JP2011142391A - Image processing apparatus, image formation apparatus, image processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing technique capable of controlling data capacity of the whole of image data in accordance with a predetermined format generated by using a foreground code and a background code while keeping suitable image quality. <P>SOLUTION: A picture/character separating section 51 extracts a feature of an input image, and generates a selection image representing into which of a pixel representing a character or line, or a pixel representing a non-character the input image is classified on a pixel basis. A background/foreground generation section 52 generates a background and a foreground using the input image and the selection image. A compression section 53 encodes the selection image as a mask. A code capacity determination section 54 determines respective data capacity values of codes of the background and those of the foreground using the selection image so that the data capacity of a multilayer image becomes a target data capacity. A picture compression section 55 respectively encodes the background and the foreground to become the respectively determined data capacity values. A multilayer structuring section 56 generates a multilayer image by wrapping the codes of the mask, those of the background and those of the foreground. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, an image processing method, and a program.

  Conventionally, as shown in Patent Document 1, for example, an input image is separated based on features obtained from each area of the image, and then converted into a format, such as an image representing a character or a line, a photograph or a picture. There is a technique for converting an image representing a natural image and image data having a multi-layer structure having an image representing for each pixel which image is selected. According to this technique, it is possible to reduce the data capacity of image data while maintaining the edge of characters and maintaining a smooth image quality of a natural image area. There is a demand to control the data capacity of image data generated by such a technique.

  For example, in the mail transmission / reception system, the system speed is reduced when trying to send / receive large amounts of data, and it is prevented that other accounts cannot be used due to using up the disk capacity of the system. For this purpose, the upper limit of the data capacity of the data to be transmitted or received is often set. When trying to transmit data exceeding the upper limit of the data capacity, the processing usually fails on the transmission side. Also, when data with a data capacity exceeding the upper limit of the data capacity that can be received on the receiving side is transmitted, the processing is successful on the transmitting side, but the processing fails on the receiving side, so that the data is eventually delivered to the receiving side. Can not do.

  In such a background, it is desirable not only to send and receive e-mails but also to use image data to control the data capacity of image data generated by compression using a multilayer structure to a predetermined or specified data capacity. It is. For example, Patent Document 2 discloses a rate control technique for performing control so that a code is generated at a specified compression rate when an image is encoded and compressed by the JPEG2000 method. JPEG2000 has scalability of resolution and image quality, and the data capacity of the generated code can be kept within the target data capacity. With this technology, when encoding the foreground representing the character image and the background representing the image of a natural image such as a picture or photo in the multi-layer structure image data, the foreground code and the background code are respectively encoded. The target data capacity can be controlled.

However, in the technique of Patent Document 2, although the foreground code and the background code can be controlled to the target data capacity, respectively, the overall data capacity of the multi-layered image data is maintained while maintaining a suitable image quality. It was difficult to control the data capacity.

  The present invention has been made in view of the above, and reduces the overall data capacity of image data in accordance with a predetermined format generated using the foreground code and background code while maintaining a suitable image quality. An object is to provide a controllable image processing apparatus, an image forming apparatus, an image processing method, and a program.

  In order to solve the above-described problem and achieve the object, the present invention provides an image processing apparatus, an image input receiving unit that receives an input of an image, and a character or line that represents characters or lines based on the characteristics of the image. Generates a selected image that represents for each pixel whether it is classified as one pixel or a second pixel other than a character and a line, a first image that includes the first pixel, and a second image that includes the second pixel First generating means for encoding, the first encoding means for encoding the selected image to generate a code for the selected image, and encoding each of the first image and the second image for encoding the first image. And second encoding means for generating a code for the second image, and a code for the first image, a code for the second image, and a code for the selected image, to generate image data according to a predetermined format. An image processing apparatus comprising: a second generation unit; And determining means for determining at least one of the code data capacity of the first image and the code data capacity of the second image so that the data capacity of the image data is equal to or less than a predetermined data capacity. The second encoding means converts the first image and the second image so as to have the data capacity determined for at least one of the code of the first image and the code of the second image, respectively. Each of the codes is encoded to generate a code for the first image and a code for the second image.

  In addition, the present invention is an image processing apparatus, which is an image input receiving unit that receives an input of an image, and a first pixel that represents a character or a line, or a first pixel that represents something other than a character and a line, based on the characteristics of the image. A first generation unit that generates a selection image that indicates which of the two pixels is classified for each pixel, a first image that includes the first pixel, and a second image that includes the second pixel; And a first encoding means for generating a code for the selected image, and a second encoding means for encoding the first image and the second image, respectively, and generating a code for the first image and a code for the second image, respectively. An image processing apparatus comprising: an encoding unit; and a second generation unit that generates image data according to a predetermined format using the code of the first image, the code of the second image, and the code of the selected image. The data capacity of the image data is And determining means for determining at least one of the compression rate of the first image and the compression rate of the second image so that the data capacity is less than or equal to the data capacity of the first image, And encoding each of the first image and the second image so as to achieve the compression ratio determined for at least one of the second image and the second image, respectively. Each is generated.

  According to another aspect of the present invention, there is provided an image forming apparatus including the above-described image processing apparatus and an image forming unit that forms an image on a recording medium using the image data.

  In addition, the present invention is executed by an image processing apparatus including an image input reception unit, a first generation unit, a first encoding unit, a second encoding unit, a second generation unit, and a determination unit. An image processing method, wherein the image input receiving unit receives an image input, and the first generation unit is a first pixel representing a character or a line based on the characteristics of the image, or A first image that generates a selection image that represents, for each pixel, a second pixel that represents a pixel other than a character and a line, a first image that includes the first pixel, and a second image that includes the second pixel. A first encoding step in which the first encoding unit encodes the selected image to generate a code of the selected image; and the second encoding unit includes the first image and the second image. Are encoded, and the code of the first image and the first A second encoding step for generating an image code, and an image in accordance with a predetermined format, wherein the second generation means uses the code of the first image, the code of the second image, and the code of the selected image. A second generation step of generating data; and the determination means, so that the data capacity of the image data is equal to or less than a predetermined data capacity, and the data capacity of the code of the first image and the data of the code of the second image A determination step of determining at least one of the capacities, and the second encoding step has the data capacities determined for at least one of the code of the first image and the code of the second image, respectively. As described above, the first image and the second image are encoded to generate a code for the first image and a code for the second image, respectively.

  In addition, the present invention is executed by an image processing apparatus including an image input reception unit, a first generation unit, a first encoding unit, a second encoding unit, a second generation unit, and a determination unit. An image processing method, wherein the image input receiving unit receives an image input, and the first generation unit is a first pixel representing a character or a line based on the characteristics of the image, or A first image that generates a selection image that represents, for each pixel, a second pixel that represents a pixel other than a character and a line, a first image that includes the first pixel, and a second image that includes the second pixel. A first encoding step in which the first encoding unit encodes the selected image to generate a code of the selected image; and the second encoding unit includes the first image and the second image. Are encoded, and the code of the first image and the first A second encoding step for generating an image code, and an image in accordance with a predetermined format, wherein the second generation means uses the code of the first image, the code of the second image, and the code of the selected image. A second generation step of generating data, and the determining means includes a compression ratio of the first image and a compression ratio of the second image so that a data volume of the image data is equal to or less than a predetermined data volume. A determination step for determining at least one of the first image and the second encoding step so that the compression rate determined for at least one of the first image and the second image is the same. The second image and the second image are encoded to generate a code for the first image and a code for the second image, respectively.

  Moreover, this invention is a program for making a computer perform said method.

  According to the present invention, it is possible to control the entire data capacity of image data according to a predetermined format generated using a foreground code and a background code while maintaining a suitable image quality.

FIG. 1 is a diagram illustrating image data in a format of mixed star content (MRC) as a multi-layer structure. FIG. 2 is a diagram illustrating a functional configuration of the image processing apparatus 50 according to the first embodiment. FIG. 3 is a diagram illustrating a mask, a foreground, and a background. FIG. 4 is a diagram conceptually illustrating encoding of a mask, foreground, and background generated from an input image. FIG. 5 is a diagram conceptually illustrating the data capacity determined by the code capacity determination unit 54. FIG. 6 is a flowchart showing the procedure of the multilayer image generation process performed by the image processing apparatus 50. FIG. 7 is a diagram illustrating a functional configuration of the image processing apparatus 50 according to the second embodiment. FIG. 8 is a diagram illustrating a selected image and a corrected selected image when the foreground resolution is halved. FIG. 9 is a flowchart showing a procedure of multi-layer image generation processing performed by the image processing apparatus 50 according to the present embodiment. FIG. 10 is a diagram illustrating a functional configuration of the image processing apparatus 50 according to the third embodiment. FIG. 11 is a diagram illustrating a data configuration of the document type correspondence table 58. FIG. 12 is a diagram for explaining background hole filling.

  Exemplary embodiments of an image processing apparatus, an image forming apparatus, an image processing method, and a program according to the present invention are explained in detail below with reference to the accompanying drawings.

[First embodiment]
Here, the hardware configuration of the image processing apparatus according to the present embodiment will be described. The image processing apparatus according to the present embodiment includes a control unit such as a CPU (Central Processing Unit) that controls the entire apparatus, a ROM (Read Only Memory) that stores various data and various programs, a RAM (Random Access Memory), and the like. Equipped with a main storage, auxiliary storage such as HDD (Hard Disk Drive) and CD (Compact Disk) drives that store various data and programs, and a bus connecting them, using a normal computer Hardware configuration. In addition, the image processing apparatus includes a display unit that displays information, an operation input unit such as a keyboard and a mouse that accepts user instruction inputs, and a communication I / F (interface) that controls communication with an external device. Each is connected by radio. In addition, a scanner for reading an image is connected to the image processing apparatus. In such a hardware configuration, the image processing apparatus generates image data having a multilayer structure with an image read by the scanner as an input.

  Here, the image data having a multi-layer structure will be described. FIG. 1 is a diagram illustrating image data in a format of mixed star content (MRC) as a multi-layer structure. In MRC, a target image is separated into layers of a background, a foreground, and a mask. The foreground is an image representing a character or line, and the background is an image representing a natural image such as a pattern or a photograph other than the character or line. The mask is data that represents, for each pixel, whether a background or foreground pixel is selected for superposition when generating a multilayer image that is image data having a multilayer structure. The mask generally represents a binary value indicating whether the background or the foreground is selected. For example, the mask is generated such that the pixel for selecting the background is “0” and the pixel for selecting the foreground is “1”. Since the mask forms details such as characters in the image, it is preferably generated with the same resolution as the input image. Note that the MRC is not limited to the example of FIG. 1, and for example, there is a configuration in which the background is separated into a plurality of foregrounds including transmissive pixels superimposed on the background. This will be described using an example of 1.

  Next, various functions implemented in the image processing apparatus in the hardware configuration as described above will be described. FIG. 2 is a diagram illustrating a functional configuration of the image processing apparatus 50. The image processing apparatus 50 includes an image input receiving unit (not shown), a design / character separation unit 51, a background / foreground generation unit 52, a compression unit 53, a code capacity determination unit 54, a design compression unit 55, And a multi-layer structuring unit 56. These units are generated on a main storage unit such as a RAM when the CPU program is executed.

  The image input receiving unit receives an input of an image read by a scanner connected to the image processing device 50. The pattern / character separation unit 51 extracts features such as edge strength and brightness of an image using an image (referred to as an input image) received by the image input receiving unit. Normally, a character area where characters or lines appear in an image and a natural image area where a natural image such as a pattern or photo other than characters appears, the frequency of the edge or pixel sample is different. The pattern / character separating unit 51 extracts features necessary for separating the characters. Then, the pattern / character separating unit 51 uses the extracted features to classify the pixel into a pixel representing a character or a line or a pixel representing the other (referred to as a non-character), and a selected image representing each pixel to be classified. Is generated. In the selected image, the pixel value of the pixel representing the character or line is represented by “1”, and the pixel representing the non-character is represented by “1”. This selected image is encoded when the multi-layer image is generated, and is also used as a mask for each pixel indicating which of the background or foreground pixels is selected for superposition.

  The background / foreground generation unit 52 generates a background and foreground using the input image received by the image input reception unit and the selected image generated by the design / character separation unit 51. Specifically, the background / foreground generation unit 52 determines whether each pixel constituting the input image received by the image input reception unit is classified as the background or the foreground with reference to the selected image. . At this time, the background / foreground generation unit 52 determines that the pixel represented by the selected image is classified as a pixel representing a character or a line and classifies it as a pixel representing a non-character. It is determined that the pixel represented by the image is classified as a background. That is, in the input image, pixels representing characters or lines belong to the foreground, and pixels representing non-characters belong to the background. Then, the background / foreground generation unit 52 generates the background and the foreground using the image including the pixels determined to be classified as the foreground as the foreground and the image including the pixels determined to be classified as the background as the background.

  FIG. 3 is a diagram illustrating a mask, a foreground, and a background. In the figure, it is shown that the foreground represents a character and the background represents a natural image excluding the character. In addition, in the mask, pixels for selecting the foreground at the time of generating the multilayer image are represented in black, and pixels for selecting the background are represented in white.

  The compression unit 53 generates a mask code by encoding and compressing the selected image generated by the design / character separation unit 51 as a mask. If the mask is expressed in binary as described above, a binary image encoding method such as MMR, JBIG, JIBG2 may be used as the compression method. FIG. 4 is a diagram conceptually illustrating encoding of a mask, foreground, and background generated from an input image. In the figure, the mask is encoded by the MMR method, and the foreground and background are encoded by the JPEG2000 method, as will be described later.

  The code capacity determination unit 54 uses the selected image generated by the design / character separation unit 51 so that the image data according to a predetermined format becomes the target data capacity and the data capacity of the background code and the code of the foreground code. Determine the data capacity. The data capacity of the image data according to the predetermined format includes a data capacity necessary for describing the predetermined format, a data capacity of the mask code, a data capacity of the background code, and a data capacity of the foreground code. The value of the target data capacity is set based on, for example, the image quality setting designated by the user via the operation input unit. Specifically, for example, when high image quality is set, the first target data capacity is set, and when low image quality is set, the second target data capacity is smaller than the first target data capacity. Is set. The correspondence relationship between the image quality and the target data capacity is stored in advance in the auxiliary storage unit as a table. The code capacity determination unit 54 refers to the table and sets a target data capacity corresponding to the image quality. Then, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the set target data capacity, and the data capacity of the background code and the data capacity of the foreground code The foreground code data is calculated by multiplying the sum by the ratio of pixels represented by the selected image to be classified as pixels representing characters with respect to all pixels of the selected image. The capacity is calculated, and a value obtained by subtracting the data capacity of the foreground code from the target data capacity is set as the data capacity of the background code. The predetermined format is, for example, PDF (Portable Document Format). FIG. 5 is a diagram conceptually illustrating the data capacity determined by the code capacity determination unit 54. As shown in the figure, the data capacity obtained by removing the mask data capacity and the data capacity of the description in the PDF format from the target data capacity is assigned as the sum of the data capacity of the foreground code and the data capacity of the background code. . For this sum, selecting the foreground depends on the proportion of pixels represented in the mask and selecting the background depends on the proportion of pixels represented in the mask, and the foreground code data volume and background code Each data capacity is allocated.

  The pattern compressing unit 55 encodes and compresses the background and foreground generated by the background / foreground generating unit 52 so as to have the data capacity determined by the code capacity determining unit 54, respectively. And a foreground code. As a compression method, for example, a JPEG 2000 multi-value image encoding method may be used. JPEG2000 rate control technology may be used to control the code data capacity. The multi-layer structuring unit 56 wraps (synthesizes) the mask code generated by the compression unit 53 and the background code and foreground code generated by the picture compression unit 55 to generate image data according to a predetermined format. A multi-layer image is generated. For example, in PDF (Portable Document Format), multi-layer images are overlaid in the order of the background code and mask code as the background for layer superposition, and foreground selection is represented by the mask. The pixels of the foreground code are further superimposed, and the PDF description is a file showing the number of background, mask, and foreground pixels, and their respective filter formats.

  Next, the procedure of the multilayer image generation process performed by the image processing apparatus 50 according to the present embodiment will be described with reference to FIG. Here, it is assumed that an image (input image) is input by the scanner and the image quality of the image is designated via the operation input unit. The image processing apparatus 50 extracts features of an input image that has received an input, classifies the features into pixels representing characters or pixels representing non-characters, and binarizes each of the pixels to be classified. Is generated (step S1). The image processing device 50 encodes the selected image as a mask to generate a mask code (step S2). Further, the image processing apparatus 50 generates a background and a foreground using the input image and the selected image (step S3). Next, the image processing apparatus 50 sets a target data capacity corresponding to the image quality specified by the user, and subtracts the data capacity necessary for the description of the predetermined format and the data capacity of the mask code from the target data capacity. Then, the sum of the data capacity of the background code and the data capacity of the foreground code is calculated (step S4). Then, the image processing device 50 counts the total number of pixels (number of pixels) represented by the selected image to be classified as a pixel representing a character, and determines the ratio of the pixel to the total pixels of the selected image. The value obtained by multiplying the ratio by the sum of the data capacity of the background code and the data capacity of the foreground code is determined as the data capacity of the foreground code. The image processing apparatus 50 determines a value obtained by subtracting the data capacity of the foreground code from the sum of the data capacity of the background code and the data capacity of the foreground code as the data capacity of the background code (step S5). ). Then, the image processing apparatus 50 generates the foreground code and the background code by encoding and compressing the data so as to have the determined data capacities for the foreground and the background (step S6). Thereafter, the image processing apparatus 50 adds a description of the PDF to the mask code, the background code, and the foreground code and wraps them to generate a multilayer image (step S7).

  As described above, in order to keep the total capacity of the multilayer image generated as the image data of the multilayer structure within the target data capacity, it is classified as either a pixel representing a character or a line or a pixel representing a non-character. A data capacity to be allocated to each of the foreground code and the background code is determined based on the selected image represented for each pixel. As a result, when the area of characters existing in the input image is large, more data capacity can be allocated to the foreground than when the area of characters is small, and the data capacity of the foreground code and the background code data A data capacity suitable for the capacity can be calculated. As a result, it is possible to generate a multi-layer image with better image quality than when the foreground code data capacity and the background code data capacity are allotted regardless of the mask.

[Second Embodiment]
Next, a second embodiment of the image processing apparatus, the image forming apparatus, the image processing method, and the program will be described. In addition, about the part which is common in the above-mentioned 1st Embodiment, it demonstrates using the same code | symbol or abbreviate | omits description.

  In the present embodiment, a case will be described in which at least one of the foreground and background is converted. FIG. 7 is a diagram illustrating a functional configuration of the image processing apparatus 50 according to the present embodiment. The image processing apparatus 50 according to the present embodiment includes an image input receiving unit, a design / character separation unit 51, a background / foreground generation unit 52, a compression unit 53, a code capacity determination unit 54, and a design compression unit 55. In addition to the multi-layer structuring unit 56, a resolution converting unit 57 is provided. The resolution conversion unit 57 converts at least one of the foreground and background generated by the background / foreground generation unit 52 into a designated resolution. The resolution is specified by the user via the operation input unit, for example. The designation of the resolution may be performed by the value of the resolution itself or by the ratio of the resolution after conversion to the conversion before conversion (conversion rate such as 1/2 or 50%). However, in the present embodiment, the case where the resolution is reduced, that is, the resolution is converted at a rate smaller than 100%, is handled.

  The code capacity determination unit 54 uses the selected image generated by the picture / character separation unit 51 to use the data capacity necessary for describing a predetermined format, the data capacity of the mask code, the data quantity of the background code, and the foreground code. The data capacity of the background code and the data capacity of the foreground code are determined so that the total data capacity becomes the target data capacity. However, when the resolution of at least one of the background and the foreground is converted, the resolution is converted. A correction selection image corresponding to the resolution is generated for the person to be processed, and the data volume of the background code and the data volume of the foreground code are determined using the correction selection image. Specifically, for example, FIG. 8 will be described for a case where the foreground resolution is halved. In this case, since the ratio of the pixels in the selected image to the foreground pixels after resolution conversion is 1: (1/2 × 1/2), the four pixels in the selected image are 1 in the foreground. One pixel will correspond. For this reason, as illustrated on the left side of FIG. 8, in the selected image, a new pixel is formed with four pixels as one set. Then, if there is at least one pixel classified as a pixel representing a character or a line in this set, the code capacity determination unit 54 classifies the pixel as a new pixel representing a character or a line, and at least one character or line is included in the set. If there is no pixel classified as a pixel to be represented, a corrected selection image is generated that represents that each new pixel is classified as a new pixel representing a non-character. In other words, lowering the foreground reduces the number of pixels that are not selected as the foreground when generating a multi-layer image, so the proportion of pixels selected as the foreground is lower than when the foreground is not reduced in resolution. growing. Therefore, the code capacity determination unit 54 generates a correction selection image corresponding to the resolution conversion rate in order to increase the ratio of the data capacity of the foreground code according to this ratio. Then, the code capacity determination unit 54 uses the ratio of pixels representing characters or lines among all the pixels of the correction selection image to determine the data capacity of the background code and the data capacity of the foreground code. That is, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the set target data capacity, and the background code data capacity and the foreground code data capacity. And calculating the data capacity of the foreground code by multiplying the total by the ratio of pixels classified as pixels representing characters or lines out of all pixels of the corrected selected image, The data capacity of the code obtained by subtracting the data capacity of the foreground code from the target data capacity is set as the data capacity of the background code.

  When the background resolution is converted, the code capacity determination unit 54 generates a correction selection image for the background in the same manner as in the foreground, and the pixels representing non-characters among all the pixels of the correction selection image. Is used to determine the data capacity of the background code and the data capacity of the foreground code. That is, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the set target data capacity, and the background code data capacity and the foreground code data capacity. And calculating the data capacity of the background code by multiplying the total by the ratio of the pixels classified as pixels representing non-characters among all the pixels of the corrected selection image, A value obtained by subtracting the data capacity of the background code from the target data capacity is set as the data capacity of the foreground code. When converting both the foreground and background resolutions, the code capacity determination unit 54 generates a correction selection image for the foreground and a correction selection image for the background, respectively. Alternatively, the ratio of pixels representing a line (referred to as a first ratio) and the ratio of pixels representing non-characters (referred to as a second ratio) among all the pixels of the correction selection image with respect to the background are calculated. Then, the code capacity determination unit 54 determines the data capacity of the background code and the data capacity of the foreground code by using the ratio of the first ratio value to the second ratio value (referred to as the third ratio) as the foreground ratio. . That is, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the set target data capacity, and the background code data capacity and the foreground code data capacity. The foreground code data capacity is calculated by multiplying the total by the third ratio, and the value obtained by subtracting the foreground code data capacity from the target data capacity is the background code data. Capacity.

  The picture compression unit 55 generates the background and foreground generated by the background / foreground generation unit 52 and appropriately converted by the resolution conversion unit 57 so that the code capacity determination unit 54 has the data capacity determined for each. Encode and compress.

  Next, the procedure of the multilayer image generation process performed by the image processing apparatus 50 according to the present embodiment will be described with reference to FIG. Here, it is assumed that the image is input by the scanner, the image quality of the image is specified via the operation input unit, and the resolution for converting at least one of the foreground and the background is specified. Steps S1 to S3 are the same as those in the first embodiment. In step S10, the image processing apparatus 50 converts the resolution of at least one of the foreground and the background into a resolution designated by the user. Then, the image processing device 50 generates a correction selection image for the target whose resolution is to be converted. Step S4 is the same as that in the first embodiment. In step S5, the image processing apparatus 50 counts the total number of foreground pixels (the number of pixels) in the correction selection image, calculates the ratio of the pixel to all the pixels of the correction selection image, and calculates the ratio as the background. A value obtained by multiplying the sum of the data capacity of the foreground code and the data capacity of the foreground code is determined as the data capacity of the foreground code. Then, the image processing apparatus 50 determines the value obtained by subtracting the data capacity of the foreground code from the sum of the data capacity of the background code and the data capacity of the foreground code as the data capacity of the background code. Steps S6 to S7 are the same as those in the first embodiment.

  According to the above configuration, the code amount is allocated to the foreground and the background so that the image quality in the multilayer image is improved while improving the compression rate by reducing the resolution of the foreground and the background. Can do.

[Third embodiment]
Next, an image processing apparatus, an image forming apparatus, an image processing method, and a program according to a third embodiment will be described. In addition, about the part which is common in the above-mentioned 1st Embodiment or 2nd Embodiment, it demonstrates using the same code | symbol or abbreviate | omits description.

  In the present embodiment, the foreground code data capacity and the background code data capacity are determined according to the document type designated by the user via the operation input unit. FIG. 10 is a diagram illustrating a functional configuration of the image processing apparatus 50 according to the present embodiment. As shown in the figure, the image processing apparatus 50 includes an image input receiving unit, a design / character separation unit 51, a background / foreground generation unit 52, a compression unit 53, a code capacity determination unit 54, and a design compression. In addition to the section 55 and the multi-layer structuring section 56, a document type correspondence table 58 is provided. The document type correspondence table 58 is stored in, for example, an auxiliary storage unit. In this embodiment, the ratio of the data capacity of the background code and the data capacity of the foreground code is set in advance with respect to the document type, and this correspondence relationship is stored in the document type correspondence table 58. FIG. 11 is a diagram illustrating a data configuration of the document type correspondence table 58. As shown in the drawing, in the document type correspondence table 58, the total ratio of the data capacity of the background code and the data capacity of the foreground code set in advance for each document type is “1”. Each ratio is stored in

  The code capacity determination unit 54 refers to the document type correspondence table 58 and uses the ratio of the data capacity of the background code and the data capacity of the foreground code corresponding to the document type specified by the user via the operation input unit. The data capacity of the background code and the data capacity of the foreground code are determined. Specifically, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the target data capacity, and the data capacity of the background code and the foreground code data. Calculate the total capacity, and multiply the total by the ratio of the foreground code data capacity corresponding to the document type to calculate the foreground code data capacity and target the foreground code data capacity to the target The data capacity of the code subtracted from the data capacity is set as the data capacity of the background code. For example, in the example of FIG. 11, when the document type is “character”, the code capacity determination unit 54 subtracts the data capacity of the mask code and the data capacity necessary for description in a predetermined format from the target data capacity. , Calculate the sum of the data capacity of the background code and the data capacity of the foreground code, and multiply the total by “0.2” to calculate the data capacity of the foreground code. The data capacity of the code obtained by subtracting the data capacity from the target data capacity is set as the data capacity of the background code.

  Next, the procedure of the multilayer image generation process performed by the image processing apparatus 50 according to the present embodiment will be described with reference to FIG. Steps S1 to S4 are the same as those in the first embodiment. In step S5, the image processing apparatus 50 refers to the document type correspondence table 58, and compares the data capacity of the background code and the data capacity of the foreground code corresponding to the document type designated by the user via the operation input unit. Are used to determine the data capacity of the background code and the data capacity of the foreground code. Steps S6 to S7 are the same as those in the first embodiment.

  According to the configuration described above, according to the type of document desired by the user, it is possible to assign code amounts to the foreground and the background so that the image quality in the multilayer image becomes better.

[Modification]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined. Further, various modifications as exemplified below are possible.

  In each of the embodiments described above, various programs executed by the image processing apparatus 50 may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. . The various programs are recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, and a DVD (Digital Versatile Disk) in a file in an installable or executable format. The computer program product may be provided.

  In each of the above-described embodiments, the image processing apparatus 50 further includes an image output unit such as a printer engine such as a plotter or a facsimile apparatus that forms and outputs an image on a recording medium such as paper using the generated multilayer image. You may prepare.

  In each embodiment described above, JPEG2000 is used as the encoding method. In this method, since the code data capacity can be controlled, the picture compressing unit 55 is configured so that the foreground code data capacity and the background code data capacity determined by the code capacity determining unit 54 are the foreground and The background encoding could be performed once. However, the present invention is not limited to this, and JPEG may be used as the encoding method. In this case, the picture compression unit 55 performs the foreground and background encoding a plurality of times so that the foreground code data capacity and the background code data capacity determined by the code capacity determination unit 54 are obtained. However, even if this method is used, a multilayer image with better image quality can be generated by assigning code amounts to the foreground and the background as described in the above embodiments.

  In each of the above-described embodiments, the target data capacity is set according to the image quality specified by the user. However, the present invention is not limited to this, and the user data may be specified by the user. Regardless, it may be set in advance.

  Note that, depending on the capacity of the input image, there is a case where the target data capacity set by the code capacity determining unit 54 may not be reached. Therefore, the pattern compressing unit 55 is less than the data capacity of the foreground code determined by the code capacity determining unit 54 and The foreground and the background may be encoded so as to be less than the data capacity of the background code.

  Further, in each of the above-described embodiments, the value obtained by subtracting the data capacity necessary for the description of the predetermined format and the data capacity of the mask code from the target data capacity set by the code capacity determination unit 54 is used as the background code. The total of the data capacity and the data capacity of the foreground code is not limited to this, but depending on the format, the value obtained by subtracting the data capacity of the mask code from the target data capacity may be the data capacity of the background code and the foreground. The total data capacity of the codes may be set.

  In each of the above-described embodiments, the code capacity determination unit 54 determines the data capacity of the background code and the data capacity of the foreground code using the selected image. The compression rate at the time and the compression rate at the time of encoding the foreground may be determined. In this case, the pattern compression unit 55 may encode the foreground and the background so that the foreground compression rate and the background compression rate determined by the code capacity determination unit 54 are obtained.

  In the first embodiment described above, the code capacity determination unit 54 multiplies the ratio of the pixels represented by the selected image to be classified as pixels representing non-characters with respect to all the pixels of the selected image. Thus, the data capacity of the background code may be calculated and used to determine the data capacity of the foreground code.

  In the first embodiment described above, when generating the foreground, the image processing apparatus 50 may unify the pixel values of pixels other than the pixels classified as characters among the pixels included in the foreground. . In the foreground, the pixel classified as a character in the selected image has a pixel value as information representing the color of the character, but the pixel classified as a non-character in the selected image generates a multilayer image. Since these are pixels that are not used for superimposing, the pixel value may be basically any value. However, since multi-layer image generation uses local correlation of the image, for example, random values are set as pixel values of pixels other than those classified as characters among pixels included in the foreground. In the latter case, the compression efficiency when the foreground is encoded is higher in the latter case when the pixel values representing colors such as white and black are unified.

  For example, it is assumed that the background / foreground generation unit 52 generates a foreground by replacing pixel values of pixels included in the foreground other than pixels classified as characters or lines with pixel values representing white. If the foreground has the same resolution as the input image, it will have the same number of pixels as the input image, but the number of pixels that actually have a color other than white is the number of pixels classified as characters or lines. The foreground capacity is considered to be smaller than the input image capacity. Therefore, since it is not necessary to assign a data capacity to the code for the foreground that has less influence on the overall image quality, in this case, the code capacity determination unit 54 determines the data capacity of the foreground code versus the background code. The data capacity of the foreground code and the background code is determined by using the ratio as the ratio of the number of pixels classified as characters or lines to the total number of pixels. For example, when the ratio of the pixel represented by the selected image to the pixel representing the character or line in the selected image is 1/5, “the number of pixels classified as the character or line: all Since the number of pixels = 1: 5, the foreground code data capacity and the background code data capacity are determined as “foreground code data volume: background code data volume = 1: 5”.

  According to the configuration as described above, it is possible to allocate a code amount to each of the foreground and the background so as to improve the image quality in the multilayer image while improving the foreground compression efficiency.

  Further, in the first embodiment described above, when generating the background, the image processing apparatus 50 removes the pixels represented by the selected image that are classified as the foreground from the input image, You may make it fill up with a pixel. FIG. 12 is a diagram for explaining background hole filling. Specifically, the image processing device 50 replaces the value of the pixel classified as the foreground (pixel value) with a value that is the same as or close to the value of a pixel that is a pixel near the pixel and classified as the background. To generate a background. As a result, the background compression efficiency can be increased. When background filling is performed, the code capacity determination unit 54 sets the ratio of the data capacity of the foreground code to the data capacity of the background code to the number of pixels classified as characters or lines to the number of pixels classified as non-characters. As the ratio, the data capacity of the foreground code and the data capacity of the background code are determined. For example, when the ratio of the pixels represented by the selected image to the pixels representing the character or line occupies 1/5 of all the pixels in the selected image, “the number of pixels classified as the character or line: non Since the number of pixels classified into characters = 1: 4, the foreground code data volume and the background code data volume are determined as “foreground code data volume: background code data volume = 1: 4”. To do.

  According to the configuration as described above, it is possible to assign a code amount to each of the foreground and the background so that the image quality in the multilayer image becomes better while enhancing the compression efficiency of the background.

  In the above-described third embodiment, the document type is specified by the user. However, the present invention is not limited to this, and the image processing apparatus 50 extracts features of the input image and uses the features to copy the document. By determining the type, the data capacity of the foreground code and the data capacity of the background code may be determined according to the document type.

  In the third embodiment described above, the foreground and background resolutions may be converted. In this case, the image processing apparatus 50 further includes a resolution conversion unit 57 as in the second embodiment. As described in the second embodiment, for example, when the foreground resolution is halved, the code capacity determination unit 54 determines the data capacity of the foreground code corresponding to the document type and the background. In the ratio of the data capacity of the code, the value of the ratio of the data capacity of the foreground code multiplied by “½ × 1/2” is used as the value of the ratio of the data capacity of the foreground code. Using the ratio value of the capacity, the ratio of the data capacity of the foreground code is calculated again, and the data capacity of the foreground code and the background code is determined using the ratio. Similarly, when converting the background resolution, the code capacity determination unit 54 again calculates the ratio of the data capacity of the background code corresponding to the document type, and the data capacity of the foreground code and the background code. To decide. When converting both the foreground and background resolutions, the code capacity determination unit 54 recalculates the foreground code data capacity ratio and the background code data capacity ratio corresponding to the document type, respectively. And the data capacity of the background code are determined.

DESCRIPTION OF SYMBOLS 50 Image processing apparatus 51 Picture / character separation part 52 Background / foreground generation part 53 Compression part 54 Code capacity determination part 55 Picture compression part 56 Multi-layer structuring part 57 Resolution conversion part 58 Original type correspondence table

JP 2008-236169A Japanese Patent No. 4064279

Claims (15)

Image input accepting means for accepting image input;
Based on the characteristics of the image, a first image representing a character or a line or a second pixel representing a character or a line other than the second pixel representing a character or a line. First generation means for generating a second image including one image and the second pixel;
A first encoding means for encoding the selected image and generating a code of the selected image;
A second encoding means for encoding the first image and the second image, respectively, and generating a code for the first image and a code for the second image;
An image processing apparatus comprising: a second generation unit configured to generate image data according to a predetermined format using the code of the first image, the code of the second image, and the code of the selected image.
A decision means for deciding at least one of a code data volume of the first image and a code data volume of the second image so that a data volume of the image data is equal to or less than a predetermined data volume;
The second encoding means respectively outputs the first image and the second image so as to have the data capacity determined for at least one of the code of the first image and the code of the second image. An image processing apparatus that performs encoding to generate a code for the first image and a code for the second image. The determining means includes
Calculating means for calculating the sum of the data capacity of the code of the first image and the data capacity of the code of the second image so that the data capacity of the image data is equal to or less than a predetermined data capacity;
Code capacity determining means for determining at least one of the code data capacity of the first image and the code data capacity of the second image with respect to the total using the selected image. The image processing apparatus according to claim 1. The code capacity determination unit is configured to determine whether the first image is included in the first image according to a ratio of pixels represented by the selected image to be classified as the first pixel among the pixels included in the selected image. The image processing apparatus according to claim 2, wherein the data capacity of the code is determined. Conversion means for converting the resolution of the first image;
A first corrected selection image that represents, for each pixel, whether the pixel is classified as the first pixel or the second pixel in correspondence with the pixel of the first image whose resolution is converted using the selection image. And a correction generation means for generating
The code capacity determination unit converts the resolution using a ratio of pixels represented by the first correction selection image to be classified as the first pixel among pixels of the first correction selection image. 4. The image processing apparatus according to claim 2, wherein a data capacity of a code of the first image is determined. The converting means further converts the resolution of the second image;
The correction generation unit uses the selected image to determine whether the pixel is classified as the first pixel or the second pixel in correspondence with the pixel of the first image whose resolution is converted. Further generating a second corrected selected image representing,
The code capacity determination means includes a ratio of pixels represented by the first correction selection image to be classified as the first pixel among pixels of the first correction selection image, and the second correction selection image. The data capacity and resolution of the code of the first image whose resolution has been converted using the ratio of pixels represented by the second correction selection image to be classified as the second pixel among the pixels of The image processing apparatus according to claim 4, wherein a data capacity of a code of the second image obtained by converting is determined. The first generation means is a pixel value that represents a pixel value that is the value of a pixel indicated by the selected image to be classified as the second pixel among the pixels of the first image. The image processing apparatus according to claim 2, wherein the first image replaced with is generated. The code capacity determination unit uses a ratio between a first pixel number that is the number of the first pixels among pixels of the selected image and a second pixel number that is the number of all pixels of the selected image. Then, the ratio of the number of first pixels is assigned as the ratio of the data capacity of the code of the first image, the ratio of the number of second pixels is assigned as the ratio of the data capacity of the code of the second image, and each ratio is used. The image processing apparatus according to claim 6, wherein a data capacity of the code of the first image and a data capacity of the code of the second image are determined with respect to the sum. The first generation means has a pixel value that is a value of a pixel represented by the selected image to be classified as the first pixel among pixels of the second image, which is the same as or approximate to a neighboring pixel. Generating the second image replaced with the value to be
The code capacity determination means determines the data capacity of the code of the first image according to a ratio of pixels represented by the selected image to be classified as the first pixel among pixels of the selected image. Determining a data capacity of a code of the second image according to a ratio of pixels represented by the selected image to be classified as the second pixel among pixels of the selected image. The image processing apparatus according to claim 2. The determining means is configured so that the data capacity of the image data is equal to or less than a predetermined data capacity, and the data capacity of the code of the first image and the data capacity of the code of the second image have a predetermined ratio. 2. The image processing apparatus according to claim 1, wherein a data capacity of the code of the first image and a data capacity of the code of the second image are determined. The determining means determines the data capacity of the code of the first image and the data capacity of the code of the second image according to the document type of the image so that the data capacity of the image data is equal to or less than a predetermined data capacity. The image processing apparatus according to claim 1, wherein at least one of the two is determined. Image input accepting means for accepting image input;
Based on the characteristics of the image, a first image representing a character or a line or a second pixel representing a character or a line other than the second pixel representing a character or a line. First generation means for generating a second image including one image and the second pixel;
A first encoding means for encoding the selected image and generating a code of the selected image;
A second encoding means for encoding the first image and the second image, respectively, and generating a code for the first image and a code for the second image;
An image processing apparatus comprising: a second generation unit configured to generate image data according to a predetermined format using the code of the first image, the code of the second image, and the code of the selected image.
A determining unit that determines at least one of the compression rate of the first image and the compression rate of the second image so that the data volume of the image data is equal to or less than a predetermined data volume;
The second encoding means encodes the first image and the second image so as to achieve the compression rate determined for at least one of the first image and the second image, respectively, An image processing apparatus for generating a code for a first image and a code for a second image, respectively. An image processing apparatus according to any one of claims 1 to 11,
An image forming apparatus comprising: an image forming unit that forms an image on a recording medium using the image data. An image processing method executed by an image processing apparatus including an image input receiving unit, a first generation unit, a first encoding unit, a second encoding unit, a second generation unit, and a determination unit. ,
The image input receiving means receives an image input; and an image input receiving step;
A selection image that represents, for each pixel, whether the first generation unit is classified as a first pixel representing a character or a line, or a second pixel representing other than a character and a line, based on the characteristics of the image; A first generation step of generating a first image including the first pixel and a second image including the second pixel;
A first encoding step in which the first encoding means encodes the selected image to generate a code of the selected image;
A second encoding step in which the second encoding means encodes the first image and the second image, respectively, and generates a code of the first image and a code of the second image;
A second generation step in which the second generation means generates image data according to a predetermined format using the code of the first image, the code of the second image, and the code of the selected image;
A determining step in which the determining means determines at least one of the code data capacity of the first image and the code data capacity of the second image so that the data capacity of the image data is equal to or less than a predetermined data capacity. Including
In the second encoding step, the first image and the second image are respectively set to have the data capacity determined for at least one of the code of the first image and the code of the second image. An image processing method, wherein encoding is performed to generate a code for the first image and a code for the second image. An image processing method executed by an image processing apparatus including an image input receiving unit, a first generation unit, a first encoding unit, a second encoding unit, a second generation unit, and a determination unit. ,
The image input receiving means receives an image input; and an image input receiving step;
A selection image that represents, for each pixel, whether the first generation unit is classified as a first pixel representing a character or a line, or a second pixel representing other than a character and a line, based on the characteristics of the image; A first generation step of generating a first image including the first pixel and a second image including the second pixel;
A first encoding step in which the first encoding means encodes the selected image to generate a code of the selected image;
A second encoding step in which the second encoding means encodes the first image and the second image, respectively, and generates a code of the first image and a code of the second image;
A second generation step in which the second generation means generates image data according to a predetermined format using the code of the first image, the code of the second image, and the code of the selected image;
And a determining step of determining at least one of the compression ratio of the first image and the compression ratio of the second image so that the data capacity of the image data is equal to or less than a predetermined data capacity. ,
In the second encoding step, the first image and the second image are respectively encoded so as to have the compression ratio determined for at least one of the first image and the second image. An image processing method comprising generating a code for a first image and a code for a second image, respectively.   A program for causing a computer to execute the method according to claim 13 or 14.

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