JP2012191556A - Image forming device, image forming method, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce memory capacity required when simultaneously reading the front and rear sides of a document in copying.SOLUTION: A scanner image processing unit 203 executes image processing on each block (image data having a fixed size) obtained by alternately reading the front and rear sides for each block from a memory 704. Data of the last several lines in the previous block is left on the memory 704 without discarding it, and it is transferred to the scanner image processing unit 203 in processing the next block.

Description

  The present invention relates to an image forming apparatus, an image forming method, a program, and a recording medium with a reduced memory capacity.

  When scanning both sides of a document in a scanning operation of a copier, etc., the method of reading the front side, turning it over, and then reading the back side makes the structure of the device complex and requires time for the turnover and increases the throughput. Go down. Therefore, there is a technique for reducing the size and increasing the speed by providing two systems of image sensors and reading both the front and back surfaces with a single document passing. In order to reduce the memory capacity when reading both sides at the same time, there is also a technique of transferring one side of the double-sided image read from the scanner to the image processing block and compressing and saving the one side (see Patent Document 1).

  However, since the method for reading both sides at the same time is based on the premise that it is installed in a high-function, high-performance copier, it is necessary to temporarily store at least one side of the image in a memory or hard disk. There was a problem that the cost required for primary storage increased.

The present invention has been made in view of the above-described problems.
An object of the present invention is to provide an image forming apparatus, an image forming method, a program, and a recording medium that reduce the memory capacity required for simultaneously reading the front and back sides of a document during copying.

  The present invention includes means for simultaneously reading the front and back sides of a document, storage means for storing the read image data for each image data (hereinafter referred to as a block) of a predetermined size, and a block for storing the front block and the back block. The front surface block and the back surface block that have been read are alternately read out, and image processing means for executing predetermined processing on each block, and when the image processing means processes the first block, The last predetermined size of image data of one block (hereinafter referred to as boundary data) is held in the storage means, and before the image processing means executes the processing of the second block, the boundary data is read from the storage means. The most important feature is that a reading control means is provided.

  According to the present invention, since image processing is alternately performed on the front surface and the back surface for each fixed-size image data, double-sided image processing can be realized by one image processing unit. In addition, when processing using multiple lines of image data, such as filter processing, scaling processing, halftone processing (error diffusion processing), etc., only the minimum image data necessary for boundary processing is retained. Therefore, it is not necessary to hold an image on the entire surface, and the memory capacity can be reduced.

1 shows a configuration of an entire image forming apparatus of the present invention. Indicates a scanner unit. The configuration inside the controller board is shown. The structure of error diffusion processing is shown. 1 illustrates a configuration of a scanner image input unit, a scanner image processing unit, and a printer image processing unit of the present invention. The structure of the error diffusion process part of this invention is shown. The processing flowchart of this invention is shown. 6 shows a timing chart of a reduction process of an input image storage memory.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the overall configuration of the image forming apparatus of the present invention. The image forming apparatus includes a scanner unit 102, a controller board 103, a plotter unit 104, and an operation unit 105, and is connected to a host 101 such as a PC.

  The scanner unit 102 reads a document, converts it into an electrical signal, and transmits it to the controller board 103. Here, an example in which an automatic document feeder (ADF) is provided and a function of automatically reading a plurality of documents is provided. In this case, either a CCD system or a CIS (contact image sensor) system can be used.

  The plotter unit 104 is a unit that prints an image read by the scanner 102 or image data input from the host 101 or the like into CMYK (+ α) data, and prints it on paper. Here, either the inkjet method or the electrophotographic method is used. It is possible.

  The operation unit 105 executes jobs such as copying, scanning, and FAX transmission, displays an image read by the scanner, and also uses it for various settings and error display.

  The controller board 103 is a unit that performs control such as copy processing and print processing. In the copy processing, the RGB multi-valued image input from the scanner unit 102 is converted into a format printable by the plotter unit 104. At that time, additional functions such as changing the page order, accumulating images, and editing the images are executed.

  FIG. 2 shows a scanner unit (for example, the scanner unit described in JP-A-2006-13822 is used here). The originals set on the document feeder 10 are fed one by one through the transport path 12 to the transport path 13 to the discharge tray 14 and the images on both sides are simultaneously read by the CIS 15 and the CCD image sensor 23. In this embodiment, the front side of the document is read by the CCD 23 and the back side is read by the CIS 15. However, the CCD 23 or both sides of the CIS 15 may be used.

  Both-side image signals are transmitted to the processing device 24 (within the controller board in FIG. 1), and image processing corresponding to each processing such as copying / scanning / FAX is performed. In FIG. 2, 11 is a document tray, 20 is a scanner device, 21 is a platen glass, and 22 is an illumination lamp.

  FIG. 3A shows the internal configuration of the controller board. A scanner engine control unit 201 performs sensor monitoring, motor control, image sensor control, and the like of the paper feeding device. The scanner image input unit 202 takes in RGB multi-value data input from the scanner unit 102. When it is received as analog data, it is converted to digital, and variation correction between elements and correction for differences in physical positions of elements are performed.

  The scanner image processing unit 203 performs processing for canceling the scanner characteristics and converts the data into standard RGB multi-value (e.g., 8-bit) data. The printer image processing unit 205 converts the print language (PDL) into standard RGB multi-value (e.g., 8-bit) data. The printer image processing unit 206 converts the standard RGB multi-value data into a data format (CMYK 2-bit data or the like) that can be output from the printer.

  The printer image output unit 208 is means for transmitting image data to the plotter unit 104 in the order and timing according to the specifications of the plotter unit 104. The printer engine control unit 207 performs monitoring of the sensor of the plotter unit 104, control of the motor, and the like.

  The host I / F 204 receives print job data from the PC 101 or the like and stores the print job data in the memory. The CPU 210 manages the job and controls the operation of all the components. Accepts the request and displays to notify the user of the status of the device.

  FIG. 3B shows the configuration of the scanner image input unit. The shading correction unit 301 corrects variation in characteristics for each light receiving element. Processing is realized by holding a correction coefficient for each of the light receiving elements and multiplying the input data of each pixel by the correction coefficient. Since the inter-line gap adjustment unit 302 has a different physical position of the light receiving element for each color, the timing for inputting data differs for each color even for the same pixel. The timing shift is corrected so that the data of the same pixel can be referred to at the same timing in the subsequent image processing. This is realized by temporarily buffering the image data and delaying it.

  FIG. 3C shows the configuration of the scanner image processing unit. In general, the scanner γ unit 401 corrects the distortion of the light receiving element because the output value does not have a linear characteristic with respect to the amount of light. With reference to the table, the output value for each input value is uniquely determined.

  The digital filter 402 corrects blurring of the image due to the characteristics of the light receiving element. Also, change the image characteristics according to user settings, such as sharpening in character mode. Refer to surrounding pixels (5x5 pixels, 7x7 pixels, etc.) and apply corrections that emphasize the amount of change, emphasize edges, and conversely make corrections that moderate the amount of change. Or blur the edges.

  The background removal unit 403 removes the background to make it easier to visually recognize when a document having a color is read even if it is a portion having no characters or pictures, such as newspaper. The main / sub scaling unit 404 changes the image at a magnification specified by the user and switches the resolution. There are simple enlargement in which the same pixels are simply repeated, simple reduction in which pixels are thinned out at a fixed rate, and scaling that allows an image to be drawn smoothly while referring to surrounding pixels.

FIG. 3D shows the configuration of the printer image processing unit 2. The color conversion unit 501 converts an RGB multivalued image into a CMYK multivalued image. There are the following conversion means.
-After calculating | requiring simply by subtraction (C = 255-R, ...), K is produced | generated.
Calculation by weighting RGB data (C = R × weighting coefficient + G × weighting coefficient + B × weighting coefficient + constant,...)
Reference a three-dimensional table (C = table [R] [G] [B]).

  The printer γ unit 502 corrects the distortion because the density output from the plotter 104 does not have linear characteristics with respect to the input data. With reference to the table, the output value for each input value is uniquely determined.

  The halftone processing unit 503 converts the CMYK multi-value data into small values (binary, quaternary, etc.) that can be output from the plotter 104. Dither processing and error diffusion processing are performed to reduce the value so that the gradation of the original data is not lost.

  FIG. 4 shows a configuration of error diffusion processing which is a kind of halftone processing. An error generated in surrounding pixels is added to input data by an adder 601, and a quantization process is performed by a quantization unit 602. The quantization unit 602 has a threshold value equal to the number of output gradations minus 1, and determines output data by comparing the threshold value with the added data.

  The inverse quantization unit 603 performs conversion for returning the quantized data again to the state before quantization (10 bits). The value before quantization and the value after inverse quantization are detected as an error 604 generated in the dot, and this error is diffused to surrounding pixels that have not yet been processed. When the stored error information is distributed and diffused to a plurality of surrounding pixels, a weighting unit 605 is required to weight each pixel. The generated error is stored in the line buffer 606 for diffusion to peripheral pixels.

  Here, in order to diffuse the error to the pixels of the next line, it is necessary to provide a line buffer for one line. As the number of input / output bits of the buffer increases, the capacity of the line buffer increases accordingly. As described above, when the error diffusion processing is executed, it is necessary to hold the error generated in the previous line in order to propagate to the next line.

  FIG. 5A shows the configuration of the scanner image input unit of the present invention. In the present invention, the two scanner input images on the front and back sides are temporarily stored in the memory. 5A includes two systems (front and back) of shading correction units 701 and 702 that perform shading correction, store the data after shading correction in the memory 704, and perform subsequent processing on one system of image processing unit. Processing is performed by the (scanner image processing unit, printer image processing unit 2).

The following two points can be cited as reasons for providing two types of shading correction (front surface and back surface). That is,
(1) In this embodiment, since the data format before shading correction is 10 bits and after shading correction is 8 bits, the memory capacity and memory bandwidth can be reduced after shading correction.
(2) The shading correction requires a correction coefficient for each pixel, and in order to perform processing with one system, a large amount of correction parameters are switched each time switching is performed, resulting in an increase in CPU load and a decrease in processing speed. This is because it is expected.
However, the data stored in the memory may be before shading correction or after subsequent processing. Further, in this embodiment, the inter-line gap adjusting unit 302 is omitted as compared with the conventional configuration of FIG. 3B. This is because the memory controller 703 stores the data once in the memory. This is because the gap is adjusted by setting the data write start address to the memory 704 and the data read start address to different values.

  FIG. 5B shows the configuration of the scanner image processing unit of the present invention. Except for reading image data from the memory 704, the scanner image processing unit 203 is the same as that shown in FIG.

  The scanner image after shading correction stored in the memory 704 is read out from the memory 704 for each fixed-size image data (for example, 128 lines: block), and the scanner image processing unit 203 converts the front and back images. Processed alternately. The necessary memory capacity can be reduced by discarding images that are no longer needed after processing and overwriting with new input data. At this time, in order to process a process (digital filter process 402, sub-scan scaling 404, etc.) that requires input data for a plurality of lines to obtain an output for one dot, the last few lines of the previous block The remaining memory data is left in the memory 704 without being discarded, and by referring to it at the time of processing the block boundary, processing equivalent to the prior art can be realized and image quality is not deteriorated.

  FIG. 5C shows the configuration of the printer image processing unit 206. The configuration of the printer image processing unit 206 is the same as that of the conventional FIG. 3D, but when storing the image after halftone processing in the memory 704, the memory controller 703 controls the memory write start address. Then, the images are stored in the memory 704 so that the images of the front and back surfaces become a series of images.

  FIG. 6 shows the configuration of the error diffusion processing unit of the present invention. In the error diffusion process, as described above, a process of adding an error generated one line before to the current pixel is performed. In the present invention, since two systems of images on the front and back sides of the paper are processed alternately, the error line buffer must also support two systems. In this embodiment, two systems are provided as the line buffers 801 and 802, and the error data of one line before is stored for each system, so that the error can be propagated correctly. Reference numerals 803 and 804 denote selection units.

  FIG. 7 shows a processing flowchart of the present invention. The processing in FIG. 7 is executed by the CPU 210 in the controller board 103 in FIG. In the processing flowchart of FIG. 7, it is assumed that 128 lines of input data are processed as one block and the front surface and the back surface are processed alternately. Further, in order to process the digital filter and the sub-scanning scaling, it is necessary to process by overlapping seven lines at the block boundary.

  That is, when the data (128 lines) of the first block on the front side is transferred from the memory to the image processing unit (for example, the scanner image processing unit 203) and processed, the last seven lines of the first block on the front side are stored in the memory. Before storing the second block (128 lines) on the front surface, the last seven lines of the first block on the front surface are transferred to the image processing unit (scanner image processing unit 203), and the second block on the front surface is processed. When processing the image data of the block, image processing such as filtering is performed with reference to the last seven lines of the first block on the surface, which is the boundary between the first and second blocks.

  When the scanning operation starts, when the first block is a front block (Yes in step 901), the process waits until data for 128 lines on the front surface is accumulated in the memory 704 (front surface memory) (step 904). If input data for 128 lines can be accumulated, data processing for 128 lines is performed (step 905). For example, the scanner image processing unit 203 performs data processing on 128 lines of surface data from the memory 704 (surface memory). When processing of input data for 128 lines is completed, data other than the last 7 lines of the first block are no longer necessary, so the memory on the surface for 121 lines can be released and the data for the next block can be stored. (Step 906). Similarly, the first block on the back surface is processed (step 907).

  For the second and subsequent blocks (No in step 901), the data for the last seven lines of the previous block is read from the surface memory so that the data does not become discontinuous at the line boundary (step 902), and the previous block whose input has been completed The memory area on the surface for the last 7 lines is released (step 903). Thereafter, waiting for image data for 128 lines to be accumulated (step 904), the same processing as in the first block is performed. In the processing of the second block, processing is performed with reference to the data for the last seven lines of the previous block read in step 902 (steps 905 and 906). The back side is processed in the same manner (steps 907 to 912), and when the final block is completed, the process ends (step 913).

  When image processing parameters (filter type / color conversion table / halftone processing pattern, etc.) are different between the front and back surfaces, it is necessary to rewrite the parameters (for example, filter coefficients) at the stage of switching between the front and back surfaces. . Therefore, different parameters are set for the front and back surfaces, and the parameter switching is implemented by hardware so that the front and back parameters are automatically switched. Thereby, the time lag required for parameter setting at the time of switching can be kept small.

  FIG. 8 is a timing chart of processing for further reducing the memory for storing input images.

  In FIG. 2, it is assumed that the front surface reading sensor 23 and the rear surface reading sensor 15 are physically installed at positions shifted by 64 lines (or 64 + 128 × N (N is an integer)). Further, it is assumed that the image processing speed is twice the data input speed.

  In this case, since a delay of 64 lines occurs until a valid image is input, the processing for 128 lines on the front surface is completed, and at the same time, the back surface processing can be started. It is possible to operate with the memory of minutes (when not considering the redundant use data at the line boundary). Note that when the front and back sensors are at the same position, 256 lines of memory are required for the back surface. Therefore, the processing of FIG. Memory can be kept small. In this way, it is possible to reduce the memory for storing images during simultaneous reading on both sides.

  According to the present invention, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus is stored in the storage medium. It is also achieved by reading and executing the program code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment. As a storage medium for supplying the program code, for example, a hard disk, an optical disk, a magneto-optical disk, a nonvolatile memory card, a ROM, or the like can be used. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) operating on the computer based on an instruction of the program code. A case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included. Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. A case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing is included. Further, the program for realizing the functions and the like of the embodiments of the present invention may be provided from a server by communication via a network.

101 Host 102 Scanner Unit 103 Controller Board 104 Plotter Unit 105 Operation Unit 201 Scanner Engine Control Unit 202 Scanner Image Input Unit 203 Scanner Image Processing Unit 204 Host I / F
205, 206 Printer image processing unit 207 Printer engine control unit 208 Printer image output unit 209 Operation unit I / F
210 CPU

JP 2003-259052 A

Claims (8)

  Means for simultaneously reading the front surface and the back surface of the document; storage means for storing the read image data for each predetermined size of image data (hereinafter referred to as a block); And the block on the back side are alternately read out, and image processing means for executing predetermined processing on each block, and when the image processing means processes the first block, Control means for holding the last predetermined size image data (hereinafter referred to as boundary data) in the storage means, and reading the boundary data from the storage means before the image processing means executes the processing of the second block. An image forming apparatus comprising the image forming apparatus.   The image processing means includes a first image processing means for converting the read image data into standard RGB image data, and a second image processing means for converting the standard RGB image data into output data of the image forming means. The image forming apparatus according to claim 1, further comprising:   3. The image forming apparatus according to claim 2, wherein the second image processing means executes halftone processing by error diffusion processing and includes error memories for the front surface and the back surface.   The image forming apparatus according to claim 2, wherein the first and second image processing units switch predetermined parameters set for each of the front surface and the back surface according to the processing of each surface.   The image forming apparatus according to claim 1, wherein the reading unit includes a front surface sensor and a back surface sensor arranged at different positions.   A step of simultaneously reading the front surface and the back surface of the document; a storing step of storing the read image data for each image data (hereinafter referred to as a block) of a predetermined size; and the stored front surface Block and back block are alternately read out, and an image processing step for executing a predetermined process on each block, and when the image processing step processes the first block, A control step of holding image data of the last predetermined size (hereinafter referred to as boundary data) in the storage step, and reading out the boundary data from the storage step before the image processing step executes processing of the second block An image forming method comprising:   A program for causing a computer to realize the image forming method according to claim 6.   A computer-readable recording medium on which a program for causing a computer to realize the image forming method according to claim 6 is recorded.

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