JP2013121083A - Image processing method, image processing apparatus, image forming apparatus including the same, image processing program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow image processing while suppressing a reduction in processing speed even in the case of a large number of pixels in image data to be processed.SOLUTION: An image processing apparatus determines which of first magnification processing and second magnification processing is performed on the basis of the number of input pixels and the number of output pixels (S302, S307), performs the first magnification processing before performing predetermined image processing when determined to perform the first magnification processing (S303 to S306), and performs the second magnification processing after performing a predetermined image processing when determined to perform the second magnification processing (S305 to S306, S308, S309).

Description

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

  A technique for suppressing a decrease in image processing speed in a digital color copying machine or a multifunction machine is known. For example, Patent Document 1 describes an image data interpolation apparatus that selects and executes an interpolation process that can obtain an optimum interpolation result with respect to an interpolation magnification. Specifically, the image data interpolating device described in Patent Document 1 executes the interpolation process by the nearest neighbor method when the interpolation magnification is equal to or smaller than a predetermined value, and when the interpolation magnification is larger than the predetermined value, the hybrid bicubic method Is expanded to a predetermined integer multiple, and interpolation processing is executed for the remaining interpolation magnification by the nearest neighbor method.

  The nearest neighbor method has a feature that the edge of the image is retained, and thus jaggy is likely to occur when the image is enlarged, but has a feature that the amount of calculation processing is small. The hybrid bicube method can sharpen the entire image, but has a feature that the amount of calculation processing is large. However, in the case of enlarging to an integral multiple, the amount of calculation processing can be relatively reduced.

  Therefore, when the interpolation magnification is less than or equal to a predetermined value, the amount of calculation processing is reduced by executing the interpolation processing by the nearest neighbor method. In addition, since the interpolation magnification at the time of interpolation processing is small, it is possible to suppress degradation of image quality. When the interpolation magnification is larger than the predetermined value, it is enlarged to a predetermined integer multiple by the hybrid bicubic method, and the remaining interpolation magnification is executed by the nearest neighbor method to suppress image quality deterioration. An increase in the amount of calculation processing in the entire interpolation processing is suppressed.

JP 2000-32256 A (published January 28, 2000)

  However, in the above-described conventional technology, even if the above-described interpolation processing is performed on an image having a large number of pixels and a large file size, for example, more than 10 million pixels, the amount of calculation processing for image processing other than the above-described interpolation processing Therefore, an increase in the calculation processing amount of the entire image processing cannot be suppressed. On the other hand, when an interpolation method is selected so as not to increase the calculation processing amount and the interpolation processing is executed, there is a problem that the image quality is deteriorated, for example, the image is blurred or jaggy occurs due to the outline of characters.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to enable image processing that suppresses a decrease in processing speed even when the number of pixels of image data to be processed is large. An image processing method, an image processing apparatus, an image forming apparatus including the image processing apparatus, an image processing program, and a recording medium are provided.

  In order to solve the above-described problems, an image processing apparatus according to the present invention includes an image processing control unit that controls execution of image processing on image data, and a first image that reduces an image based on the number of input pixels and the number of output pixels. A scaling factor determining unit that determines which one of a scaling process or a second scaling process for enlarging an image is performed, and the image processing control unit performs the first scaling process by the scaling factor determining unit. If it is determined that the second scaling process is executed, the second scaling process is performed by the scaling factor determination unit after the first scaling process is performed, and then the second scaling process is performed. Before executing the scaling process, the predetermined image processing is executed.

  According to the above configuration, it is determined whether to execute the first scaling process or the second scaling process based on the number of input pixels and the number of output pixels, and it is determined to execute the first scaling process. In this case, after the first scaling process is executed, a predetermined image process is executed, and when it is determined that the second scaling process is executed, the predetermined scaling process is executed before the second scaling process is executed. Image processing is executed.

  For this reason, when the predetermined image processing is executed after the first scaling process, the image size is reduced by the first scaling process. Can be reduced.

  Further, when a predetermined image process is executed before the second scaling process is executed, the predetermined image process is executed before the image size is increased by the execution of the second scaling process. Therefore, an increase in the amount of calculation processing can be suppressed.

  Therefore, even when the number of pixels of the image data to be processed is large, it is possible to provide an image processing apparatus that can perform image processing while suppressing a decrease in processing speed.

  Note that the predetermined image processing preferably includes background removal processing, color correction processing, black generation / undercolor removal processing, and spatial filter processing.

  In the image processing apparatus according to the aspect of the invention, the scaling factor determination unit may set an interpolation method during the first scaling process or the second scaling process based on the calculated scaling ratio. Including setting means.

  According to the above configuration, it is possible to set an appropriate interpolation method according to the scaling factor, so that the image quality can be improved.

  In the image processing apparatus of the present invention, the image processing control means includes first scaling processing means for executing the first scaling processing, and second scaling processing means for executing the second scaling processing. The first scaling processing means sets an interpolation method at the time of the first scaling processing based on the scaling ratio, and the second scaling processing means is based on the scaling ratio, Sets the interpolation method during the second scaling process.

  According to the above configuration, since it is not necessary to provide the interpolation calculation setting unit, the configuration can be simplified.

  In order to solve the above problems, an image forming apparatus of the present invention includes the above-described image processing apparatus.

  According to said structure, even if it is a case where there are many pixels of the image data of a process target, the image processing method which can perform the image processing which suppressed the fall of the processing speed can be provided.

  In order to solve the above problems, an image processing method according to the present invention includes an image processing control step for controlling execution of image processing on image data, and a first image reduction method based on the number of input pixels and the number of output pixels. A scaling factor determining step for determining which of the scaling processing or the second scaling processing for enlarging the image is performed, wherein the image processing control step executes the first scaling processing by the scaling factor determining step. If it is determined that the second scaling process is performed after the first scaling process is performed, then it is determined that the second scaling process is performed in the scaling ratio determination step. Before executing the double processing, the predetermined image processing is executed.

  According to said structure, even if it is a case where there are many pixels of the image data of a process target, the image processing method which can perform the image processing which suppressed the fall of the processing speed can be provided.

  The image processing apparatus may be realized by a computer. In this case, an image processing program for causing the image processing apparatus to be realized by the computer by causing the computer to operate as the respective means, and recording the program. Such computer-readable recording media are also included in the scope of the present invention.

  The present invention has an effect that even when the number of pixels of image data to be processed is large, it is possible to perform image processing while suppressing a decrease in processing speed.

1 is a configuration diagram of a digital color image forming apparatus as one embodiment according to the present invention. FIG. FIG. 3 is a configuration diagram when operating as a scan to e-mail function in a digital color image forming apparatus. It is a block diagram which shows the structure of a variable magnification determination part. It is a flowchart which shows the flow of a part of image processing performed in an image processing apparatus. It is a flowchart which shows the flow of a variable magnification calculation process.

  Embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(Configuration of image forming apparatus)
FIG. 1 is a configuration diagram of a digital color image forming apparatus as an embodiment according to the present invention. FIG. 1 shows a data flow in a so-called copy mode in which a document is read by an image input device 2 such as a scanner to generate image data, and an image based on the image data is generated and output by an image output device 4. ing.

  The image input apparatus 2 reads an original and generates image data in an image transmission mode such as a copy mode, a facsimile transmission mode, or a scan to e-mail. Further, the image input device 2 has a scanner unit including a CCD (Charge Coupled Device), converts light reflected from the document into an electrical signal (analog image signal) that is color-separated into RGB, and this The electric signal is output to the image processing device 3. The image input apparatus 2 reads a document image in full color regardless of whether the mode designation is a full color mode or a black and white mode.

  The image processing device 3 performs image processing on the image data (input image data) sent from the image input device 2 in the copy mode, the facsimile transmission mode, and the image transmission mode. In the print mode, image processing is performed on image data transmitted from a terminal device (not shown). In the facsimile reception mode, image processing is performed on image data received from an external device (not shown). The image processing apparatus 3 transmits the image data subjected to the image processing to the image output apparatus 4 in the copy mode, the print mode, and the facsimile reception mode. In the facsimile transmission mode, the image data subjected to image processing is transmitted to the transmission / reception device 5. Note that the image processing apparatus 3 performs image processing by appropriately storing image data in the storage unit 9.

  The image output device 4 prints (forms) an image of the image data sent from the image processing device 3 on a recording medium (for example, paper). For example, the image output device 4 can be a color printer using an electrophotographic system or an inkjet system.

  The transmission / reception device 5 is constituted by a modem or a network card, for example. The transmission / reception device 5 exchanges data with other devices (for example, personal computers, server devices, display devices, other digital multifunction devices, facsimile devices, etc.) connected to the network via network cards, LAN cables, etc. Send and receive. When transmitting and receiving image data, the transmission / reception device 5 reads out the image data compressed in a predetermined format from the storage unit 9 when the transmission state is ensured by performing a transmission procedure with the other party, and the compression format Necessary processing such as change is performed, and the data is sequentially transmitted to the other party via the communication line.

  Further, when receiving the image data, the transmission / reception device 5 performs a communication procedure, receives the image data transmitted from the other party, and outputs it to the image processing device 3. The received image data is subjected to predetermined processing such as expansion processing, rotation processing, resolution conversion processing, output gradation correction, gradation reproduction processing, and the like by the image processing apparatus 3 and is output by the image output apparatus 4. Note that the received image data may be stored in a storage device (not shown), and the image processing device 3 may read it out as necessary to perform the predetermined processing.

  The control unit (image processing control means) 7 is a computer including a processor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), and comprehensively controls various hardware included in the digital color image forming apparatus 1. To do. The control unit 7 also has a function of controlling data transfer between each hardware provided in the digital color image forming apparatus 1. In FIG. 1, the control unit 7 is illustrated as an external configuration of the image processing apparatus 3, but may be provided as a configuration within the image processing apparatus 3 together with the storage unit 9.

(Configuration of image processing apparatus 3)
The image processing apparatus 3 includes an A / D (analog / digital) conversion unit 11, a shading correction unit 12, an input processing unit 13, an automatic document discrimination unit 14, a first scaling processing unit (first scaling processing means) 15, Background removal processing unit 16, color correction unit 17, black generation / undercolor removal unit 18, spatial filter unit 19, second scaling processing unit (second scaling processing means) 20, output tone correction unit 21, halftone A generation unit 22, a scaling factor determination unit (scaling factor determination unit) 23, and a region separation unit 24 are included.

  The A / D (analog / digital) converter 11 converts the color image signal (RGB analog signal) sent from the image input device 2 into digital image data (RGB digital signal).

  The shading correction unit 12 performs processing for removing various distortions generated in the illumination system, the imaging system, and the imaging system of the image input device 2 on the image data sent from the A / D conversion unit 11.

  The input processing unit 13 performs gradation conversion processing such as γ correction processing on each of the RGB image data sent from the shading correction unit 12, and outputs it to the automatic document determination unit 14 and the magnification determination unit 23. .

  The data subjected to the above processing in the input processing unit 13 is transferred to the storage unit 9 and managed as filing data. In this case, the image data is stored after being compressed into a JPEG code based on, for example, a JPEG compression algorithm. When a copy output operation or a print output operation is instructed, a JPEG code is extracted from the hard disk, transferred to a JPEG decompression unit (not shown), decoded, and converted into RGB data.

  On the other hand, in the case of an image transmission operation, a JPEG code is extracted from the hard disk, delivered to a JPEG decompression unit (not shown), decoded, converted to RGB data, converted to a PDF file, and a mail processing unit (not shown) The data is transmitted to the external connection device or communication line via the network or communication line. Note that the control unit 7 performs filing data management and data transfer operation control. Note that the image data after the processing in the automatic document discrimination section 14 may be filed.

  The automatic document determination unit 14 determines the document type such as whether the read document is a character document, a printed photo document, or a character printed photo document in which characters and a printed photo are mixed. Further, it is determined whether the read original is a color original or a monochrome original (ACS: Auto Color Selection) or a blank original (plain original).

  The scaling factor determination unit 23 performs processing in either the first scaling unit 15 or the second scaling unit 20 described later based on the scaling factor calculated based on the number of input pixels and the number of output pixels. And a determination signal indicating the determination result is generated. The determination signal includes a first determination signal and a second determination signal. The first determination signal indicates an instruction to execute the process, and the second determination signal indicates an instruction to pass through the process. The scaling factor determination unit 23 outputs the generated determination signal to the first scaling processing unit 15 and the second scaling processing unit 20. The scaling factor determination unit 23 sets an interpolation method for performing scaling processing based on the calculated scaling factor.

  The region separation unit 24 determines what kind of region each pixel of the input image data belongs to based on the RGB signal (RGB density signal) input from the automatic document determination unit 14. For example, it is determined whether the pixel belongs to any region such as a black character, a color character, or a halftone dot. The area separation process executed by the area separation unit 24 may be in a form in which an image area is determined in units of a plurality of pixels instead of a form in which an image area is determined for each pixel. The region separation unit 24 outputs a region separation signal as a determination result to the black generation / undercolor removal unit 18, the spatial filter unit 19, and the halftone generation unit 22.

  The first scaling processing unit 15 determines whether or not to execute the first scaling processing for reducing the image, based on the determination signal input from the scaling factor determination unit 23. The first scaling unit 15 determines to execute the first scaling process when the first determination signal is input from the scaling factor determination unit 23, and the second determination signal is input from the scaling factor determination unit 23. If so, it is determined not to execute the first scaling process.

  When the first scaling processing unit 15 determines to execute the first scaling processing, the first scaling processing unit 15 performs the first scaling processing for reducing the image with the scaling factor included in the determination signal input from the scaling factor determination unit 23. The process is executed on the image data input from the automatic document discrimination unit 14. Further, when the first scaling process is executed, the interpolation process is executed by the interpolation method set by the scaling ratio determining unit 23. The first scaling processing unit 15 outputs the processed image data to the background removal processing unit 16. If the first scaling process unit 15 determines not to execute the first scaling process, the first scaling process unit 15 passes the image data input from the automatic document discrimination unit 14 and outputs the image data to the background removal processing unit 16.

  The background removal processing unit 16 performs background removal processing based on the determination result determined by the automatic document determination unit 14 and the background removal removal level input from the operation panel (not shown) by the user.

  The color correction unit 17 performs processing for removing color turbidity based on the spectral characteristics of CMY (C: cyan, M: magenta, Y: yellow) color materials including unnecessary absorption components in order to realize faithful color reproduction. .

  The black generation / under color removal unit 18 generates black (K) signals from the CMY three-color signals after color correction by the color correction unit 17, and subtracts the K signals obtained by black generation from the original CMY signals. To generate a new CMY signal. As a result, the CMY three-color signal is converted into a CMYK four-color signal.

  The spatial filter unit 19 performs spatial filter processing (enhancement processing and / or smoothing processing) using a digital filter on the image data of the CMYK signal input from the black generation / undercolor removal unit 18 based on the region separation signal. And correct the spatial frequency characteristics. As a result, blurring of the output image and deterioration of graininess can be reduced.

  The second scaling processing unit 20 determines whether or not to execute the second scaling processing for enlarging the image, based on the determination signal input from the scaling factor determination unit 23. Specifically, when the determination signal input from the scaling factor determination unit 23 indicates execution of the second scaling processing, it is determined to execute the second scaling processing, and is input from the scaling factor determination unit 23. When the determination signal indicates execution of the first scaling process, it is determined not to execute the second scaling process.

  When the second scaling processing unit 20 determines to execute the second scaling processing, the second scaling processing unit 20 performs the second scaling processing for enlarging the image with the scaling factor included in the determination signal input from the scaling factor determination unit 23. This is performed on the image data input from the spatial filter unit 19. Further, during the second scaling process, the interpolation process is executed by the interpolation method set by the scaling factor determination unit 23. The second scaling processing unit 20 outputs the processed image data to the output tone correction unit 21. If the second scaling processing unit 20 determines not to execute the second scaling processing, the second scaling processing unit 20 passes through the image data input from the spatial filter unit 19 and outputs the image data to the output tone correction unit 21.

  The output tone correction unit 21 performs output γ correction processing for outputting image data to a recording medium such as paper.

  The halftone generation unit 22 performs tone reproduction processing for outputting an image using error diffusion processing and dither processing on the image data of the CMYK signal based on the region separation signal.

  For example, in the region separated into characters by the region separation unit 24, the high frequency enhancement amount is increased by the sharp enhancement processing in the spatial filter processing by the spatial filter unit 19 in order to improve the reproducibility of black characters or color characters in particular. The At the same time, the halftone generation unit 22 selects binarization or multi-value processing on a high-resolution screen suitable for high frequency reproduction. Further, with respect to the region separated into halftone dot regions by the region separation unit 24, the spatial filter unit 19 performs low-pass filter processing for removing the input halftone dot component.

  Then, the output tone correction unit 21 performs output tone correction processing for converting a signal such as a density signal into a halftone dot area ratio that is a characteristic value of the image output device 4. In particular, gradation reproduction processing (halftone generation) is performed in which an image is separated into pixels and processed so that each gradation can be reproduced. For the region separated into photographs by the region separation unit 24, binarization or multi-value processing is performed on the screen with an emphasis on gradation reproducibility.

  The CMYK signal output from the halftone generation unit 22 is output to the image output device 4, and a final output image is formed in the image output device 4.

(Another configuration of digital color image forming device)
FIG. 2 is a configuration diagram when the digital color image forming apparatus operates as a scan to e-mail function. When operating as a scan to e-mail function, the formatting processing unit 25 operates in the digital color image forming apparatus 1. Further, each of the black generation / undercolor removal unit 18 and the halftone generation unit 22 does not perform processing on input image data. Therefore, in the digital color image forming apparatus 1 when operating as a scan to e-mail function, the black generation / undercolor removal unit 18 converts the CMY three-color signal into the CMYK four-color signal as image data. However, the image data is output to each section subsequent to the black generation / undercolor removal section 18 without being executed.

  In addition, the color correction unit 17 converts the image data into R′G′B ′ image data (for example, sRGB data) suitable for display characteristics of a display device that is generally spread. Therefore, the image data output from the halftone generating unit 22 is R′G′B ′ image data.

  The formatting processing unit 25 changes the image data of R′G′B ′ output from the halftone generation unit 22 to the PDF format. The image data changed to the PDF format by the formatting processing unit 25 is attached to an e-mail by a mail processing unit (not shown), and the e-mail is transmitted to the other party via the network.

(Configuration of variable magnification determination unit)
FIG. 3 is a block diagram illustrating a configuration of the scaling factor determination unit. As shown in FIG. 3, the scaling factor determination unit 23 includes a scaling factor calculation unit 31, a scaling factor comparison unit 32, and an interpolation calculation setting unit (interpolation calculation setting means) 33.

  The scaling factor calculation unit 31 calculates the ratio of the number of input pixels with respect to the number of output pixels as a first scaling factor, and outputs the first scaling factor to the scaling factor comparison unit 32, as shown in the following equation (1). However, when the page aggregation function is set (when the page aggregation function is set, it is performed from the operation panel), after calculating the first scaling factor, the page aggregation scaling factor determined for the page aggregation function is calculated. Is multiplied by the first scaling factor to calculate the second scaling factor (see Equation 2 below), and the second scaling factor is output to the scaling factor comparison unit 32.

First variable magnification (%) = number of input pixels / number of output pixels × 100 (Expression 1)
Second scaling factor (%) = (number of input pixels / number of output pixels) × page aggregation scaling factor × 100
... (Formula 2)
The number of input pixels may be, for example, the number of pixels set for each paper size and reading resolution read by the image input apparatus 2 (for example, when reading at A4 size and 600 dpi, the vertical pixel is 7000 pixels and the horizontal is 5000 pixels). . The number of pixels when taken with a digital camera or the like (for example, in the case of a digital camera with a CCD of about 10 million pixels mounted is assumed to be 3500 pixels long and 3000 pixels wide).

  The paper size read by the image input device 2 can be set from the operation panel described above. Further, in the case of a multifunction peripheral that can set the reading resolution from the operation panel, the number of input pixels is set based on the reading resolution set by the user. In the case of image data captured by a digital camera, image data captured from a USB (Universal Serial Bus) terminal provided in the image forming apparatus or a CF (Compact Flash (registered trademark)) card connected to a card reader is temporarily stored. The number of vertical and horizontal pixels stored in the storage unit 9 and read out from the Exif (Exchangeable Image File Format) information of the image data stored in the storage unit 9 is set as the number of input pixels.

  The number of output pixels is calculated based on the output paper size and output resolution selected by the user. For example, in the case of outputting at A3 size and 600 dpi, it may be 10000 pixels vertically and 7000 pixels horizontally.

  For example, in the case of a page aggregation function of 2 in 1 (outputting two originals on one sheet), the second scaling factor is calculated as shown in Table 1 below.

  Note that the scaling factor is calculated in each of the vertical direction and the horizontal direction of the image data, and when each scaling factor is different, either one (for example, the smaller scaling factor) is selected as the first scaling factor. Good.

  The scaling factor comparison unit 32 compares the scaling factor input from the scaling factor calculation unit 31 with a predetermined value. Here, the predetermined value is 100%. The scaling factor comparison unit 32 determines to execute the first scaling process if the scaling factor input from the scaling factor calculation unit 31 is less than a predetermined value, but performs the second scaling process if it is greater than the predetermined value. Determine to execute.

  When it is determined that the first scaling process or the second scaling process is to be performed, the scaling factor comparison unit 32 outputs the determination result and the scaling factor input from the scaling factor calculation unit 31 to the interpolation calculation setting unit 33. . When the scaling factor input from the scaling factor calculation unit 31 is equal to the predetermined value, it is determined that the first scaling process and the second scaling process are not executed, and the determination result is output to the interpolation calculation setting unit 33.

  The interpolation calculation setting unit 33 sets an interpolation method associated with the scaling factor calculated by the scaling factor calculation unit 31. The interpolation method includes, for example, a bilinear method, a nearest neighbor method, and a bicubic method. Bilinear methods are associated with scaling factors below 50%, nearest neighbor methods are associated with scaling factors in the range of 50-99%, bilinear methods are associated with scaling factors in the range of 101-149%, The bicubic method is associated with a scaling factor of 150% or more.

  The bilinear method is a method in which an average of values weighted in a form proportional to the distance between four existing pixels surrounding a pixel to be interpolated is obtained, and that value is interpolated as the interpolated pixel. The nearest neighbor method is a method of performing an interpolation operation using a value of an existing pixel closest to the pixel to be interpolated or having a predetermined positional relationship with the pixel to be interpolated as the value of the interpolated pixel. The bicubic method is a method of performing interpolation calculation using the values of a total of 16 pixels including 12 points surrounding them in addition to 4 points surrounding pixels to be interpolated.

  In addition, when the determination result input from the scaling factor comparison unit 32 indicates that the first scaling process or the second scaling process is to be executed, the interpolation calculation setting unit 33 outputs a first determination signal indicating a process execution instruction. A second determination signal indicating an instruction to generate and pass through the process is generated. The first determination signal includes a scaling factor input from the scaling factor calculation unit 31 and an interpolation method associated with the scaling factor.

  When the determination result input from the scaling factor comparison unit 32 indicates that the first scaling process is to be performed, the interpolation calculation setting unit 33 outputs a first determination signal to the first scaling process unit 15 and the second scaling process is performed. The determination signal is output to the second scaling processing unit 20. When the determination result input from the scaling factor comparison unit 32 indicates that the second scaling process is to be performed, the first determination signal is output to the second scaling process unit 20, and the second determination signal is output to the first scaling factor. Output to the processing unit 15.

  When the determination result input from the scaling factor comparison unit 32 indicates that the first scaling process and the second scaling process are not performed, the interpolation calculation setting unit 33 generates a second determination signal and generates a second determination signal. Are output to the first scaling unit 15 and the second scaling unit 20, respectively.

  (Operations of the first scaling unit and the second scaling unit)

  Table 2 summarizes the operations of the first scaling unit 15 and the second scaling unit 20 for each scaling factor. When the scaling factor is 101% or more, the first scaling processing unit 15 shows an operation according to the second determination signal, and the second scaling processing unit 20 shows an operation according to the first determination signal. When the scaling factor is 99% or less, the first scaling processing unit 15 shows an operation according to the first determination signal, and the second scaling processing unit 20 shows an operation according to the second determination signal. When the zoom ratio is 100%, the first zoom processing unit 15 and the second zoom processing unit 20 indicate operations according to the second determination signal.

  When the scaling factor included in the determination signal is less than 50%, the interpolation method associated with the scaling factor included in the determination signal is a bilinear method.

  Therefore, the first scaling processing unit 15 performs an interpolation process based on the bilinear method during the scaling process, and the second scaling processing unit 20 passes through the image data input from the spatial filter unit 19. Therefore, in this case, since the bilinear method is used at the time of the first scaling process, it is possible to make it difficult to generate jaggy on the contour portion of the character edge even if the reduction ratio is large.

  When the scaling factor included in the determination signal is 50% or more and 99% or less, the interpolation method associated with the scaling factor included in the determination signal is the nearest neighbor method.

  Therefore, the first scaling processing unit 15 performs an interpolation process based on the nearest neighbor method during the scaling process, and the second scaling processing unit 20 passes through the image data input from the spatial filter unit 19. Therefore, in this case, since the nearest neighbor method having a small amount of calculation processing at the time of the first scaling process is used, the processing speed can be made relatively faster than using the bilinear method.

  When the scaling factor included in the determination signal is 101% or more and 149% or less, the interpolation method associated with the scaling factor included in the determination signal is a bilinear method.

  For this reason, the first scaling processing unit 15 passes through the image data input from the automatic document discrimination unit 14, and the second scaling processing unit 20 executes an interpolation process based on the bilinear method during the scaling process. Therefore, in this case, since the bilinear method is used at the time of the second scaling process, it is possible to make it difficult to generate jaggy in the contour portion of the character edge.

  When the scaling factor included in the determination signal is 150% or more, the interpolation method associated with the scaling factor included in the determination signal is the bicubic method.

  For this reason, the first scaling processing unit 15 passes through the image data input from the automatic document discrimination unit 14, and the second scaling processing unit 20 performs an interpolation process based on the bicubic method during the scaling process. Therefore, in this case, since the bicubic method is used at the time of the second scaling process, blurring at the time of enlargement can be suppressed as compared with the bilinear method.

  Here, based on the result of Table 2, each of the first scaling unit 16 to the second scaling unit 20 will be described. When the scaling ratio is 101% or more, the second scaling process is performed on the image data without performing the first scaling process, and the background removal processing unit 16 to the spatial filter unit 19 in the previous stage perform the processing. Run.

  For this reason, each of the background removal processing unit 16 to the spatial filter unit 19 can execute processing on the image data before the image size is increased by the processing of the second scaling processing unit 20. Thereby, the increase in the amount of arithmetic processing of each of the background removal processing unit 16 to the spatial filter unit 19 can be suppressed.

  On the other hand, when the scaling ratio is 99% or less, the first scaling process is performed on the image data without performing the second scaling process, and each of the subsequent background removal processing unit 16 to spatial filter unit 19 performs Execute the process.

  For this reason, each of the background removal processing unit 16 to the spatial filter unit 19 can execute processing on the image data after the image size is reduced by the processing of the first scaling processing unit 15. Thereby, it is possible to reduce the calculation processing amount of each of the background removal processing unit 16 to the spatial filter unit 19.

  The operations of the first scaling unit 15 and the second scaling unit 20 are not limited to Table 2. The range of the scaling factor may be further divided into the respective operations of the first scaling unit 15 and the second scaling unit 20, and the first scaling unit 15 and the second scaling unit 20 may be divided into two categories, ie, when reducing and when enlarging. The operations of the scaling processing unit 15 and the second scaling processing unit 20 may be determined.

  Further, although the variable magnification determination unit 23 includes the variable magnification calculation unit 31, the variable magnification comparison unit 32, and the interpolation calculation setting unit 33, the configuration is not limited thereto. The scaling factor determination unit 23 includes a scaling factor calculation unit 31 and a scaling factor comparison unit 32, and each of the first scaling processing unit 15 and the second scaling processing unit 20 further has a function of an interpolation calculation setting unit 33. It may be.

(Image processing flow)
FIG. 4 is a flowchart showing a part of image processing executed in the image processing apparatus. Here, a flow of processing executed in the scaling factor determination unit 23 and the first scaling processing unit 15 to the second scaling processing unit 20 will be described.

  As shown in FIG. 4, the scaling factor determination unit 23 executes scaling factor determination processing (S301). Here, the scaling factor determination process will be described.

  FIG. 5 is a flowchart showing the flow of the scaling factor determination process. As shown in FIG. 5, the scaling factor calculation unit 31 sets the number of input pixels and the number of output pixels (S401). Then, the first scaling factor is calculated according to the above equation 1 (S402).

  In the next step S403, the scaling factor calculation unit 31 determines whether or not the page aggregation function is set. If the page aggregation function is set, the process proceeds to step S404; otherwise, the process proceeds to step S405.

  In step S404, the scaling factor calculation unit 31 multiplies the page scaling factor determined for the set page aggregation function by the first scaling factor calculated in step S402, thereby obtaining the second scaling factor. Is calculated, and the process proceeds to step S405.

  In step S405, the interpolation calculation setting unit 33 sets an interpolation method associated with the calculated scaling factor, and advances the process to step S406.

  In step S406, if the calculated scaling factor is greater than a predetermined value, a first determination signal including the calculated scaling factor and the interpolation method set in step S405 is output to the first scaling processing unit 15. The second determination signal is output to the second scaling processing unit 20.

  If the calculated scaling factor is less than the predetermined value, a first determination signal including the calculated scaling factor and the interpolation method set in step S405 is output to the second scaling processing unit 20, and the second determination is performed. The signal is output to the first scaling processing unit 15.

  When the calculated scaling factor is equal to the predetermined value, the second determination signal is output to the first scaling unit 15 and the second scaling unit 20.

  Returning to FIG. 4, in step S <b> 302, the first scaling unit 15 determines whether or not there is an instruction to execute the first scaling process. Specifically, it is determined whether or not to execute the first scaling process based on the determination signal output in step S406. If the first determination signal is input, the process proceeds to step S303. If the second determination signal is input, the process proceeds to step S305.

  In step S303, the first scaling processing unit 15 executes a first scaling process for reducing an image with a scaling factor included in the input first determination signal. Then, interpolation processing is executed by the interpolation method included in the first determination signal (S304).

  In the next step S305, the color correction unit 17 executes color correction processing, the black generation / under color removal unit 18 executes black generation / under color removal processing, and the process proceeds to step S306.

  In step S306, the spatial filter unit 19 executes a spatial filter process. Then, the second magnification processing unit 20 determines whether or not there is an instruction to execute the second magnification processing (S307). Specifically, it is determined whether or not to execute the second scaling process based on the determination signal output in step S406. If the first determination signal is input, the process proceeds to step S308. If the second determination signal is input, the process ends.

  In step S308, the second scaling processing unit 20 executes a second scaling process for enlarging the image with a scaling factor included in the input first determination signal. Then, an interpolation process is executed by the interpolation method included in the first determination signal (S309).

(Summary)
As described above, when the scaling factor is less than 100%, the image is reduced based on the scaling factor before execution of image quality adjustment processing such as color correction processing and filter processing, and when the scaling factor is 101% or more, the image Execute the image quality adjustment process before zooming in. Thereby, it is possible to suppress a decrease in the speed of the image quality adjustment process.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  Finally, each block of the image processing apparatus 3 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the image processing apparatus 3 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program of the image processing apparatus 3 which is software that realizes the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the image processing apparatus 3 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The image processing apparatus 3 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

DESCRIPTION OF SYMBOLS 1,1A Digital color image forming apparatus 2 Image input apparatus 3 Image processing apparatus 4 Image output apparatus 5 Transmission / reception apparatus 7 Control part (image processing control means)
9 Storage unit 11 A / D conversion unit 12 Shading correction unit 13 Input processing unit 14 Automatic document discrimination unit 15 First scaling processing unit (first scaling processing means)
16 Background removal processing unit 17, 17A Color correction unit 18 Black generation / under color removal unit 19 Spatial filter unit 20 Second scaling processing unit (second scaling processing means)
21 output tone correction unit 22 halftone generation unit 23 variable magnification determination unit (variable magnification determination means)
24 region separation unit 25 formatting processing unit 31 scaling factor calculation unit 32 scaling factor comparison unit 33 interpolation calculation setting unit (interpolation calculation setting means)

Claims (8)

Image processing control means for controlling execution of image processing on the image data;
A scaling factor determination for determining whether to execute a first scaling process for reducing an image or a second scaling process for enlarging an image, based on a scaling factor calculated based on the number of input pixels and the number of output pixels Means, and
The image processing control means executes predetermined image processing after executing the first scaling process when the scaling ratio determination means determines that the first scaling process is to be executed, and the scaling ratio is determined. An image processing apparatus, wherein when the determination unit determines that the second scaling process is to be executed, the predetermined image processing is executed before the second scaling process is executed.   The image processing apparatus according to claim 1, wherein the predetermined image processing includes at least one of background removal processing, color correction processing, black generation / undercolor removal processing, and spatial filter processing. .   The scaling factor determination unit includes an interpolation calculation setting unit that sets an interpolation method at the time of the first scaling process or the second scaling process based on the calculated scaling factor. The image processing apparatus according to claim 1. The image processing control means includes
First scaling processing means for executing the first scaling processing;
Second scaling processing means for executing the second scaling processing;
The first scaling processing means sets an interpolation method during the first scaling processing based on the scaling ratio,
The image processing apparatus according to claim 1, wherein the second scaling processing unit sets an interpolation method during the second scaling processing based on the scaling ratio.   An image forming apparatus comprising the image processing apparatus according to claim 1. An image processing control step for controlling execution of image processing on the image data;
A scaling factor determining step for determining whether to execute a first scaling process for reducing an image or a second scaling process for enlarging an image based on the number of input pixels and the number of output pixels;
When the image processing control step determines that the first scaling process is to be executed by the scaling factor determination step, the image processing control step executes a predetermined image processing after executing the first scaling process, and the scaling factor An image processing method, wherein, when it is determined in the determination step that the second scaling process is to be executed, the predetermined image processing is executed before the second scaling process is executed.   An image processing program for operating the image processing apparatus according to any one of claims 1 to 4, wherein the image processing program causes a computer to function as each means described above.   A recording medium storing the image processing program according to claim 7 in a computer-readable manner.

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