction table 602, and if the attention coefficient is a color difference component, from the color difference normalization denominator correction table 603. Then, the normalized denominator correction value Q ′ corresponding to the attention coefficient value x is read (step 43), the normalized denominator value Q acquired in step 41 is replaced with the normalized denominator correction value Q ′ (step 44), and after the replacement (correction) The attention coefficient is denormalized by multiplying the attention coefficient value x by the normalized denominator value Q (step 45).

  The attention coefficient is moved to the next coefficient (step 47), and the process returns to step 41. The same denormalization process is repeated while sequentially moving the attention coefficient, and when all the coefficients of all the components have been processed (step 46, Yes), the process ends.

  The processing block 24 performs inverse wavelet transform for each tile in the processing block 25 on the coefficients of each component after processing, and then performs DC inverse level shift and inverse color conversion in the processing block 26 to thereby restore the original RGB The color system background data is reproduced.

  The luminance normalized denominator correction table 602 is a table having the same contents as the luminance normalized denominator correction table 502 of all the embodiments 4, and the relationship between the stored coefficient values and the normalized denominator correction values is as shown in FIG. It is expressed in Since the normalized denominator correction value of such correction characteristics is used for denormalization of the LL subband coefficient of the above-described luminance component, the luminance component obtained by inverse wavelet transform in the processing block 25 is an overall bright and light (thin) image. It becomes.

  FIG. 25 is a graph showing the relationship between the coefficient values stored in the color difference normalized denominator correction table 603 and the normalized denominator correction values. As shown in the figure, the normalized denominator correction value is corrected to be smaller than the standard normalized denominator value (standard value) over the entire coefficient value, but the correction degree (E) for the coefficient value (e) having a small absolute value. The correction degree (F) for the coefficient value (f) having a larger absolute value is large, that is, the correction characteristic has a relationship of D <F. Since such a normalized denominator correction value is used for denormalization of the LL subband coefficient of the color difference component described above, the color difference is compressed. Therefore, the color difference component subjected to the inverse wavelet transform by the processing block 25 becomes an image having a weak color.

  From the above, the background after the DC reverse level shift and color reverse conversion by the processing block 26 is a light image with a bright overall color and a weak color. Accordingly, the pattern portion of the document image data to be synthesized is a light and light-colored light image, so that the consumption of color materials during printing is reduced. Since the coefficients of the subbands other than the LL subband of the background are not corrected, the outline in the pattern of the document image is considerably preserved, and the contents of the pattern part can be sufficiently identified. Since the foreground and the mask are not corrected, characters and character colors are normally reproduced.

  As described in connection with the second embodiment, as shown in FIG. 16, when the number of decomposition levels = 2, the number of LL subband coefficients is 1/16 of the total coefficients (total number of pixels). Therefore, compared with the case where all pixels of the luminance component after inverse wavelet transform are corrected as in the first embodiment, the amount of processing for correction is greatly reduced, which is advantageous for speeding up the processing. This advantage is more conspicuous as the number of decomposition is larger. For example, when N = 3, the number of LL subband coefficients is 1 / 64th of all coefficients, so that the correction process is further speeded up.

As is apparent from the above description, this embodiment is an embodiment of the invention according to claim 8 .

Also, in step 42, it is determined whether the decomposition level to which the attention coefficient belongs is equal to or higher than a predetermined level, and steps 43 and 44 are performed for the coefficients of the subbands (in the hierarchy lower than the predetermined hierarchy) of the decomposition level equal to or higher than the predetermined decomposition level. You may make it perform. For example, when the number of decomposition levels is 3, steps 43 and 44 are executed for the coefficients of the LL subband, the LH subband, the HL subband, and the HH subband of the decomposition level 3 (the lowest hierarchy). You can also. However, it is necessary to store the normalized denominator correction value for each subband in the luminance normalized denominator correction table 602 and the color difference normalized denominator correction table 603. It is clear from the above description that even with such a configuration, it is possible to reproduce document image data that can save color material consumption during printing. This aspect corresponds to an embodiment of the invention according to claim 9 .

<Other embodiments>
Although not shown, it is also possible to adopt a configuration in which the first, second, third, fourth, and fifth embodiments are combined. For example, the background of the toner save processing means by pixel value correction as in the first embodiment and the toner save processing means by coefficient value correction as in the second embodiment (or a modification thereof) or the third embodiment (or a modification thereof). A configuration in which one of the toner save processing means is selected and operated is also possible in the decoding unit 112, and this aspect is also included in this embodiment. Further, for example, a toner save processing means by pixel value correction as in the first embodiment, and a toner save processing means by denormalization correction as in the fourth embodiment (or its modification) or the fifth embodiment (or its modification). Can be provided in the background decoding unit 112, and one of the toner save processing units can be selected and operated. Such an embodiment is also included in this embodiment. The above corresponds to the description of the inventions according to claims 10 and 11 .

[Example of printer configuration]
FIG. 26 shows an example of the hardware configuration of the printer according to the present invention. In FIG. 26, 701 is a CPU, 702 is a ROM storing a program for control and processing, 703 is a RAM used as a working storage area of the CPU 701 and a storage area of an execution program, 704 is a decoding unit, 705 is It is an interface unit for communication with an external personal computer PC. An image output unit 705 includes an image processing unit 707 (corresponding to the image processing unit 103 in FIG. 6) and an image forming unit 708 (corresponding to the image forming unit 104 in FIG. 6).

  The decoding unit 704 includes the foreground decoding unit 110, the mask decoding unit 111, and the background decoding unit 112 (including the toner save processing unit 101) in FIG. The function of the composition processing unit 113 in FIG. 7 is realized by program processing of the CPU 701. However, the function of the composition processing unit 113 can be included in the image processing unit 707.

  The structured document code transferred from the personal computer PC is taken in through the interface unit 705 and temporarily stored in a specific area of the RAM 703. Specification of normal mode or toner save mode is also given from the personal computer PC. When the toner save mode is designated, the CPU 701 enables the toner save processing means of the background decoding unit in the decoding unit 704, and the toner described in the first, second, third, fourth, or fifth or the modified examples. Save processing is executed.

  In response to a command from the CPU 701, the code of the structured document on the RAM 703 is transferred to the decoding unit 704, and the foreground, mask, and background are decoded. At this time, if the toner save mode is designated, the background decoding unit sets the background. A toner save process is performed. The decoded foreground, mask, and background data are transferred to the RAM 703. Processing for synthesizing the document image data from the foreground, mask, and background data is executed by the program processing of the CPU 701, and the document image data is reproduced on the RAM 703. This document image data is transferred to the image processing unit 707 and processed by a command from the CPU 701, and a print signal is output to the image forming unit 708, whereby the document image data reproduced from the structured document code is printed. The When the toner save mode is designated, the toner save process as described above is performed on the background, so toner save printing is performed, and the color material consumption of the image forming unit 708 is suppressed.

Note that the document image reproduction processing unit including the function of the decryption unit 704 can be realized by the program processing of the CPU 701, and such an aspect is also included in the present embodiment. A program therefor corresponds to an embodiment of the invention according to claim 13 .

[Form in which the document image reproduction processing unit is mounted on the computer side]
Instead of mounting the document image reproduction processing unit on the printer (image output apparatus) side, it is also possible to mount it as software (application, printer driver, etc.) on the computer side such as a personal computer connected to the printer. FIG. 27 is a flowchart for explaining the embodiment.

  In FIG. 27, a foreground code decoding process of a structured document (step 51), a mask code decoding process (step 52), and a background code decoding process including a toner save process (step 53) by a printer driver on the computer side such as a personal computer. Then, in accordance with the decoded mask, a process for synthesizing the decoded foreground and background (step 54) is executed to reproduce the document image data, and this document image data is transferred to the printer via the interface cable or the LAN cable. On the printer side, the image processing unit executes processing for converting document image data transferred from the personal computer into CMYK signals (step 55), gamma correction processing (step 56), and halftone processing (step 57) to generate a print signal. Then, this is given to the image forming unit to print the document image.

A program that causes a computer such as a personal computer to function as a document image generation processing unit, such as the printer driver, corresponds to an embodiment of the invention according to claim 13 . A computer-readable information recording medium such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor storage element on which such a program is recorded corresponds to an embodiment of the invention according to claim 14 .

[Configuration example of copier]
FIG. 28 shows an example of the hardware configuration of the copying machine according to the present invention. 28, reference numeral 801 denotes a CPU, 802 denotes a ROM storing a program for control and processing, and 803 denotes a RAM used as a working storage area of the CPU 801, a storage area of an execution program, and the like. Reference numeral 804 denotes an image input unit that optically reads a document original and inputs document image data (raster data). Reference numeral 805 denotes a structured document composed of foreground, mask, and background from the document image data input from the image input unit 804. Reference numeral 806 denotes an image storage unit such as a hard disk device for storing structured document codes and the like. Reference numeral 807 denotes a decoding unit, and 808 denotes an image output unit, which includes an image processing unit 809 corresponding to the image processing unit 103 in FIG. 6 and an image forming unit 910 corresponding to the image forming unit 104 in FIG. Reference numeral 811 denotes an operation unit for the user to input various instructions.

  The decoding unit 807 includes the foreground decoding unit 110, the mask decoding unit 111, and the background decoding unit 112 (including the toner save processing unit 101) in FIG. The function of the composition processing unit 113 in FIG. 7 is realized by program processing of the CPU 801. However, the function of the composition processing unit 113 can be included in the image processing unit 809, and such an aspect is also included in the present embodiment.

  The user can specify the structured document code stored in the image storage unit 806 using the operation unit 811 and instruct the printing thereof. At this time, the user can also specify a toner save mode and a normal mode in which toner save is not performed.

  When a print instruction is input, the structured document code designated by the image storage unit 806 is transferred to the RAM 803 by an instruction from the CPU 801. In accordance with a command from the CPU 801, the structured document code on the RAM 803 is transferred to the decoding unit 807, and the foreground, the mask, and the background are decoded. When the toner save mode is designated, the CPU 801 enables the toner save processing means in the background decoding unit, so that the toner save process is performed on the background. The decoded foreground, mask and background data are transferred to the RAM 803. Processing for synthesizing document image data from the foreground, mask, and background data is executed by the program processing of the CPU 801, and the document image data is reproduced on the RAM 803. This document image data is transferred to the image processing unit 809 and processed by an instruction from the CPU 801, and a print signal is output to the image forming unit 810, whereby the document image data reproduced from the structured document code is printed. The When the toner save mode is designated, the toner save process as described above is performed on the background, so that the color material consumption of the image forming unit 810 can be suppressed.

  The background decoding unit in the decoding unit 807 may be provided with a plurality of toner save processing units as described in [Other Embodiments] so that the user can select the toner save processing unit. In this case, it would be convenient for the user to be able to confirm in advance what kind of printing result will be obtained when the selected toner save processing means is applied.

  For this purpose, preview image data for showing an example of printing when the toner save processing unit is applied is stored in the image storage unit 806, and the toner save processing unit selected by the user is stored in the toner save processing unit. The corresponding preview image data can be displayed and the user can be confirmed.

For example, when the user presses the “toner save” button 915 of the operation unit 811 as shown in FIG. 29 and designates the toner save mode, the selection screen 912 as shown in FIG. 29 is displayed on the display unit 911 of the operation unit 811. Is displayed, and the user selects the “high speed” button 913 or the “high accuracy” button 914. Here, the “high speed” button 913 is a software button for specifying the toner save processing means of the second embodiment, for example, and the “high accuracy” button 914 is a software button for specifying the toner save processing means of the first embodiment, for example. Button. For example, when the “high speed” button 913 is pressed, preview image data corresponding to the toner save processing unit of the second embodiment is read from the image storage device 806 and displayed as a preview image 917 as shown in FIG. Display on the screen and ask the user to confirm. The user can confirm the selection of the “fast” button 913 by pressing the “confirm” button 921. If the user wants to make a selection again, the user can return to the state of the selection screen of FIG. 29 by pressing a “Cancel” button 922 and make a selection again. Processing related to such selection can be executed by program processing of the CPU 801. The above is the description of one embodiment of the invention according to claim 12 .

[Others]
In the above description, the background code is a JPEG2000 code, but is not limited to this. For example, if the code is encoded for each component of luminance and color difference, toner saving processing by luminance correction similar to that in the first embodiment is possible. If the code is encoded by an encoding method that performs subband division, toner save processing by coefficient correction similar to that in the second or third embodiment can be performed. As long as the code is encoded by an encoding method that performs subband division and normalizes coefficients, toner saving processing by normalization denominator correction similar to that in the fourth or fifth embodiment is possible.

It is a schematic diagram which shows the example of a structured document and its code | symbol. It is a block diagram for demonstrating a JPEG2000 encoding algorithm. It is a figure which shows the example of a subband division | segmentation by two-dimensional wavelet transformation. It is explanatory drawing of a tile, a subband, a precinct, and a code block. It is a block diagram for demonstrating a JPEG2000 decoding algorithm. It is a block diagram for demonstrating embodiment of this invention. It is a block diagram of a document image reproduction processing unit. FIG. 3 is a block diagram illustrating a first embodiment of a background decoding unit and toner save processing means. It is a flowchart which shows the processing content of a brightness correction part. It is a graph for demonstrating a brightness correction table. It is a figure for demonstrating the effect of a toner save process. It is a figure which shows the example of a structured document, and the result of a toner save process. FIG. 10 is a block diagram illustrating a second embodiment of a background decoding unit and toner save processing means. It is a flowchart which shows the processing content of a coefficient correction | amendment part. It is a graph for demonstrating the coefficient correction table for brightness | luminances. It is a figure for demonstrating the ratio with respect to the total coefficient (total number of pixels) of a LL subband coefficient. FIG. 10 is a block diagram illustrating a third embodiment of a background decoding unit and toner save processing means. It is a flowchart which shows the processing content of a coefficient correction | amendment part. It is a graph for demonstrating the coefficient correction table for color differences. FIG. 10 is a block diagram illustrating a fourth embodiment of a background decoding unit and toner save processing means. It is a flowchart of a denormalization process. It is a graph for demonstrating the normalization denominator correction table for brightness | luminances. FIG. 10 is a block diagram illustrating a fifth embodiment of a background decoding unit and toner save processing means. It is a flowchart of a denormalization process. It is a graph for demonstrating the normalization denominator correction table for color differences. 1 is a block diagram illustrating a configuration example of a printer according to the present invention. It is a flowchart for demonstrating the form which mounts a document image reproduction | regeneration processing part in the personal computer side. 1 is a block diagram illustrating a configuration example of a copying machine according to the present invention. It is explanatory drawing of an operation part. It is explanatory drawing of an operation part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Document image data 2 Foreground 3 Mask 4 Background 11 Processing block 12 for DC level shift and color conversion Processing block 13 for wavelet conversion Processing block 14 for quantization and normalization Processing for bit plane encoding Block 15 Processing block 16 for packet generation Processing block 21 for code formation Processing block 22 for code analysis Processing block 23 for packet division Processing block 24 for bit-plane decoding Inverse quantization and inverse normalization Processing block 25 for processing block 26 for inverse wavelet transform Processing block 100 for DC inverse level shift and inverse color conversion Document image reproduction processing unit 101 Toner save processing unit 102 Image output unit 103 Image processing unit 104 Image formation Unit 105 color conversion processing unit 106 Gamma correction unit 107 Halftone processing unit 110 Foreground decoding unit 111 Mask decoding unit 112 Background decoding unit 113 Composition processing unit 201 Brightness correction unit 202 Brightness correction table 301 Coefficient correction unit 302 Coefficient correction table for luminance 401 Coefficient correction unit 402 Coefficient for luminance Correction table 403 Color difference coefficient correction table 501 Standard normalization denominator table 502 Normalization denominator correction table 601 Standard normalization denominator table 602 Normalization denominator correction table 603 Normalization denominator correction table for color difference

Claims (14)

Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code encoded for each component of luminance and color difference.
  The toner saving process is a process of correcting the pixel value of the luminance component in the decoding process of the background code, and correcting the pixel value having a large degree of correction for a small pixel value in the correction process. An image output system characterized by being larger than the degree. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code divided into subbands for each component of luminance and color difference.
  The toner save process is a process of correcting the coefficient value of the low frequency subband of the luminance component to the side in the decoding process of the background code, and the correction degree for the small coefficient value is large in the correction process. An image output system characterized in that the degree of correction is larger than the coefficient value. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code that is divided into subbands hierarchically for each component of luminance and color difference,
  The toner saving process is a process of correcting the coefficient value of the subband in the hierarchy below the predetermined hierarchy of the luminance component in the decoding process of the background code, and correcting the small coefficient value in the correction process An image output system characterized in that the degree of correction is larger than the degree of correction with respect to a large coefficient value. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code in which the subband is divided for each component of luminance and color difference, and the coefficient value of each subband is normalized.
  The toner save process is a process of correcting the normalized denominator value used for denormalization of the coefficient value of the low frequency subband of the luminance component to a side that increases from the standard value in the decoding process of the background code, An image output system characterized in that the degree of correction of a normalized denominator value used for denormalization with respect to a small coefficient value in the correction process is greater than the degree of correction of a normalized denominator value used for denormalization with respect to a large coefficient value . Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code in which subbands are hierarchically divided for each component of luminance and color difference, and the coefficient values of each subband are normalized,
  The toner save process is a process of correcting the normalized denominator value used for denormalization to the coefficient value of the subband in the hierarchy below the predetermined hierarchy of the luminance component to the side that increases from the standard value in the decoding process of the background code. In the correction process, the degree of correction of the normalized denominator value used for denormalization for a small coefficient value is larger than the degree of correction of a normalized denominator value used for denormalization for a large coefficient value. Image output system. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code divided into subbands for each component of luminance and color difference.
  The toner saving process includes a process of correcting the coefficient value of the low frequency subband of the luminance component to the side that increases the coefficient value in the decoding process of the background code, and the absolute value of the coefficient value of the low frequency subband of the color difference component is decreased. Processing to correct the
  In the process of correcting the coefficient value of the luminance component, the degree of correction for a small coefficient value is larger than the degree of correction for a large coefficient value,
  In the processing for correcting the coefficient value of the color difference component, the degree of correction for a coefficient value having a large absolute value is larger than the degree of correction for a coefficient value having a small absolute value. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code that is divided into subbands hierarchically for each component of luminance and color difference,
  In the process of decoding the background code, the toner saving process corrects the coefficient component of the subband in the hierarchy below the predetermined hierarchy of the luminance component, and corrects the subband in the hierarchy below the predetermined hierarchy of the color difference component. Compensating the coefficient value to the side that decreases the absolute value,
  In the process of correcting the coefficient value of the luminance component, the degree of correction for a small coefficient value is greater than the degree of correction for a large coefficient value,
  In the process of correcting the coefficient value of the color difference component, the degree of correction for a coefficient value having a large absolute value is larger than the degree of correction for a coefficient value having a small absolute value. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code in which the subband is divided for each component of luminance and color difference, and the coefficient value of each subband is normalized.
  The toner saving process includes a process of correcting the normalized denominator value used for denormalization of the coefficient component of the low frequency subband of the luminance component to a side that increases from the standard value in the decoding process of the background code, It consists of a process of correcting the normalized denominator value used for denormalization to the coefficient value of the low frequency subband to the side to decrease from the standard value,
  In the process of correcting the normalized denominator value used for the denormalization of the coefficient value of the luminance component, the degree of correction of the normalized denominator value used for the denormalization for the small coefficient value is used for the denormalization for the large coefficient value. Greater than the degree of correction of the normalized denominator value,
  In the process of correcting the normalized denominator value used for denormalizing the coefficient value of the color difference component, the degree of correction of the normalized denominator value used for denormalization with respect to the coefficient value having a large absolute value is a coefficient value having a small absolute value. An image output system characterized by being larger than the degree of correction of a normalized denominator value used for denormalization of. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code in which subbands are hierarchically divided for each component of luminance and color difference, and the coefficient values of each subband are normalized,
  The toner saving process is a process of correcting a normalized denominator value used for denormalization to a coefficient value of a subband in a hierarchy lower than a predetermined hierarchy of a luminance component to a side to increase from a standard value in a decoding process of a background code. , And a process of correcting the normalized denominator value used for denormalization for the subband coefficient values of the layer below the predetermined layer of the color difference component to the side of decreasing from the standard value,
  In the process of correcting the normalized denominator value used for the denormalization of the coefficient value of the luminance component, the degree of correction of the normalized denominator value used for the denormalization for the small coefficient value is used for the denormalization for the large coefficient value. Greater than the degree of correction of the normalized denominator value,
  In the process of correcting the normalized denominator value used for denormalizing the coefficient value of the color difference component, the degree of correction of the normalized denominator value used for denormalization with respect to the coefficient value having a large absolute value is a coefficient value having a small absolute value. An image output system characterized by being larger than the degree of correction of a normalized denominator value used for denormalization of. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Document image data reproduced by the document image reproduction processing means is printed on a medium using a color material.
Image output means for
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code divided into subbands for each component of luminance and color difference.
  A high-accuracy mode for performing the toner saving process on the pixel value of the luminance component in the decoding process of the background code;
  A high-speed mode for performing the toner save processing on the low-frequency subband coefficient value of the luminance component or the low-frequency subband coefficient value of the luminance component and the color difference component in the decoding process of the background code;
  An image output system, wherein the high accuracy mode or the high speed mode can be selected. Document image reproduction that decodes the foreground, mask, and background from the code of a structured document that consists of a pair of foreground, mask, and background, and reproduces the document image data by combining the decoded foreground and background according to the decoded mask Processing means;
  Image output means for printing document image data reproduced by the document image reproduction processing means on a medium using a color material;
  The document image reproduction processing unit performs a toner save process for making the document image data reproduced from the code of the structured document printable by the image output unit while suppressing color material consumption. Including toner save processing means applied to the background of the document;
  The background code of the structured document is a code that is divided into subbands hierarchically for each component of luminance and color difference,
  A high-accuracy mode for performing the toner saving process on the pixel value of the luminance component in the decoding process of the background code;
  In the process of decoding the background code, the toner saving process is performed on the coefficient values of subbands in a hierarchy below the predetermined hierarchy of the luminance component, or on the coefficient values of subbands in the hierarchy below the predetermined hierarchy of the luminance component and the chrominance component. With high-speed mode,
  An image output system, wherein the high accuracy mode or the high speed mode can be selected. The high-precision mode preview image is displayed when the high-precision mode is selected, and the high-speed mode preview image is displayed when the high-speed mode is selected. The image output system according to 10 or 11. A program that causes a computer to function as the document image reproduction processing unit according to claim 1. 10. A computer-readable information recording medium in which a program for causing a computer to function as the document image reproduction processing means according to claim 1 is recorded.

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