JP3611407B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus that reduces the consumption of a recording material while suppressing deterioration in image quality and character readability.
[0002]
[Prior art]
A function that suppresses the consumption of recording material (hereinafter referred to as “econo mode”) is installed in most image processing apparatuses such as printers and facsimile machines, and is used for output of received images, output of printers, and output of copies of facsimile machines. It is used to reduce the consumption of a recording material, for example, toner.
[0003]
As a conventional image processing apparatus equipped with such an econo mode, for example, there is an electrophotographic printer apparatus disclosed in JP-A-2-144574, and this printer apparatus is designated with a toner saving mode. The toner consumption is reduced by thinning out the dot data of the image portion.
[0004]
Such thinning processing generally includes an image processing circuit 1 as shown in FIG. 48, and the image processing circuit 1 includes a thinning processing unit 2, an edge detection unit 3, an OR circuit 4, and the like. That is, input image data read by a scanner or the like is input to the thinning processing unit 2 and the edge detection unit 3 of the image processing circuit 1, and when the input image data is a monochrome binary image, black is “1”. In the case of a binary image in which white is “0” and a color or monochrome gray scale, image processing is performed on the binary image in advance.
[0005]
The edge detection unit 3 and the thinning processing unit 2 operate according to a timing signal that gives the coordinates (x, y) of each pixel, and perform a thinning process using a bit pattern as shown in FIG. 49, for example.
[0006]
For example, the thinning-out processing unit 2 determines that the pixel coordinates of the coordinates (x1, y1) are x1 = y1 = odd number or even number (in FIG. 49, x1 = y1 = 0, x1 = y1 = 1). Black), a black pixel “1” signal is output, and a white “0” signal is output to the OR circuit 4 otherwise. The edge detection unit 3 outputs a signal of “1” to the OR circuit 4 when it is an edge and “0” when it is not an edge. The OR circuit 4 calculates the logical sum of the output from the thinning processing unit 2 and the output from the edge detection unit 3 and outputs the result as output image data to an electrophotographic image forming process or the like. Therefore, the OR circuit 4 outputs the output image data in which the pixels in the edge portion remain black and the black pixels other than the edge portion have a halftone dot pattern.
[0007]
[Problems to be solved by the invention]
However, in such a conventional image processing apparatus, the thinning process is performed on the black pixels in order to reduce the toner consumption in the econo mode, so that the readability (readability) of the character image is remarkably high. There is a problem that the image quality of the copy output deteriorates. In particular, in the generation copy (copy using the output in the eco mode as a manuscript), although depending on the characteristics of the image forming process, dot thinning and dot omission occur in the thinning pattern, and the image is further deteriorated.
[0008]
That is, when the toner reduction process is performed by the conventional thinning process, for example, the thinning process is performed on the input image shown in FIG. 50 using the thinning bit pattern shown in FIG. As shown in FIG. 50, thinning processing is performed on the entire black area of the input image, and the entire image becomes blurred as shown in FIG. 50, and the readability in the case of a character image deteriorates, and the image quality deteriorates. There was a problem to do.
[0009]
Accordingly, the invention according to claim 1 detects the edge of the black area of the image and deletes the edge of the black area by a predetermined amount, so that the character can be deleted without performing the conventional thinning process of the black area. Image processing apparatus capable of reducing recording material consumption while maintaining good readability and good image quality during copyingAndProvided is an image processing apparatus capable of appropriately selecting a balance between character readability and image quality and recording material consumption by deleting an edge of a black region of an image by an amount according to an instruction of an edge cutting amount instruction means. The purpose is that.
[0010]
Claim2The described invention detects the connectivity of the black area of the image and controls the deletion amount of the edge of the black area of the image. An object of the present invention is to provide an image processing apparatus capable of reducing the consumption of a recording material while further improving character readability and image quality by preventing cutting or blurring.
[0011]
[Means for Solving the Problems]
Invention of Claim 1The operation of the imaging material saving mode, in which a part of the black pixels of the original image data to be processed is deleted and an image is recorded on the recording paper using the imaging material based on the deleted image data. An image processing apparatus capable of performing deletion of original image data by a deletion amount instruction means for instructing a deletion amount of a black pixel, and a pixel matrix process with a condition corresponding to the deletion amount instructed by the deletion amount instruction means. Edge detection means for performing processing for detecting an edge of a target black pixel area, and means for deleting the edge of the black pixel area detected by the edge detection means from the original image dataBy providing, the above object is achieved.
[0012]
According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the presence or absence of connectivity with surrounding black pixels of black pixels of the original image data to be processed is determined by pixel matrix processing. The above object is achieved by further comprising connectivity determination means and deletion control means for operating the edge deletion means on the condition that the determination result of the connectivity determination means is no connectivity.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description which limits, it is not restricted to these aspects.
[0014]
1 to 6 show an image processing apparatus according to the present invention.The figure explaining basic composition and a processing method based on an embodimentIt is. FIG. 1 is a circuit block diagram of a facsimile machine 10 to which the present invention is applied.
[0015]
In FIG. 1, a facsimile machine 10 includes a reading scanning unit 11, a reading processing unit 12, a recording scanning unit 13, a recording processing unit 14, a line memory 15, a line memory control unit 16, an information compression / decompression unit 17, a modem 18, and a communication. A control unit 19, a network control unit 20, a DMA controller 21, a ROM 22, an MPU 23, a RAM 24, an interface 25, a mechanism control unit 26, an interface 27, a panel unit 28, and the like are provided. Each unit includes a data bus and an address bus. Connected by a bus 29.
[0016]
For example, a line image scanner using a CCD (Charge Coupled Device) or the like is used as the reading scanning unit 11, and the reading scanning unit 11 operates under the control of the reading processing unit 12 to obtain an image of a document. Read at a resolution of. The reading processing unit 12 operates under the control of the MPU 23 to control the driving of the reading scanning unit 11 and transfers image data read by the reading scanning unit 11 to the line memory 15 via the bus 29.
[0017]
The recording scanning unit 13 uses, for example, an electrophotographic recording device, and records and outputs a toner image on recording paper based on image data transferred from the line memory 15 via the line memory control unit 16. . The recording processing unit 14 operates under the control of the MPU 23 to drive and control the recording processing unit 13 to record and output an image on recording paper.
[0018]
The line memory 15 stores the image data encoded by the information compression / decompression unit 17 or the image data read by the reading scanning unit 11 or the like for each line. The line memory control unit 16 operates under the control of the MPU 23, and controls writing of image data to the line memory 15 and reading of image data from the line memory 15.
[0019]
The information compression / decompression unit 17 is for improving the efficiency of storing image data and shortening the transmission time. The information compression / decompression unit 17 encodes the image data according to a predetermined encoding method, and also converts the encoded image data. Decrypt.
[0020]
The network control unit 20 is connected to a line L, for example, a public telephone line or a dedicated line. The network control unit 20 automatically receives a call from the line L, and automatically issues a call to the line L. Perform call processing. The modem 18 is connected to the network control unit 20 and operates under the control of the MPU 23 to modulate the transmission signal and the reception signal. The communication control unit 19 exchanges facsimile control signals with the partner facsimile machine and executes a facsimile communication procedure.
[0021]
A DMA (Direct Memory Access) controller 21 directly transfers data between the input / output device and the memory or between the memories without going through the MPU 23.
[0022]
A ROM (Read Only Memory) 22 stores a basic processing program as the facsimile apparatus 10 and an image processing program to be described later, and system data and other various data necessary for executing these processing programs. Is stored in advance.
[0023]
An MPU (Micro Processing Unit) 23 controls each part of the facsimile apparatus 10 based on a program in the ROM 22 to execute basic processing as the facsimile apparatus 10 and also performs image processing to be described later. In particular, the MPU 23 has an econo mode for reducing the toner consumption when the toner image is recorded by the recording scanning unit 13, and the image processing in the econo mode, that is, the edge detection process of the black area of the image data, the edge By performing edge deletion processing based on the detection result, black region connectivity determination processing, edge deletion control processing based on the black region connectivity determination processing, and the like, toner consumption in the recording scanning unit 13 is reduced.
[0024]
A RAM (Random Access Memory) 24 is used as a reception buffer, a transmission buffer, a work memory of the MPU 23, etc., and temporarily stores reception image data and transmission image data, and temporarily stores calculation results of the MPU 23 and the like.
[0025]
The mechanism control unit 26 is a generic term for various drivers, sensors, and the like, and is connected to the bus 29 via the interface 25. The panel unit 28 is a general term for an operation unit, a display unit, and the like provided with keys and switches of the facsimile apparatus 10, and is connected to the reading processing unit 12 through the interface 27 and through the interface 25. It is connected to the bus 29. The panel unit 28 is provided with a mode switching key for setting / releasing the eco mode, an edge cutting amount instruction key (edge cutting amount instruction means) for instructing an edge cutting amount in the eco mode, and the like. In accordance with the key setting state of the mode switching key, the eco mode process or the normal mode process is performed, and the edge deletion process of the black area of the image data is performed in the eco mode by the amount according to the instruction of the edge cutting amount instruction key. .
[0026]
Next, the operation of the present embodiment will be described. In the facsimile apparatus 10, during transmission, the MPU 23 controls the reading scanning unit 11 via the reading processing unit 12, reads an image of a document, and temporarily reads the image data of the document via the reading processing unit 12. Remember me. The MPU 23 removes redundancy while reading out image data from the line memory 15 according to the compression mode of the information compression / decompression unit 17, and temporarily stores it in the RAM 24 via the bus 29. The facsimile apparatus 10 uses the RAM 24 as a transmission buffer, sequentially transfers the image data to the modem 18 via the communication control unit 19, modulates it with the modem 18, and then transmits it to the line L via the network control unit 20. Send it out. Further, at the time of reception, the facsimile apparatus 10 transfers the received image data to the information compression / decompression unit 17 using the RAM 24 as a reception buffer via the network control unit 20 and the communication control unit 19, and compresses / decompresses the information. Decoded (restored) by the unit 17 and temporarily stored in the line memory 15. The facsimile apparatus 10 transfers the image data in the line memory 15 to the MPU 23 as necessary, performs various image processing, and stores the image data in the line memory 15 again. Thereafter, the facsimile apparatus 10 transfers the image data from the line memory 15 to the recording processing unit 14 and causes the recording scanning unit 13 to record and output the toner image on the recording paper.
[0027]
As one of the contents of the image processing in the MPU 23, the facsimile apparatus 10 sets the image data image by the amount specified by the edge cutting amount instruction key when the eco mode is set by the mode switching key of the panel unit 28. Image processing is performed to delete the edge of the black area.
[0028]
That is, as shown in FIG. 2, the MPU 23 includes an image processing circuit 30 in software or hardware, and the image processing circuit 30 includes an edge detection unit 31 and an AND circuit 32. Note that the output of the edge detector 31 is inverted and input to the AND circuit 32. Image data (input image data) is input from the line memory 15 to the edge detection unit 31 and the AND circuit 32 of the image processing circuit 30, and the output of the edge detection unit 31 is further input to the AND circuit 32. . The input image data is binary image data in which the black pixel is “1” and the white pixel is “0”.
[0029]
The edge detection unit (edge detection means) 31 detects whether or not the input image data is an edge region of a black region. When the input image data is an edge portion, “1” is input. When the input image data is a non-edge portion, “0” is input. Output to the circuit 32. The edge detection processing by the edge detection unit 31 may detect the edge of the black region by any method as long as it can appropriately detect the edge of the black region of the image of the image data. For example, 31 performs edge detection processing using a 3 × 3 matrix as shown in FIG. That is, the edge detection unit 31 sets the hatched center pixel of the nine matrix pixels in FIG. 3 as a target pixel, and when the target pixel is a black pixel, When the image data is examined and one or more white pixels are present in the surrounding pixels, it is determined that the target pixel is an edge pixel.
[0030]
The edge detection process by the edge detection unit 31 is shown in a flowchart in FIG. That is, the edge detection unit 31 performs matrix processing on the input image data sequentially input from the line memory 15 and checks whether the target pixel is a black pixel (step S1). If it is determined in step S1 that the pixel of interest is not a black pixel, it is determined that the pixel of interest is a non-edge pixel, “0” is output to the AND circuit 32, and the edge detection processing for the pixel of interest is terminated (step S2). .
[0031]
In step S1, when the target pixel is a black pixel, the edge detection unit 31 checks whether there are white pixels in the surrounding eight pixels (step S3), and in step S3, the white pixels are in the surrounding eight pixels. If not, the edge detection unit 31 determines that the target pixel is a non-edge pixel, outputs “0” to the AND circuit 32, and ends the edge detection process for the target pixel (step S2). .
[0032]
In step S3, when there are white pixels in the surrounding eight pixels, the edge detection circuit 31 determines that the pixel of interest is an edge pixel, and outputs “1” to the AND circuit 32. The edge detection process is terminated (step S4).
[0033]
The AND circuit (edge deletion means) 32 calculates the logical product of the input image data and the inverted output of the edge detection unit 31 and outputs the logical product to the line memory 15 as output image data. Therefore, the AND circuit 32 outputs “0” output image data when the input image data, that is, the target image data is the edge of the black region of the image, and “1” when the input image data is the image data of the black region other than the edge. Is output. The AND circuit 32 outputs “0” output image data to the line memory 15 when the input image data, that is, the target image data is white image data.
[0034]
Therefore, the image processing circuit 30 checks whether each pixel of the input image data sequentially input from the line memory 15 is an edge pixel in the black area of the image, and when it is an edge pixel, “0” indicating a white pixel. ”,“ 1 ”indicating a black pixel when the pixel is a black region other than the edge pixel, and“ 0 ”indicating a white pixel when the pixel is a white region, respectively. The edge pixel of the black area of the data image is discriminated, and the image data in a state where the edge is cut by one pixel is output to the line memory 15 as output image data.
[0035]
Then, the facsimile apparatus 10 transfers the output image data from the line memory 15 to the recording processing unit 14, and the recording scanning unit 13 records and outputs it as a toner image on recording paper.
[0036]
As a result, the facsimile machine 10 has a character image in which the edge of each character image is cut by one dot with respect to input image data (received image data or image data read by the reading scanning unit 11) as shown in FIG. As shown in FIG. 6, the recording scanning unit 13 can record and output the toner image as a clear and readable toner image.
[0037]
Therefore, as compared with the conventional economy mode recording in which the image thinning process shown in FIG. 48 is performed, it is possible to improve character readability and image quality, and to reduce toner consumption.
[0038]
7 to 47,In the facsimile apparatus 10 having the basic configuration described above,The edge shaving amount is determined according to the instruction, and the connectivity of the black area of the image data is determined, and the edge shaving amount is controlled based on the determination result.It is a figure which shows embodiment which added the means to enable it.
[0039]
FIG. 7 is a circuit block diagram of a principal part of the facsimile apparatus 40 of the present embodiment. Although not shown, the facsimile apparatus 40 is the above-described facsimile apparatus 10.(Figure 1 reference)In the same manner, the reading scanning unit 11, the reading processing unit 12, the recording scanning unit 13, the recording processing unit 14, the line memory 15, the line memory control unit 16, the information compression / decompression unit 17, the modem 18, the communication control unit 19, and the network A control unit 20, a DMA controller 21, a ROM 22, an MPU 23, a RAM 24, an interface 25, a mechanism control unit 26, an interface 27, a panel unit 28, and the like are provided. The above units are connected by a bus 29 including a data bus and an address bus. ing.
[0040]
The facsimile apparatus 40 forms an image processing circuit 41 in the MPU 23 in software or hardware. The image processing circuit 41 includes an edge detection unit 42, a connectivity determination unit, as shown in FIG.43And two AND circuits 44 and 45. Edge cutting amount instruction data is input from the edge cutting amount instruction unit 46 to the edge detection unit 42, and the edge cutting amount instruction unit (edge cutting amount instruction means) 46 is provided on the panel unit 28 of the facsimile apparatus 40. . From the edge cutting amount instruction unit 46, input image dataInThe operator of the facsimile apparatus 40 is instructed to input the amount of cutting of the edge portion of the black area, for example, whether to cut 1 dot of the edge portion, 2 dots, or 3 dots. The operation content of the instruction unit 46 is monitored, and the edge cutting amount as the input instruction content is taken into the edge detection unit 42.
[0041]
Connectivity determination unit of the image processing circuit 4143The edge detection unit 44 and the AND circuit 45 receive image data (input image data) from the line memory 15, and the input image dataFacsimile device 10 (Fig. 1 See)Similarly to the above, binary image data in which the black pixel is “1” and the white pixel is “0”.
[0042]
The AND circuit (edge deletion means) 45 is supplied with the input image data and the output of the AND circuit 44 is inverted. The AND circuit 45 receives the logic of the input image data and the inverted input of the AND circuit 44. The product is taken and output to the line memory 15 as output image data.
[0043]
The AND circuit 44 (deletion control means) receives the output of the edge detection unit 42 and the connectivity determination unit.43And the AND circuit 44 takes these logical products and outputs them to the AND circuit 45.
[0044]
Connectivity determination unit (connectivity determination means)43Determines the connectivity of characters and lines in order to prevent the characters and lines from separating or disappearing when the edges detected by the edge detector 42 are deleted. Specifically, connectivity determination unit43Whether the target pixel of the input image data is these diagonal lines in order to maintain diagonal lines, maintain pixel connection points, maintain 2 dot vertical lines, maintain objectivity, maintain 2 dot horizontal lines, etc. It is determined whether it is a 1-pixel connection point, a 2-dot vertical line, a line that requires objectivity, a 2-dot horizontal line, etc. If it is determined that it is a connection point that interferes with maintenance, maintenance of 1 pixel connection point, maintenance of 2 dot vertical line, maintenance of objectivity, maintenance of 2 dot horizontal line, etc., “1” indicating that it is a connection point When the determination output is output to the AND circuit 44, and it is determined that it is not a connection point, a determination output of “0” indicating that it is a non-connection point is output to the AND circuit 44.
[0045]
That is, connectivity determination unit43Uses a 3 × 3, 4 × 5, or 5 × 4 matrix to determine connectivity between the pixel of interest and its surrounding pixels. For example, connectivity determination unit43, As shown in FIGS. 8A, 8B, 8C, and 8D, the pixel of interest at the center of the 3 × 3 matrix is a black pixel as indicated by a black circle ●, and its diagonal direction When one of the pixels located at is a black pixel, if the condition is that one or more of the pixels in the hatched range is a black pixel (hereinafter referred to as condition 1), it is determined to be a diagonal line. Therefore, in order to prevent the diagonal connection from being disconnected, it is determined that the target pixel is a connection point. Connectivity determination unit439 (a) and 9 (b), the center pixel of interest is a black pixel (indicated by ●), and the left and right or upper and lower pixels of the pixel of interest are white pixels (indicated by circles). When it is a condition that one or more of the upper and lower 6 pixels or the left and right 6 pixels indicated by hatching ○ are black pixels (hereinafter referred to as condition 2), In order to prevent the connection between the main scanning direction and the sub-scanning direction from being interrupted, it is determined that the target pixel is a connection point. Furthermore, connectivity determination unit4310 (a) and 10 (b), the pixel of interest at the center is a black pixel (indicated by ●), and the two pixels in the left diagonal direction or right diagonal direction of the pixel of interest are white pixels ( When the condition is such that one or more of the remaining three pixels at the top and bottom of the hatched area indicated by hatching are black pixels (hereinafter referred to as Condition 3), the area is surrounded by white pixels. It is determined that the pixel is a diagonal line, and the pixel of interest is determined to be a connection point so that the connection between the white pixels in the diagonal direction is not interrupted. However, if the determination of FIG. 10 is performed as it is, the diagonal line as shown in FIG. 11 cannot be determined as a connection point and cannot be deleted.43If the connection point determination is excluded under the conditions as shown in FIGS. 12A and 12B (hereinafter referred to as condition 4), the connectivity is maintained as shown in FIG. Edge portions can be deleted. Therefore, connectivity determination unit43In such a case as shown in FIG. 12, it is excluded from connection point determination and is not determined as a connection point. Connectivity determination unit43As shown in FIG. 14, when the pixel of interest is a black pixel and only one pixel is continuous in the horizontal direction in the pixel of interest of this black pixel (hereinafter referred to as condition 5). Is determined to be a connection point in order to prevent the vertical line edge of 2 dots width from being deleted and erased.
[0046]
And connectivity determination unit43For example, when the connectivity determination is performed on the input image as shown in FIG. 15 according to the above conditions 1 to 4 and the edge is deleted, an output image as shown in FIG. 16 is obtained. On the other hand, connectivity determination unit43However, if the above condition 5 is added to the input image as shown in FIG. 15 and the connectivity determination is performed to delete the edge, the way of thinning is different on the left and right, and the output image as shown in FIG. And left and rightSymmetrySexuality is impaired.
[0047]
Therefore, connectivity determination unit43Is determined as a connection point under the conditions shown in FIGS. 19A to 19F (hereinafter referred to as condition 6) using a 4 × 5 matrix as shown in FIG. Avoid deleting pixels. In FIG. 19, the black pixel (indicated by ●) at the position (2, 2) is the target pixel, the pixel indicated by ○ is a white pixel, the pixel indicated by hatching ○ is a pixel satisfying the above condition 1, and ◇ Is a pixel that may be either a white pixel or a black pixel. Such a condition 6 is added to the input image data shown in FIG.43When the connection point is determined and the edge of the input image data is deleted, symmetrical output image data as shown in FIG. 20 can be obtained.
[0048]
Connectivity determination unit43As shown in FIG. 21, in the case where the target pixel is a black pixel and only one pixel is continuous in the vertical direction to the target pixel of the black pixel (hereinafter referred to as condition 7). Is determined to be a connection point in order to prevent the edge of the horizontal line having a width of 2 dots from being deleted and disappearing.
[0049]
And connectivity determination unit43For example, when the connectivity determination is performed on the input image as shown in FIG. 22 according to the above conditions 1 to 6 and the edge is deleted, an output image as shown in FIG. 23 is obtained. On the other hand, connectivity determination unit43However, if the above condition 7 is added to the input image as shown in FIG. 22 and the connectivity determination is performed to delete the edge, the way of thinning up and down is different, resulting in an output image as shown in FIG. Up and downSymmetrySexuality is impaired.
[0050]
Therefore, connectivity determination unit43Is determined as a connection point under the conditions shown in FIGS. 26A to 26F (hereinafter referred to as condition 8) using a 5 × 4 matrix as shown in FIG. Avoid deleting pixels. In FIG. 26, the black pixel (indicated by ●) at the position (2, 3) is the pixel of interest, the pixel indicated by ○ is a white pixel, the pixel indicated by hatching ○ is a pixel satisfying the above condition 1, and ◇ Is a pixel that may be either a white pixel or a black pixel. Such a condition 8 is added to the input image data shown in FIG.43If the connection point is determined and the edge of the input image data is deleted, symmetrical output image data as shown in FIG. 27 can be obtained.
[0051]
In addition, when only one side is left for the input image data composed of diagonal lines with a width of two pixels as shown in FIG. 28, depending on the direction of the diagonal lines, as shown in FIG. The place where it does not become thin occurs, and the symmetry of right and left is lost. Therefore, connectivity determination unit43As shown in FIG. 30, even if there is a target pixel satisfying the above condition 5 (a pixel indicated by a hatched circle in FIG. 28), a black pixel is adjacent to the target pixel and a pixel above it. In the condition (hereinafter, referred to as condition 9), the edge is determined, the connection point is not determined, and the deletionTargetAnd A connectivity determination unit for input image data as shown in FIG.43However, if this condition 9 is added to determine connectivity and edge deletion is performed, left and right symmetrical output image data can be obtained as shown in FIG.
[0052]
Further, when the connection point is determined by the above conditions 1 to 9 and the edge is deleted for the input image data as shown in FIG. 32, the connection point is deleted as shown in FIG. May be separated. Therefore, connectivity determination unit43As shown in FIGS. 34 (a) to (h), under the condition that the black pixel is adjacent to the target pixel in an L shape (regardless of the direction of the L shape) (hereinafter referred to as condition 10). Is determined to be a connection point, and the edge of the target pixel is not deleted. In FIG. 34, the black pixel indicated by ● in the center of the 3 × 3 matrix is the target pixel, the pixel indicated by ● is a black pixel, the pixel indicated by ○ is a white pixel, and the pixel indicated by ◇ is a white pixel and a black pixel. It may be any pixel. Then, a connectivity determination unit for input image data as shown in FIG.43If the condition is added and the connectivity is determined and the edge that satisfies the condition 10 is not deleted, the connection point is maintained and the line is prevented from being separated as shown in FIG. be able to.
[0053]
Also, a connectivity determination unit for input image data in which hollow squares as shown in FIG. 36 are connected.43However, when the connection point is determined according to the above conditions 1 to 10 and the edge is deleted, as shown in FIG. 37, the hollow square connection portion is deleted and the connectivity is lost. Therefore, connectivity determination unit43Is determined to be a connection point under the conditions shown in FIGS. 38A to 38H (hereinafter referred to as condition 11).TargetAnd not. That is, with respect to the target pixel which is the central black pixel, black pixels are adjacent to each other in the vertical and horizontal directions, and three black pixels arranged around the target pixel areOrthogonalA black pixel is present adjacent to the target pixel in the direction in which the black pixel is adjacent, and a black pixel is present adjacent to the black pixel at the end of the three black pixels opposite to the black pixel adjacent to the target pixel. When such a condition 11 exists, the connectivity determination unit43Determines that the pixel of interest is a connection point and deletes itTargetExclude from In FIG. 38, the pixel indicated by ● is a black pixel, the pixel indicated by ○ is a white pixel, and the pixel indicated by ◇ is a pixel that may be either a white pixel or a black pixel. Therefore, a connectivity determination unit for input image data as shown in FIG.43However, when the condition 11 is satisfied, it is determined that the point is a connection point and is excluded from the deletion target. As shown in FIG. 39, edge deletion can be performed while maintaining the connectivity of the input image data.
[0054]
The edge detection unit (edge detection means) 42 uses, for example, a 3 × 3 matrix composed of pixels C1 to C9 as shown in FIG. It is determined whether the left edge, the lower edge, the right edge, or the upper edge of the black area of the image of the input image data, and the edge is determined according to the edge cutting amount instruction from the edge cutting amount instruction unit 46. Perform detection.
[0055]
For example, when one-dot cutting is instructed from the edge cutting amount instruction unit 46, the edge detection unit 42 indicates that either the left pixel C4 or the lower pixel C8 of the target pixel C5 is white as shown in FIG. Whether it is a left edge or a lower edge is detected depending on whether it is a pixel. In FIG. 41, ● is a black pixel, ○ is a white pixel, and * is a pixel that may be either a white pixel or a black pixel. That is, the edge detection unit 42 first uses the 3 × 3 matrix shown in FIG. 40 and uses the 3 × 3 matrix shown in FIG. 40, as shown in FIG. It is checked whether C5 is a black pixel (step P1). If the target pixel C5 is not a black pixel, it is determined that it is not an edge but a pixel outside the deletion symmetry, and “0” indicating that it is a non-edge is ANDed. It outputs to the circuit 44 (step P2). In step P1, when the target pixel C5 is a black pixel, the edge detection unit 42 checks whether the left pixel C4 or the lower pixel C8 adjacent to the target pixel C5 is a white pixel (step P3), and the left pixel C4 and When both of the lower pixels C8 are not white pixels, it is determined that the pixel is not a left edge or a lower edge and is a pixel outside the deletion symmetry, and “0” indicating non-edge is output to the AND circuit 44 ( Step P2). In step P3, when either the left pixel C4 or the lower pixel C8 is a white pixel, the edge detection unit 42 determines that the target pixel C5 is the left edge or the lower edge and is the edge to be deleted. Then, “1” indicating an edge is output to the AND circuit 44 (step P4).
[0056]
Further, when the edge detection unit 42 is instructed to cut two dots by the edge cutting amount instruction unit 46, the edge detection unit 42, as shown in FIG. 43, the pixel C2 above the target pixel C5, the left pixel Whether any of the upper edge, the left edge, the right edge, and the lower edge is detected depending on whether any of C4, right pixel C6, or lower pixel C8 is a white pixel. In FIG. 43, ● is a black pixel, ○ is a white pixel, and * is a pixel that may be either a white pixel or a black pixel. That is, the edge detection unit 42 first uses the 3 × 3 matrix shown in FIG. 40 and uses the 3 × 3 matrix shown in FIG. 40, as shown in FIG. It is checked whether C5 is a black pixel (step P11). If the target pixel C5 is not a black pixel, it is determined that it is not an edge but a pixel outside the deletion symmetry, and “0” indicating non-edge is ANDed. It outputs to the circuit 44 (step P12). In step P11, when the target pixel C5 is a black pixel, the edge detection unit 42 determines whether any of the upper pixel C2, the left pixel C4, the right image C6, or the lower pixel C8 adjacent to the target pixel C5 is a white pixel. Check if there is any (Step P13), and if any of the upper pixel C2, the left pixel C4, the right image C6 and the lower pixel C8 is not a white pixel, it is not an upper edge, a left edge, a right edge or a lower edge, and is deleted It is determined that the pixel is out of symmetry, and “0” indicating non-edge is output to the AND circuit 44 (step P12). In step P13, when any of the upper pixel C2, the left pixel C4, the right image C6, or the lower pixel C8 is a white pixel, the edge detection unit 42 determines that the target pixel C5 is an upper edge, a left edge, or a right edge. Or the lower edge, it is determined that the edge is a deletion target edge, and “1” indicating the edge is output to the AND circuit 44 (step P14).
[0057]
When the edge deletion amount instruction unit 46 instructs to delete three or more dots, the edge detection unit 42 first performs one of the above-described one-dot cutting edge detection processing and two-dot cutting edge detection processing. Then, the edge performs the deletion process based on the edge detection process, and the image data from which the edge has been deleted is again either one-dot-cut edge detection process or two-dot-cut edge detection process. It is possible to cope with this by circulating these.
[0058]
Returning to FIG. 7 again, as described above, the edge detection output of the edge detection unit 42 is input to the AND circuit 44, and the connectivity determination result output is inverted from the connectivity determination unit 43. The AND circuit 44 takes these logical products and outputs them to the AND circuit 45. That is, the AND circuit 44 outputs “1” indicating that the edge detection unit 42 is an edge, and “1” when the connectivity determination unit 43 outputs “0” indicating that it is a non-connection point. Is output to the AND circuit 45, and “0” is output to the AND circuit 45 at other times.
[0059]
As described above, the AND output of the AND circuit 44 is inverted and input image data is input to the AND circuit 45, and the AND circuit 45 calculates the logical product of these inputs as output image data. Output to the line memory 15. That is, when the AND circuit 45 determines that the input image data is a black pixel, the edge detection unit 42 is an edge pixel, and the connectivity determination unit 43 determines that the input pixel is a non-connection point, Output image data that has been subjected to edge deletion is output to the line memory 15 as white pixels. Otherwise, output image data that is the same as the input image data is output to the line memory 15.
[0060]
When the output image data is accumulated in the line memory 15 in this way, the facsimile apparatus 40Facsimile device 10 (Fig. 1 See)Similarly, the image data is transferred from the line memory 15 to the recording processing unit 14, and the toner image is recorded on the recording paper by the recording scanning unit 13.
[0061]
Therefore, according to the present embodiment, for the input image data as shown in FIG. 5, when the edge cutting amount instruction unit 46 instructs, for example, 2-dot cutting, the edge detection unit 42. 44 performs edge detection processing as shown in FIG. 44, and as shown in FIG. 45, the connectivity determination unit 43 determines the connectivity, while maintaining the connectivity appropriately, the top, bottom, left, and right are 1 dot. It is possible to record and output an output image with good character readability and good image quality while deleting and reducing toner. In this case, the black pixel is 17733 pixels in the input image, but the black pixel is reduced to 10229 pixels in the output image, and the toner consumption is reduced.
[0062]
Further, for example, when the edge cutting amount instruction unit 46 instructs 3-dot cutting for the input image data shown in FIG. 5, the edge detection processing and the edge shown in FIG. As shown in FIG. 46, the deletion processing is performed, and the edge detection processing and edge deletion processing shown in FIG. 42 are performed on the edge-deleted image data, and the connectivity determination unit 43 performs connectivity determination simultaneously. It is possible to record and output an output image with good character readability and good image quality while eliminating three dots to reduce toner. In this case, in the input image, the black pixels were 17733 pixels, but in the output image, the black pixels were reduced to 7626 pixels, compared to the conventional thinning that was reduced to 8055 pixels. As the number of black pixels is reduced, toner can be further reduced, and as can be seen from FIG. 51, which is an output image that has undergone thinning processing, character readability and image quality are improved. It has improved.
[0063]
Further, for example, in the case where the edge cutting amount instruction unit 46 has instructed 4-dot cutting with respect to the input image data shown in FIG. 5, the edge detection processing and edge shown in FIG. 47, the edge detection process and the edge deletion process shown in FIG. 44 are performed again on the edge-deleted image data, and the connectivity determination by the connectivity determination unit 43 is performed simultaneously. As described above, it is possible to record and output an output image with good readability and good image quality while eliminating toner by deleting four dots. In this case, in the input image, the black pixels were 17733 pixels, but in the output image, the black pixels were reduced to 6015 pixels, compared to the conventional thinning that was reduced to 8055 pixels. The number of black pixels is greatly reduced, toner can be further reduced, and as can be seen from FIG. 51, which is an output image obtained by performing a conventional thinning process, character readability and image Quality has improved.
[0064]
The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.
[0065]
For example, in each of the above embodiments, the present invention is applied when recording is performed with an electrophotographic recording apparatus that uses toner as a recording material. However, the recording material is not limited to toner, and for example, an ink ejection type The same can be applied to ink or the like of a recording apparatus.
[0066]
【The invention's effect】
According to the image processing apparatus of the first aspect of the invention, since the edge of the black area of the image is detected and the edge of the black area is deleted by a predetermined amount, the conventional black area thinning process is not performed. By reducing the size of characters, it is possible to maintain good readability and good image quality during copying, and to reduce consumption of recording materials.AndEdge of black area of image, edgeDeleted amountSince only the amount corresponding to the instruction from the instruction means is deleted, the balance between the character readability and the image quality and the consumption of the recording material can be appropriately selected.
[0067]
Claim2According to the image processing apparatus of the invention described above, since the connectivity of the black area of the image is detected and the amount of deletion of the edge of the black area of the image is controlled, the connected portion of the black area of the image is the black area of the image. It is possible to prevent cutting or smearing by deleting the edges of the image, further improving the character readability and image quality, and reducing the consumption of the recording material.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a facsimile apparatus to which the present invention is applied.
FIG. 2 is a circuit diagram of an image processing circuit formed in the MPU of FIG.
FIG. 3 is a diagram illustrating an example of a matrix used in the edge detection unit in FIG. 2;
FIG. 4 is a flowchart showing edge detection processing in the edge detection unit of FIG. 2;
FIG. 5 is a diagram showing an example of an input image whose edge is deleted in an econo mode by the facsimile apparatus of FIG. 1;
6 is a diagram showing an example of an output image obtained by deleting two dots from the edge of the input image in FIG. 5 in the econo mode by the facsimile apparatus in FIG. 1;
FIG. 7 is a main circuit of a facsimile apparatus to which the present invention is applied.Block showingFigure.
8 is a matrix diagram showing Condition 1 for determining the connectivity of diagonal lines by the connectivity determination unit of FIG. 7;
9 is a matrix diagram showing Condition 2 for determining connectivity in the sub-scanning direction (a) and main scanning direction (b) by the connectivity determining unit in FIG. 7;
FIG. 10 is a matrix diagram showing condition 3 for determining connectivity of diagonal lines (a) and (b) sandwiched between white pixels in an oblique direction.
FIG. 11 is a diagram showing an example of an input image made up of diagonal lines.
12 is a matrix diagram showing condition 4 for determining the connectivity of the input image in FIG. 11;
13 is a diagram showing an example of an output image obtained by deleting the edge by determining the connectivity of the input image of FIG. 11 under the conditions of FIG. 12;
FIG. 14 is a matrix diagram showing Condition 5 for preventing a 2-dot-width straight line from being deleted;
FIG. 15 is a diagram showing an example of an input image made up of diagonal lines.
FIG. 16 is a diagram showing an example of an output image obtained by deleting the edge by determining the connectivity of the input image of FIG. 15 under conditions 1 to 4;
FIG. 17 is a diagram showing an example of an output image obtained by deleting the edge of the input image shown in FIG.
18 is a diagram illustrating an example of a 4 × 5 matrix used in the connectivity determination unit in FIG. 7;
FIG. 19 is a matrix diagram showing condition 6 for ensuring left-right symmetry in connectivity determination when condition 5 is added.
20 is a view showing an example of an output image obtained by deleting the edge of the input image of FIG. 15 by adding the condition 6 of FIG. 19 and determining connectivity.
FIG. 21 is a matrix diagram showing condition 7 for preventing a 2-dot straight line from being erased by edge deletion in the main scanning direction;
FIG. 22 is a diagram showing an example of an input image made up of diagonal lines.
FIG. 23 is a diagram showing an example of an output image obtained by deleting the edge after determining the connectivity of the input image of FIG. 22 under conditions 1 to 6;
24 is a diagram showing an example of an output image obtained by deleting the edge by adding the condition 7 to the input image shown in FIG. 22 and determining connectivity. FIG.
25 is a diagram showing an example of a 5 × 4 matrix used in the connectivity determination unit in FIG.
FIG. 26 is a matrix diagram showing condition 8 for ensuring left-right symmetry in connectivity determination when condition 7 is added.
27 is a diagram showing an example of an output image obtained by deleting the edge of the input image shown in FIG. 22 by adding the condition 8 shown in FIG. 26 and determining connectivity.
FIG. 28 is a diagram showing an example of an input image made up of diagonal lines.
29 is a diagram showing an example of an output image obtained by deleting the edge by determining the connectivity of the input image of FIG. 22 under conditions 1 to 8;
FIG. 30 is a matrix diagram showing a condition 9 for ensuring symmetry of the thickness of the diagonal line in the connectivity determination when the conditions 1 to 8 are added.
31 is a diagram showing an example of an output image obtained by deleting the edge by adding the condition 9 of FIG. 30 and determining the connectivity of the input image of FIG. 28;
FIG. 32 is a diagram illustrating an example of an input image in which individual images are in contact with each other.
FIG. 33 is a diagram showing an example of an output image obtained by deleting the edge by determining the connectivity of the input image of FIG. 32 under conditions 1 to 9;
FIG. 34 is a matrix diagram showing a condition 10 for ensuring continuity between images in contact with each other.
FIG. 35 is a diagram showing an example of an output image obtained by deleting the edge by adding the condition 10 to the input image shown in FIG. 32 and determining connectivity.
FIG. 36 is a diagram illustrating an example of an input image in which a plurality of images are in contact with each other in an oblique direction and are continuous.
FIG. 37 is a diagram showing an example of an output image obtained by deleting the edge after determining the connectivity of the input image in FIG. 36 under conditions 1 to 10;
FIG. 38 is a matrix diagram showing a condition 11 for ensuring the continuity of an input image in which a plurality of images contact in an oblique direction and are continuous.
FIG. 39 is a diagram showing an example of an output image obtained by deleting the edge by adding the condition 11 to the input image of FIG. 36 and determining connectivity.
40 is a diagram showing an example of a matrix used in the edge detection unit of FIG.
FIG. 41 is a matrix diagram showing edge detection conditions for a target pixel and a white pixel when performing 1-dot cutting.
42 is a flowchart showing edge detection processing when performing one-dot cutting by the edge detection unit in FIG. 7;
FIG. 43 is a matrix diagram showing edge detection conditions for a target pixel and a white pixel when performing two-dot cutting.
44 is a flowchart showing edge detection processing when performing 2-dot cutting by the edge detection unit of FIG. 7;
45 is a view showing an example of an output image obtained by deleting two dots from the edge of the input image in FIG. 5 in the econo mode by the facsimile apparatus in FIG. 7;
46 is a view showing an example of an output image obtained by deleting three dots from the edge of the input image in FIG. 5 in the econo mode by the facsimile apparatus in FIG. 7;
47 is a diagram showing an example of an output image obtained by deleting four dots from the edge of the input image in FIG. 5 in the econo mode by the facsimile apparatus in FIG. 7;
FIG. 48 is a diagram showing an example of an image processing circuit that performs toner reduction by a conventional thinning process.
FIG. 49 is a diagram showing a bit pattern used for thinning processing in the image processing circuit of FIG. 48;
50 is a diagram showing an example of an input image input to the conventional image processing circuit of FIG. 48. FIG.
51 is a diagram showing an example of an output image obtained by thinning out the input image of FIG. 50 by the conventional image processing circuit of FIG. 48;
[Explanation of symbols]
10 Facsimile machine
11 Scanning section
12 Reading processing unit
13 Recording scanning unit
14 Recording processing section
15 line memory
16 line memory controller
17 Information compression / decompression unit
18 Modem
19 Communication control unit
20 Network control unit
21 DMA controller
22 ROM
23 MPU
24 RAM
25 interface
26 Mechanism control unit
27 Interface
28 Panel
29 Bus
30 Image processing circuit
31 Edge detector
32 AND circuit
40 facsimile machine

Claims (2)

It is possible to operate in the imaging material saving mode in which a part of the black pixels of the original image data to be processed is deleted and an image is recorded on the recording paper using the imaging material based on the deleted image data. A deletion amount instruction means for instructing a deletion amount of a black pixel, and a deletion target in the original image data by pixel matrix processing under a condition corresponding to the deletion amount instructed by the deletion amount instruction means. An image processing apparatus comprising: edge detection means for performing processing for detecting an edge of the black pixel area, and means for deleting the edge of the black pixel area detected by the edge detection means from the original image data. 2. The connectivity determination means according to claim 1, wherein connectivity determination means for determining presence / absence of connectivity with surrounding black pixels of black pixels of original image data to be processed by pixel matrix processing, and the connectivity determination An image processing apparatus, further comprising: a deletion control unit that operates the edge deletion unit on condition that the determination result of the unit is no connectivity.

Images