JP2004104662A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device for suppressing erroneous determination of character photograph discrimination processing which is generated by the influence of being visible from the other side of an original. <P>SOLUTION: First, an image input device 1 reads an original image (S11). Processing for eliminating components of being visible from the other side is applied to digital original image data prepared by reading the original image (S12). The character photograph discrimination processing is applied to the digital original image data whose components of being visible from the other side has been eliminated by the processing for eliminating components of being visible from the other side (S13). Here, whether a character part or a photograph part is discriminated for each part of the digital original image data. Next, filtering processing is applied to the digital original image data discriminated by dividing character parts from photograph parts by the character photograph discrimination processing (S14). The filtered digital original image data are subjected to image printing processing (S15) to finish the processing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus capable of determining a character portion and a photographic image portion from a read image and performing a character / photo determination process of performing image processing corresponding to each portion based on the determination result.
[0002]
[Prior art]
In recent years, digital copiers and color digital copiers that create input information using a scanner device that reads original images such as pictures and characters and converts them into digital data, and forms output images based on the digital input information created Image forming apparatuses have become widespread. Further, with the spread of these image forming apparatuses, development of various functions mounted on the image forming apparatuses is also progressing.
For example, one of these functions is a character / photograph discrimination processing function of discriminating a character portion and a photograph (including a picture) portion from a read image and performing image processing corresponding to each portion based on the discrimination result. There is.
When this text-photo discrimination processing function is used, the edge determined to be text is sharpened sharply to sharpen it, and a smoothing filter is applied to one photo to prevent moiré. Is performed, and high-quality image data can be generated.
[0003]
2. Description of the Related Art Conventionally, various techniques for character / photograph discrimination processing have been disclosed, including the following patent documents.
[Patent Document 1]
JP-A-9-238253 [Patent Document 2]
Japanese Patent Application Laid-Open No. H11-136512 discloses a technique in which a histogram is created from input image data and the number of pixels is calculated from the created histogram to determine image attributes (text, photograph, background). It has been disclosed.
Japanese Patent Application Laid-Open No. H11-163873 discloses a technique of binarizing multi-valued image data input by using an error diffusion method and calculating a density error of the binarized image data, thereby obtaining an area where a pixel exists ( A technique for determining a binary image area or a halftone area) is disclosed.
[0004]
[Problems to be solved by the invention]
By the way, when reading a document on which double-sided printing is performed and inputting image data, “show-through” often occurs in which the image on the back side is transparently mixed with the image on the front side.
However, in the above-described conventional technology for character / photograph discrimination processing, no consideration has been given to a case where a misjudgment is caused by the influence of the “show-through”. In other words, the image data input for “show-through” is also subjected to the character / photograph discrimination processing in the same manner as the original image data. Therefore, the quality of the output image may be reduced.
Therefore, the present invention provides an image forming apparatus capable of improving the accuracy of the text / photo determination process by suppressing erroneous determination of the text / photo determination process caused by the influence of “show-through” of the document. Aim.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an image data creating means for reading an original image and creating image data, and detecting the intensity of an edge which is a boundary portion of an image from the image data created by the image data creating means. Means, determining means for determining a background color image of the document image based on the intensity of the edge detected by the detecting means, and back-processing from the image data based on the background color image determined by the determining means. A removing unit for removing a reflection component, a comparing unit for comparing the show-through component-removed image data from which the show-through component has been removed by the removing unit, and predetermined pattern data, and a comparison result obtained by the comparing unit. A character / photograph discriminating means for discriminating a character portion and a photograph portion of the show-through component-removed image data based on the A correcting unit that corrects data for each part of the image data from which the show-through component has been removed, based on the obtained determination result, and prints and outputs the corrected image data that has been subjected to the correcting process by the correcting unit; The above object is achieved by providing an image forming means for forming an image.
[0006]
According to a second aspect of the present invention, in the first aspect of the present invention, the object is achieved by including a removal processing accepting unit that accepts a selection as to whether or not there is a show-through component removal process by the removing unit.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the object is achieved by including a removal processing intensity receiving unit that receives a selection of a processing intensity of a show-through component by the removal unit. .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the image forming apparatus of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a block diagram illustrating a schematic configuration of the image forming apparatus according to the present embodiment.
As shown in FIG. 1, the image forming apparatus includes an image input device 1, a display device 2, a keyboard 3, an image printing device 4, a CPU (central processing unit) 5, a ROM (read only memory) 6, and a RAM. (Random access memory) 7, each of which is connected via a bus 8.
[0008]
Hereinafter, each of the above blocks will be described.
The image input device 1 includes a scanner device using a CCD (charge coupled device) or a contact sensor, an A / D (analog / digital) conversion unit, an image processing unit, and the like. The image data is input to the image forming apparatus as a digital signal.
The display device 2 includes an LCD (liquid crystal display), a lamp, and the like, and displays various information of the digital copying apparatus. In addition, this display unit is provided with a pressure-sensitive or electrostatic touch panel, so that character input, menu selection, and the like can be directly performed on the display screen.
[0009]
The keyboard 3 includes number input keys, function keys, and the like, and a user performs data input using these keys.
The image printing device 4 includes a printer device for printing out image data processed by the digital copying device.
The CPU 5 is an arithmetic processing device that performs an image forming process according to a predetermined program. More specifically, various functions can be exhibited by reading a program from the ROM 6 or the RAM 7 into a storage unit called a register and operating according to the program.
[0010]
The ROM 6 is a memory that stores various programs, data, parameters, and the like for the CPU 5 to perform various calculations and controls. The CPU 5 can read programs, data, parameters, and the like from the ROM 6, but generally does not rewrite or delete them.
The RAM 7 is a memory used as a working memory by the CPU 5. The CPU 5 can write and erase programs and data in the RAM 7.
[0011]
Next, the operation of the image forming apparatus thus configured will be described.
FIG. 2 is a flowchart illustrating an operation procedure of an image forming process in the image forming apparatus according to the present embodiment.
First, a reading process of a document image is executed in the image input device 1 (step 11). More specifically, an original set on the original reading surface of the image forming apparatus is read using a CCD or a contact sensor provided in the image input device 1, and digital original image data is created based on the read data. .
Then, a show-through component removal process is performed on the digital document image data created by the document image reading process (step 12). Here, a process is performed to remove a show-through (back-side image appearing through) component included in the digital original image data. The detailed processing procedure of the show-through component removal processing will be described later.
[0012]
The user may determine in advance whether or not the original is a show-through based on the paper quality, thickness, and type of the original to be used, and select whether or not to execute the show-through component removal processing.
For example, in a color copying machine, before starting copying, a screen for setting whether or not an original is a show-through is displayed on the display device 2, and a user can select whether or not to show-through component removal processing. To do. The image processing apparatus accepts the user's selection and determines whether or not to execute the show-through component removal processing.
Since the processing method suitable for the document can be selected in this manner, the accuracy of the text / photo discrimination processing performed thereafter can be improved.
[0013]
Further, the user may be able to select the intensity of the show-through component removal processing in advance.
For example, in a color copying machine, before starting copying, a screen for selecting the degree of the show-through component removal processing is displayed on the display device 2 so that the user can select the degree of the show-through component removal processing. To The image processing apparatus accepts the user's selection, and executes show-through component removal processing based on the selected intensity.
Since the processing method suitable for the document can be selected in this manner, the accuracy of the text / photo discrimination processing performed thereafter can be improved.
[0014]
Character / photo discrimination processing is performed on the digital original image data from which show-through components have been removed by show-through component removal processing (step 13). Here, for each portion of the digital original image data, processing is performed to determine whether it is a character portion or a photograph (including a picture) portion. A detailed description of the text / photo determination processing will be described later.
[0015]
Next, a filtering process is performed on each portion of the digital original image data that has been separated into a character portion and a photo portion by the text / photo determination process (step 14).
More specifically, a portion determined as a character portion in the character / photograph determination process is set to a high UCR (under color removal) ratio to make black characters stand out, and is subjected to a one-pixel-one-dot process to increase resolution. You.
On the other hand, a portion determined to be a photograph portion is set to a low UCR ratio so as to have a tint, and is subjected to a smoothing process or the like for removing moire from a halftone dot document.
An image printing process is performed on the digital document image data that has been subjected to the filtering process (step 15), and the process ends. More specifically, digital document image data for forming an image (printing out) is transferred to the image printing device 4, and the image printing device 4 executes a printing process.
[0016]
FIG. 3 is a flowchart showing the operation procedure of the show-through component removal processing.
When color image data of a document is input by the image input device 1 (step 21), the CPU 5 performs a process of reducing the image data of the document (step 22). Here, by reducing the image data, it is possible to increase the speed of the subsequent various processes and to save the working memory to be used.
Next, the CPU 5 executes a process of converting the reduced image data into a color coordinate system (step 23).
[0017]
Subsequently, the CPU 5 executes a process of calculating the edge strength of the image data, calculates the edge strength (step 24), and performs a binarization process on the result (step 25). An edge portion in the image data is detected from the result of the binarization processing.
Then, a color threshold process is performed on the region excluding the detected edge portion (step 26). By executing the color threshold processing, it is possible to discriminate between the front surface and the show-through portion, and it is possible to specifically estimate the background color image.
Next, a show-through removal image is synthesized based on the background color image estimated by the color threshold processing (step 27).
[0018]
The CPU 5 calculates the edge strength of the show-through-removed image and calculates the edge strength (step 28). Based on the result, a difference in edge strength is calculated (step 29), and an edge difference image is generated.
Next, the CPU 5 performs a binarization process on the calculated difference between the edge intensities (step 30). Then, similarly to the processing of Step 26, the color threshold processing is executed again (Step 31), and the show-through removed image is synthesized (Step 32).
The CPU 5 calculates a difference between the show-through removed image and the reduced document image, and determines a show-through portion based on the calculation result (step 33).
Finally, at the original resolution, the show-through portion of the original image data is removed (step 34), and the process ends.
[0019]
Next, the text / photo determination process will be described.
The character portion has features such as "high contrast", "continuous black pixels", and "contiguous white pixels around".
In consideration of these features, the process of determining the character portion and the photograph portion can be executed as follows.
First, the image data is binarized using a predetermined threshold value and converted into black and white data. Then, the converted image data is compared with a preset pattern for determining a black edge and a white edge.
As a result of the comparison, when a predetermined number or more of matched patterns exist in the image data, the area is determined to be a character area.
If the number of matching patterns does not exceed a predetermined number in the image data, the area is determined to be a photograph area.
[0020]
When the background level is determined and the background density is high, the probability of the photograph portion is high. Therefore, the priority of the determination on the character side is reduced, or chromatic and achromatic colors are discriminated, and If it is determined that the character portion is a character portion, the probability that the character portion is a black character increases, so that the priority of determining the character portion may be increased.
According to the present embodiment, as described above, by removing the show-through component before performing the character / photograph determination process, it is possible to reduce erroneous determination of the character / photograph determination process due to show-through.
[0021]
【The invention's effect】
According to the first aspect of the present invention, by performing the character / photo discrimination processing on the image data from which the show-through component has been removed, it is possible to perform the character / photo processing with high accuracy without being affected by show-through. .
According to the second aspect of the present invention, by accepting the selection of the presence or absence of the show-through component removal process, it is possible to perform a highly accurate character / photo discrimination process suitable for a document.
According to the third aspect of the invention, by accepting the selection of the intensity of the show-through component removal processing, it is possible to perform highly accurate character / photo discrimination processing suitable for a document.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment.
FIG. 2 is a flowchart showing an operation procedure of an image forming process in the image forming apparatus according to the embodiment.
FIG. 3 is a flowchart showing an operation procedure of show-through component removal processing in the image forming apparatus according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image input device 2 Display device 3 Keyboard 4 Image printing device 5 CPU
6 ROM
7 RAM
8 Bus

Claims (3)

Image data creation means for reading an original image and creating image data;
From the image data created by the image data creating means, detecting means for detecting the intensity of the edge that is the boundary portion of the image,
Determining means for determining a background color image of the document image based on the intensity of the edge detected by the detecting means,
Removing means for removing show-through components from the image data based on the background color image determined by the determining means,
A show-through component-removed image data from which show-through components have been removed by the removing unit, and a comparison unit that compares predetermined pattern data,
Based on a comparison result obtained by the comparing means, a character photograph determining means for determining a character part and a photograph part of the show-through component removed image data,
Correction means for performing data correction processing for each part of the show-through component-removed image data based on the determination result obtained by the character / photo determination means;
Image forming means for printing the corrected image data subjected to the correction processing by the correction means, and forming an output image,
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, further comprising a removal processing receiving unit that receives a selection as to whether or not there is a show-through component removal process by the removal unit. The image forming apparatus according to claim 1, further comprising a removal processing intensity receiving unit configured to receive a selection of a processing intensity of the show-through component by the removing unit.

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