JP2008022275A - Image processing apparatus, program, and recording medium - Google Patents

Abstract

An image processing apparatus and the like that can automatically adjust a blank sheet detection level automatically using a document that is actually detected as blank paper or a document that is not detected as blank paper.
A scanner unit 201 serving as an image input unit that reads a document and generates read image data, an image processing unit that performs image processing on the read image data, an image storage 203 that stores the read image data, and It has a blank sheet detection 202 for detecting that a document is blank from the read image data, and the blank sheet detection 202 is automatically adjusted from the read image data.
[Selection] Figure 2

Description

  The present invention relates to an image processing apparatus in a digital copying machine, a scanner device, a printer device, a facsimile device, or a digital multifunction machine having these functions.

  There is a copying machine (image reading apparatus) having a function of detecting and notifying a user when a blank original is erroneously read due to a mistake in setting the front and back of the original. However, it is difficult to appropriately adjust the detection level in order to prevent erroneous detection such that a document that is not a blank document is detected as a blank document or a blank document cannot be detected.

As a method for determining whether or not the correct side of the document has been read using the image processing function, a method called “blank paper detection” is generally used. For example, Patent Document 1 (image processing apparatus) and Patent Document 2 are used. There have been proposals such as (blank paper detection method and image information processing apparatus using this method). The sensitivity of blank sheet detection in these methods is adjusted by setting a threshold value or the like, but it is difficult to appropriately adjust the blank sheet detection level.
JP 2003-198777 A JP 2000-287024 A

  In view of the above circumstances, an object of the present invention is to provide an image processing apparatus and the like that can automatically perform appropriate adjustment of a blank sheet detection level using a document that is actually detected as blank paper or a document that is not desired to be detected as blank paper. And

  An aspect of the present invention that achieves the above object includes an image input unit that reads a document and generates read image data, an image processing unit that performs image processing on the read image data, and an image storage unit that stores the read image data. A blank sheet detecting unit that detects that the original is blank from the read image data, and a unit that automatically adjusts the blank sheet detecting unit from the read image data. Is.

  Here, the blank sheet detecting means detects that the document is blank from the read image data based on a density threshold value and a pixel count threshold value.

  And a means for selecting a blank sheet detection adjustment level to be used at the time of blank sheet detection from a plurality of blank sheet detection adjustment levels, and a means for automatically generating a plurality of blank sheet detection adjustment levels from the read blank image data. To do.

  The image processing apparatus further comprises means for automatically generating a blank level detection density level threshold value from the read blank page image data. The image processing apparatus further includes means for automatically generating a pixel count level threshold value for blank sheet detection from the read blank sheet image data.

  Further, the present invention is characterized in that it has means for generating a blank sheet detection adjustment level at a constant interval centering on the level of the read image data of the blank sheet.

  Furthermore, it has a means for manually adjusting a blank sheet detection adjustment level automatically generated from the read image data of blank sheet.

  According to another aspect of the present invention, an image input unit that reads a document and generates read image data, an image processing unit that performs image processing on the read image data, and an image storage unit that accumulates the read image data are stored in a computer. An image processing apparatus that functions as a blank sheet detecting unit that detects that a document is blank from the read image data and functions as a unit that automatically adjusts the blank sheet detecting unit from the read image data. Is related to the program.

  Another aspect of the present invention relates to a recording medium on which the program is recorded.

  The image processing apparatus according to the present invention can automatically perform appropriate adjustment of the blank sheet detection level by actually reading a document that is actually detected as blank paper or a document that is not desired to be detected as blank paper. Is possible.

  Hereinafter, the best mode for carrying out the image processing apparatus of the present invention will be described. In the description, the drawings submitted at the same time as this specification will be referred to as appropriate.

FIG. 1 shows a block diagram of the entire apparatus for carrying out the present invention.
The image input unit 101 corresponds to a digital copy or digital facsimile scanner, reads an original, generates read image data that is image data relating to the read original, and sends the read image data to the image processing unit 102.
The image processing unit 102 performs various image processing such as blank sheet detection, MTF filter processing, γ correction processing, and gradation processing on the read image data, and sends the image data to the image output unit 103.
The image output unit 103 corresponds to a printer of a digital copying machine, and prints out image data after image processing on paper.
The image storage unit 104 stores the image data read from the original, and reads out the image data stored at the time of image processing or printing.
The control unit 105 performs overall control of the apparatus. The image input unit 101 performs scanner operation control, and the image processing unit 102 sets parameters used for various image processing such as blank sheet detection, MTF filter processing, γ conversion processing, and gradation processing. The image output unit 103 is controlled to operate the printer, the image storage unit 104 is controlled to store, read, and erase, and the operation unit 106 is controlled to display various information. And input control of operation mode.
The operation unit 106 is used for selecting an operation mode set by the user, inputting a copy start instruction, and displaying a notification to the user.

  FIG. 2 shows a detailed block diagram of the present invention. The present invention controls a scanner unit 201 that reads a document image, a blank page detection 202, an MTF filter process 204, a γ conversion process 205, a gradation process 206, a printer unit 207 that outputs an image as a copy, an image storage 203, and control of the entire apparatus. A CPU (Central Processing Unit) 209 to be executed, a ROM (Read Only Memory) 210 in which a control program is stored, a RAM (Random Access Memory) 211 temporarily used by the control program, and exchange of data between the devices. The system bus 208 includes an operation unit 212 that gives instructions such as operation mode selection, start, and stop, and displays a setting state.

  The correspondence between FIG. 1 and FIG. 2 is as follows. The scanner unit 201 corresponds to the image input unit 101. The image processing unit 102 corresponds to blank sheet detection 202, MTF filter processing 204, γ conversion processing 205, and gradation processing 206. The printer unit 207 corresponds to the image output apparatus 103. An image storage 203 corresponds to the image storage unit 104. The CPU 209, the ROM 210, and the RAM 211 correspond to the control unit 105. An operation unit 212 corresponds to the operation unit 106.

  A specific operation of the embodiment of the present invention will be described. The present invention includes a blank sheet detection operation when reading a document and an automatic adjustment operation of a detection level used for the blank sheet detection. First, a blank sheet detection operation when reading a document will be described with reference to FIGS.

  FIG. 3 shows an operation for setting detection parameters for the blank sheet detection 202 before reading the document. In the blank sheet detection 202, a density threshold value and a pixel count threshold value are set through the system bus 208. Similarly, a filter coefficient is set for the MTF filter processing 204, a γ characteristic data for the γ conversion processing 205, a multi-value threshold value for the gradation processing 206, and the like are set through the system bus 208.

  FIG. 4 shows the flow of image data during document reading. The image data read by the scanner unit 201 is sent to the image processing unit. In the image processing unit, the blank sheet detection 202 detects whether the sheet is blank or non-blank from the image data, and sends it to the image storage 203 for storage.

  The internal configuration of the blank paper detection 202 is shown in FIG. A density threshold value is set in the comparator 301 from the system bus 208 and is compared with the read image data. When the read image data is a pixel having a density threshold value or more, it is counted by the counter 302. A pixel count threshold value is set in the comparator 303 from the system bus 208, and the count value of the counter 302 is compared. When the count value of the counter 302 is less than the pixel count threshold value, it is detected as blank paper, and when it is equal to or greater than the pixel count threshold value, it is detected as non-blank paper and sent to the system bus 208 as a blank paper detection result.

  FIG. 5 shows an operation of acquiring a blank page detection result from the blank page detection 202 of the system bus 208 after reading the document. The control unit 105 reads the blank page detection result of the blank page detection 202. The ROM 210 in the control unit 105 stores a control program that changes the image processing operation in accordance with the read blank sheet detection result. Depending on the control program, the blank page detection result is displayed, or the next operation instruction screen is displayed on the operation unit 212 to notify the operator.

  FIG. 6 shows an operation in which the image data stored in the image storage 203 is read and sent to the image processing unit 102. In the image processing unit 102, various image processing such as MTF filter processing 204, γ conversion processing 205, and gradation processing 206 is performed and sent to the printer unit 207. The MTF filter processing 204, the γ conversion processing 205, and the gradation processing 206 are general image processing that can be realized by the conventional technology. Execution of the reading operation from the image storage 203 is determined by the blank sheet detection result.

  Next, the automatic adjustment operation of the detection level used in the blank sheet detection of the present invention will be described. FIG. 11 shows a display screen of the operation unit 212 when setting the blank sheet detection level. On this screen, the density level threshold value and the pixel count level threshold value used as the blank page detection parameters can be selected and adjusted from preset values in five stages. The level is selected from level 1 that is easily detected as blank paper to level 5 that is difficult to detect. In the example of FIG. 11, the density level threshold is set to level 2 and the pixel count level threshold is set to level 4. A blank sheet detection operation is performed with this set value.

  The density level threshold value and the pixel count threshold value in FIG. 11 can be automatically adjusted individually. When the automatic adjustment of the density level is selected on the screen of FIG. 11, the screen of FIG. 12 is obtained, and when the automatic adjustment of the pixel count level is selected, the screen of FIG. 13 is obtained.

  On the density level adjustment screen shown in FIG. 12, specific threshold values for five preset density levels are displayed. In the example of FIG. 12, level 1 = 0, level 2 = 4, level 3 = 8, level 4 = 12, and level 5 = 16 are set. Here, the threshold value set for each level can be manually changed. When a level to be changed is selected and a threshold value to be changed is input, the threshold value of the level is changed.

  In FIG. 12, in order to automatically adjust the density level threshold value, a blank original used for adjustment is set and automatic adjustment start is selected. A blank original is read by the scanner unit 201 and stored in the image storage 203 in the image data flow shown in FIG.

  The image data stored in the image storage 203 is read through the system bus 208 and used to adjust the density level threshold value. FIG. 8 shows an example of the density distribution of image data stored in the image storage 203 when a blank original is read. The relationship between the density level and the number of pixels read at the density level is shown. Even when a blank sheet is read, the read value is not completely zero, and a density level distribution is generated according to the background density of the blank document.

  FIG. 9 shows a flow for automatically adjusting the density level threshold value from the read image data of the blank original. First, the pixel count threshold Cth is set (S01), and the pixel count integrated value Csum is set to 0 (S02). Next, from the density level i = 255, the pixels existing at the density level are added to Csum (S03, S04). When Csum becomes larger than Cth (Yes in S05), i at that time is adjusted. The set density level threshold value Nth is set (S09). If Csum does not become larger than Cth even after adding pixels until i = 0 (No in S05), the density level threshold Nth = 0 is set (S06 to S08).

The automatically adjusted density level threshold value Nth is set as the value of the central level 3 of the five levels, and each of the five levels is set as follows at a constant interval α.
Level 1 = Nth-2 x α
Level 2 = Nth-α
Level 3 = Nth
Level 4 = Nth + α
Level 5 = Nth + 2 x α

  If automatic adjustment of the pixel count level is selected on the screen of FIG. 11, the screen of FIG. 13 is displayed. In the pixel count level adjustment screen of FIG. 13, specific threshold values of five preset pixel count levels are displayed. In the example of FIG. 13, level 1 = 800, level 2 = 600, level 3 = 400, level 4 = 200, and level 5 = 100 are set. Here, the threshold value set for each level can be manually changed. When a level to be changed is selected and a threshold value to be changed is input, the threshold value of the level is changed.

  In FIG. 13, when the threshold value of the pixel count level is automatically adjusted, a blank original used for adjustment is set and automatic adjustment start is selected. A blank original is read by the scanner unit 201 and stored in the image storage 203 in the image data flow shown in FIG.

  The image data stored in the image storage 203 is read through the system bus 208 and used to adjust the pixel count level threshold value. FIG. 10 shows a flow for automatically adjusting the pixel count level threshold value from the read image data of the blank original. First, the density threshold value Nth is set (S01), and the pixel count integrated value Csum is set to 0 (S02). Next, from the density level i = 255, while i is Nth or more, the pixels existing at the density level are added to Csum (S03 to S06). The addition result Csum is set as a pixel count threshold Cth (S07).

The automatically adjusted pixel count level threshold value Cth is set as the value of the center level 3 of the five levels, and the respective levels of the five levels are set as follows at a constant interval β.
Level 1 = Cth + 2 x β
Level 2 = Cth + β
Level 3 = Cth
Level 4 = Cth-β
Level 5 = Cth-2 × β

  By implementing this embodiment, the following effects can be obtained. In other words, the blank document detection function has the problem of false detections such as detecting a document that is not a blank document as a blank document or being unable to detect a blank document. Although difficult, the present invention can automatically perform appropriate adjustment of the blank sheet detection level by using a document that is actually detected as a blank sheet or a document that is not desired to be detected as a blank sheet and actually reading them. There is an effect that it becomes possible.

  Further, by using the density level of the image and the level of the number of pixels equal to or higher than the density level as the blank page detection level adjusting means, it is possible to easily perform appropriate automatic blank page detection level.

  Further, since the most appropriate blank sheet detection level can be selected from a plurality of automatically adjusted blank sheet detection levels, it is possible to easily adjust the more accurate blank sheet detection level.

  Further, it is possible to automatically adjust the blank sheet detection level appropriately by reading a blank document and automatically adjusting the density level used for blank sheet detection from the read image data.

  In addition, it is possible to automatically perform appropriate adjustment of the blank sheet detection level by scanning a blank document and automatically adjusting the pixel number level above a certain density level used for blank sheet detection from the read image data. Is possible.

  In addition, by automatically generating multiple blank page detection levels at regular intervals around the density level and pixel count level adjusted by scanning blank pages, you can select the most appropriate blank page detection level from among them. It is possible to easily adjust the white paper detection level with high accuracy.

  Further, it is possible to easily adjust the white paper detection level with higher accuracy by manually adjusting the density level and the pixel count level, which are automatically adjusted by reading the white paper, as necessary.

  The above-described embodiment is the best for carrying out the image processing apparatus of the present invention, but is not intended to be limited to such an embodiment. Therefore, various modifications can be made to the implementation form without departing from the scope of the present invention.

It is a block diagram of the whole apparatus of this form. It is a detailed block diagram of this form. FIG. 6 is a block diagram illustrating setting of blank sheet detection parameters before document reading. FIG. 3 is a block diagram illustrating a flow of image data from reading a document to storing an image. It is a block diagram in a state where a control unit is reading a blank sheet detection result. 6 is a block diagram illustrating a flow of image data from reading of an accumulated image to a printer unit 207. FIG. FIG. 6 is a detailed block diagram of the inside of a blank paper detection 202. It is an example of the density distribution of image data stored in the image storage 203 when a blank original is read. It is a flowchart when the density threshold value is automatically adjusted. It is a flowchart when adjusting a pixel count threshold value automatically. It is a display example of the operation unit 212 in the “blank paper detection level setting” state. It is a display example of the operation unit 212 in the “density level adjustment” state. It is a display example of the operation unit 212 in the “pixel count level adjustment” state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image input part 102 Image processing part 103 Image output part 104 Image storage part 105 Control part 106 Operation part 201 Scanner part 202 Blank paper detection 203 Image storage 204 MTF filter process 205 Gamma conversion process 206 Gradation process 207 Printer part 208 System bus 209 CPU
210 ROM
211 RAM
212 Operation Unit 301 Comparator 302 Counter 303 Comparator

Claims (9)

Image input means for reading a document and generating read image data;
Image processing means for image processing the read image data;
Image storage means for storing the read image data;
A blank sheet detecting means for detecting that the document is blank from the read image data;
An image processing apparatus comprising: means for automatically adjusting the blank sheet detecting means from the read image data. The blank sheet detecting means includes
2. The image processing apparatus according to claim 1, wherein it is detected from the read image data that the original is a blank sheet based on a density threshold value and a pixel count threshold value. Means for selecting a blank sheet detection adjustment level to be used for blank sheet detection from a plurality of blank sheet detection adjustment levels;
The image processing apparatus according to claim 2, further comprising means for automatically generating a plurality of blank sheet detection adjustment levels from the read blank sheet image data.   4. The image processing apparatus according to claim 3, further comprising means for automatically generating a density level threshold value for blank sheet detection from the read blank sheet image data.   4. The image processing apparatus according to claim 3, further comprising means for automatically generating a pixel count level threshold value for blank sheet detection from the read blank sheet image data.   6. The image processing apparatus according to claim 4, further comprising means for generating a blank sheet detection adjustment level at regular intervals centered on a level of blank sheet read image data.   7. The image processing apparatus according to claim 6, further comprising means for manually adjusting a blank sheet detection adjustment level automatically generated from the read image data of blank sheet. On the computer,
Image input means for reading a document and generating read image data;
Image processing means for image processing the read image data;
Image storage means for storing the read image data;
Function as blank sheet detecting means for detecting that the document is blank from the read image data,
A program for an image processing apparatus that causes a function of automatically adjusting the blank sheet detecting means from the read image data.   A recording medium on which the program according to claim 8 is recorded.

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