JP3911459B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention can be applied to an image forming apparatus capable of forming an image using an image forming medium, such as a digital color copying machine having a color copying function, a color printer function, a scanner function, and a facsimile function. The present invention relates to an image reading apparatus having a function.
[0002]
[Prior art]
With the spread of color image input devices such as color scanners, digital cameras, and digital color copies, document images such as books, magazines, catalogs, advertisements, and newspapers are now generally input in color. . These sentences and images are often printed on both sides of the paper, so when you copy the text and images, the back side image is seen through and mixed into the front side image. Occurs. Furthermore, in the case of a color sentence, when copied, the background color is often not uniform or a pattern, a pattern, a photograph, etc. are often mixed. For this reason, the problem of removing “show-through” from an image input by digital image processing has been considered difficult to handle, although it is necessary for improving the image.
[0003]
Due to the above circumstances, the show-through removal function of the conventional image reading apparatus reads the entire image on both the front and back sides of the document, determines the removal range based on the set image density, and The removal process was performed. Further, in the above-described show-through removal process, a high show-through removal effect can be expected as compared with other algorithms by using the “transfer sheet” algorithm disclosed in Japanese Patent Laid-Open No. 2002-1690.
[0004]
Further, as a conventional technique similar to the present invention, there is an image forming apparatus that removes show-through by taking the difference between a back image and a front image and removing the influence of the back image on the front surface (for example, a patent) Reference 1). There is also an image forming apparatus that reads out images on the front and back surfaces, determines an area that shows through on the opposite side by edge detection or brightness, and corrects the brightness of the area to remove show-through. (For example, refer to Patent Document 2). An image forming apparatus that inputs images of the front and back sides of a document, inverts either the front side image or the back side image, detects the position of each image, and removes the show-through according to the positional relationship. (For example, refer to Patent Document 3).
[0005]
[Patent Document 1]
JP 2001-313830 A (page 1-3, FIG. 4)
[Patent Document 2]
JP 2001-045297 A (page 1-2, FIG. 1)
[Patent Document 3]
JP 2000-22946 A (page 1-3, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, all of the show-through removal processing of the conventional image forming apparatus including the above-described conventional technology is based on the assumption that the detection of the front and back pixels is performed with high accuracy. Since it is difficult to accurately match the front surface and the back surface, there is a drawback in that show-through removal correction is performed on erroneous pixels, and the algorithm of the “transfer sheet” disclosed in JP-A-2002-1690 is used. In some cases, however, the show-through effect may be an unintentional show-through removal effect in which the show-through is not sufficiently removed or a portion other than the show-through is removed.
[0007]
In addition, since the show-through removal processing of the conventional image forming apparatus performs a complicated calculation on the entire back surface regardless of whether or not there is an image on the back side, depending on the removal level for the show-through, a heavy burden is placed on the processing device. There was also a problem of end up.
[0008]
The present invention has been made in view of the above circumstances, and is provided with a function of detecting in advance a portion where there is no image on the back side of the document, and by preventing the show-through removal processing from being performed on the detection range. Another object of the present invention is to provide an image reading apparatus capable of reducing the burden of the show-through removal process and obtaining a high precision show-through removal capability.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an image reading apparatus according to claim 1 scans a document surface, converts a document surface image into image data, receives image data on the back surface of the document from the reading device, and A recognizing unit for recognizing the back side image range; and a show- through removing unit for receiving the back side image range from the recognizing unit and performing a show- through removal process. Each of the scanning directions is divided into a plurality of areas, and the presence or absence of an image having a predetermined density or more is determined for each of the divided ranges, and the show-through removal unit is a range in which the recognition unit determines that there is an image having a predetermined density or more. This is characterized in that the show-through removal process is performed only on the.
[0010]
The image reading apparatus according to claim 2, wherein the image reading apparatus according to claim 1 is a medium capable of temporarily recording image data of document images on the front and back sides when reading both the front and back sides of the document. It is characterized by holding.
[0011]
The image reading apparatus according to claim 3 is characterized in that, in the image reading apparatus according to claim 1 or 2, the user can arbitrarily set the density used for determining the image range of the back surface.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 6 show an embodiment of the present invention.
[0015]
First, the basic algorithm of the present invention will be described with reference to FIG. 2 and FIG. FIG. 2 shows an example of a document to be read, and FIG. 3 shows a flowchart of the algorithm.
[0016]
For example, when a document having an image as shown in FIG. 2A and having an image as shown in FIG. 2B on the back side is scanned on the front side in FIG. 2A, the image shown in FIG. In this way, the image of FIG. 1B is transparent and overlaps with FIG.
[0017]
Therefore, first, FIG. 2B of the image on the back surface is read, and the read image is divided into arbitrary matrices as shown in FIG. 2D (FIG. 3, S101). It is determined in order one by one whether there is a pixel (FIG. 3, S102).
[0018]
If there is a pixel having a density G equal to or higher than a certain level (FIG. 3, S102 / YES), the matrix is registered as “with back image” (FIG. 3, S103). A region indicated by a hatched portion in FIG. 2D is a portion determined to be “with back image”. Then, the determination is performed in the same manner as described above for the next order matrix (FIG. 3, S104). Even when there is no pixel having a density G higher than a certain level, the next matrix is determined (FIG. 3, S104).
[0019]
The above determination is performed for all the matrices (FIG. 3, S105 / NO). When the determination of all the matrices is completed (FIG. 3, S105 / YES), in the image of FIG. 2C, only the hatched portion shown in FIG. Perform removal processing.
[0020]
As described above, according to the algorithm of the present invention, for example, correction processing is not performed in a region other than the shaded area in FIG. 2E, so that the processing load can be reduced. In addition, since the correction process is not performed on the portion of the back surface where there is no image, it is possible to prevent image deterioration in a portion where the process is not performed.
[0021]
Next, a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. A document reading apparatus 1 that scans a document surface and converts an image on the document surface into electrical image data. The back side image range determination device 2 that receives the back side image data from 1 and recognizes the back side image area, and the back side image range received from the back side image range determination device 2 with respect to the image data received from the document reading device 1 A show-through removal device 3 for performing a copy-removal process, an image output device 4 for outputting an image obtained by image correction, a user interface 5 for communicating with a user, and a controller 6 for controlling the above-mentioned units in an integrated manner Have The show-through removal apparatus 3 corrects image data by using an algorithm disclosed in Japanese Patent Laid-Open No. 2001-1690.
[0022]
Next, the operation of the image forming apparatus according to the first embodiment will be described with reference to FIG. First, when the user interface 5 recognizes an instruction to start reading a document, the controller 6 instructs the document reading device 1 to read the back side of the document, and the document reading device 1 reads the image on the back side (FIG. 4, FIG. 4). S201).
[0023]
Then, the document reading device 1 converts the read image into image data and sends it to the back image range determination device 2. The back image range determination device 2 determines a portion of the back image (FIG. 4, S202), and notifies the show-through removal device 3 of the back image range.
[0024]
Further, a front surface reading instruction is issued from the controller 6 to the document reading device 1, and the document reading device 1 reads an image on the surface of the document (FIG. 4, S203). Then, the read image is converted into image data and sent to the show-through removal device 3.
[0025]
The show-through removal device 3 performs a show-through removal process on the sent back image data range instructed from the back image range determination device 2 (S204 in FIG. 4). After the removal process, the processed image data from which the show-through has been removed is sent to the image output device 4 and output (S205 in FIG. 4).
[0026]
As described above, according to the image forming apparatus according to the embodiment of the present invention, the correction process can be performed only on a portion where the image is on the back surface. A removed image can be obtained.
[0027]
Next, as a second embodiment, FIG. 2, FIG. 5 and FIG. 5 illustrate operations when the above-described image forming apparatus reads a manuscript whose front and back surfaces are printed in order. This will be described with reference to FIG. 2 shows an example of a document to be read, FIG. 5 shows the configuration of the image forming apparatus, and FIG. 6 shows the operation of the image forming apparatus.
[0028]
For example, when reading both sides of a document having images as shown in FIG. 2A on the front side and FIG. 2B on the back side, if the user interface 5 recognizes an instruction to start reading the document, the controller 6 instructs the document reading apparatus 1 to read the surface of the document. The document reading device 1 reads the front image (FIG. 6, S301), converts the read image into image data, and sends the image data to the back image range determination device 2.
[0029]
The back image determination device 2 recognizes the image data as the back surface for the image of FIG. 2B, and determines the image range (FIG. 6, S302). After the determination, the image data is temporarily held in the image storage device 7 (FIG. 6, S303).
[0030]
When the reading of the front image is completed, the controller 6 instructs the document reading apparatus 1 to read the back image. The document reading device 1 reads an image on the back side (FIG. 6, S304), converts the read image into image data, and sends the image data to the back side image range determination device 2. The back surface image range determination device 2 determines the image range using the back surface image data as the back surface in FIG. After the determination, the image data is held in the image storage device 7 (S305 in FIG. 6).
[0031]
When the determination of the image data in FIG. 2B is completed, the image data on the surface of the document held in the image storage device 7 is sent to the show-through removal device 3 according to an instruction from the controller 6. The show-through removal device 3 performs a show-through removal process on the sent image data for the range indicated by the oblique lines in FIG. 2 (f) (FIG. 6, S306), and the image output device 4 has already processed it. Send image data. When the front-side image output is completed (FIG. 6, S307), this time, the image on the back side of the document shown in FIG. 2B is sent to the show-through removal device 3, and is indicated by the oblique lines in FIG. The show-through removal process is performed on the range (FIG. 6, S308), and the image output apparatus 4 outputs the result (FIG. 6, S309).
[0032]
As described above, according to the image forming apparatus according to the embodiment of the present invention, the image read for the determination of the first back side image is once stored in the image storage device such as a memory, and the surface is read. By determining the image as a back side image with respect to the back side this time, by reducing the number of readings, it is possible to obtain an image that has been subjected to efficient and accurate back side removal processing.
[0033]
In the first and second embodiments, the user can freely set the image density level G for determining the presence or absence of the back image. Since the degree of show-through is determined by the paper quality of the document, for example, in a document with a low degree of show-through, if G is increased, the expected range of show-through can be reduced. It can be reduced, and the processing load can be reduced.
[0034]
【The invention's effect】
According to the image reading apparatus of the present invention, a scanning unit that scans a document surface and converts an image on the document surface into image data, and recognition that receives image data on the back side of the document from the scanning unit and recognizes an image range on the back side And a show- through removal unit that receives a back-side image range from the recognition unit and performs a show- through removal process, and the recognition unit divides the read image data into a plurality of parts in each of the main operation direction and the sub-scanning direction. Then, for each divided range, the presence or absence of an image having a predetermined density or more is determined, and the show-through removal means performs the show-through removal processing only for the range determined by the recognition means to have an image having the predetermined density or more. Therefore, the burden on processing can be reduced, and accurate show-through removal capability can be obtained.
[0035]
According to the image reading apparatus of the present invention, in the image reading apparatus, since when reading both sides of a document is characterized in that retaining the medium for recording temporarily image data of the surface and the back surface of the image, The burden of processing can be reduced without reducing the show-through removal capability, and an image with accurate show-through removal can be efficiently obtained.
[0036]
According to the image reading apparatus of the present invention, in the image reading apparatus, since the concentration used for the determination of the back surface of the image area the user is characterized by be arbitrarily set, bleed-through reduction in the optimal range of the type of document Processing can be performed, the burden on processing can be reduced, and an image with accurate show-through removal can be obtained efficiently.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a document printed on both sides.
FIG. 3 is a flowchart showing an algorithm of the present invention.
FIG. 4 is a flowchart showing a first embodiment of the present invention.
FIG. 5 is a block diagram illustrating an internal configuration of an image forming apparatus according to a second embodiment of the present invention.
FIG. 6 is a flowchart showing a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Document reading apparatus 2 Back surface image range determination apparatus 3 See-through removal processing apparatus 4 Image output apparatus 5 User interface 6 Controller 7 Image storage apparatus

Claims (3)

Scanning means for scanning a document surface and converting the image on the document surface into image data;
Recognizing means for receiving image data of the back side of the original from the reading means and recognizing the image range of the back side;
A show-through removal unit that receives the image range of the back surface from the recognition unit and performs a show-through removal process;
The recognizing unit divides the read image data into a plurality for each of the main operation direction and the sub-scanning direction, determines the presence or absence of an image having a predetermined density or more for each divided range,
The image reading apparatus according to claim 1, wherein the show-through removal unit performs the show-through removal process only on a range in which the recognition unit determines that there is an image having a predetermined density or more .   2. The image reading apparatus according to claim 1, wherein when reading both sides of a document, the images on the front and back sides are temporarily held on a medium for recording image data. The image reading apparatus according to claim 1, wherein a user can arbitrarily set the density used for determining the image range of the back surface.

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