JP3143149B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for reading a document image by photoelectric conversion means, performing image processing on the read image data, and outputting binary data.

[0002]

2. Description of the Related Art In a conventional copying apparatus, plate making apparatus, facsimile machine or the like, an image of a document is read by a reading means such as a CCD sensor and multi-valued image data of the read document, that is, the density of the document is simply binary. By using an image processing device that performs binarization or binarization using a halftone reproduction method such as a known dither process or an error diffusion method, the image of the document is output sharply.

The general operation of a stencil printing apparatus using the above-described image processing apparatus will be described below with reference to FIG. 7, and FIG. 8 shows the basic circuit configuration of an image processing system of the stencil printing apparatus. FIG.

As shown in FIG. 7, this type of stencil printing apparatus includes an image input section 1 having a CCD sensor 7 for picking up an image of an original X, and a document X picked up by the CCD sensor 7 of the image input section 1. Image processing apparatus 2 for processing the image signal of the image forming apparatus, and a heat-sensitive stencil sheet Z (hereinafter, referred to as a master) composed of a thermoplastic synthetic resin film and an ink-permeable support based on the image data processed by the image processing apparatus 2. Plate making means 3 comprising a thermal head 3a or the like for forming a perforated image, a drum 4 for supplying ink to the outer peripheral surface from the inside around which the master Z is wound, and a drum 4 and a press. The printing paper P is sandwiched and supplied between the rollers 5, and at the same time, the ink passing through the perforated image portion formed on the master Z is transferred to the printing paper P, and the printing paper P is transported. It is schematically configured from the printing and conveying section 6.

As shown in FIG. 8, the image input section 1 has a CCD sensor 7 and an A / D converter for converting an analog video signal into an 8-bit multi-valued video signal. An image processing device 2 is connected to a stage subsequent to the image input unit 1 as well as a converter 8.

The image processing apparatus 2 inverts the image data input from the image input section 1 for each bit by an inverter 9 so as to be suitable for image recording of a stencil printing apparatus. , So that the read signal from the darkest part becomes 255.

Reference numeral 10 denotes a conventionally known shading correction circuit, which performs shading correction for normalizing the white level of the read signal to 0, and converts the normalized video signal into a density conversion adjusted to the output characteristics of the stencil printing apparatus. Table 1
After being converted in step 1, the data is input to a photographic processing circuit 12 and a simple binarization circuit 13, which are halftone processing circuits, and output as video data such as a photographic output such as a halftone dot or a silver halide photograph and a character output. The signal is input to the A input terminal and the B input terminal of the selector 14.

Each of the video data input to the selector 14 selects either a photographic image or a character image according to a signal “SEL” from a CPU (not shown) in the selector 14 and inputs the selected image to the mask processing circuit 15. .

The mask processing circuit 15 limits the printing surface in accordance with the size of the sheet to be transferred. The masked video signal is converted by the TPH address conversion circuit 16 into a perforated image signal suitable for the driving conditions of the thermal head. After the conversion, the perforated image is formed on the thermal film of the master Z by the thermal head 3a of the plate making means 3.

A stencil printing machine, in which a master Z having a perforated image formed on a heat-sensitive film, is wound around a drum 4 and transfers ink to a printing paper P via a press roller 5 to obtain an output image, as described above. Was common.

[0011]

However, when the master Z on which the perforated image is formed as described above is printed by using the above-described conventional stencil printing apparatus, especially when the image of the original X has a solid portion. A so-called "show-through" in which the amount of ink in this portion transferred to the printing paper P becomes larger than that in other image portions, and the ink transfers to the back surface of the printing paper P to be printed and stacked next. There is a problem that the above phenomenon becomes remarkable.

In order to control the print density, that is, the amount of transferred ink, in order to eliminate the "show-through" phenomenon, the printing speed must be controlled or the pressure between the drum 4 and the press roller 5 must be controlled. Therefore, there is a problem that a complicated and large-scale mechanism is required, which causes an increase in cost and also requires adjustment and the like, which is troublesome.

Under such circumstances, the amount of ink transferred to the printing paper can be easily controlled,
An image processing apparatus capable of outputting a clear image has been desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to easily control the amount of ink transfer particularly in a solid portion of an output image, and to achieve fine lines and thin lines. An object of the present invention is to provide an image processing apparatus capable of clearly outputting fine characters and the like.

[0015]

In order to achieve the above object, the present invention has a photographic processing circuit and a simple binarizing circuit as described in claim 1,
In an image processing apparatus that processes a document read by a photoelectric conversion unit as an image signal of binarized data for each pixel, a thin line recognition processing unit that detects an image signal having a predetermined pixel width, and an image signal that is detected by the thin line recognition processing unit When the image signal is equal to or larger than a predetermined pixel width, an image signal in which a white signal is forcibly added at a predetermined pixel interval to a continuous black signal image signal corresponding to a continuous high-density portion of a read document. And a thinning processing means.

According to a second aspect of the present invention, in an image processing apparatus for processing a document read by photoelectric conversion means as an image signal of binarized data for each pixel, the document corresponds to a continuous high density portion of the read document. It is characterized in that a thinning-out processing means is provided for converting a continuous black signal image signal into an image signal in which a white signal is forcibly added at a predetermined pixel interval.

[0017]

According to the present invention, when the image signal detected by the fine line recognition processing means is equal to or larger than a predetermined pixel width, a thinning process is performed on a continuous black signal image signal corresponding to a continuous high density portion of a read original. The image signal is obtained by forcibly adding a white signal at predetermined pixel intervals by means.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an image processing apparatus according to the present invention. Since the same members as those shown in FIG. 8 perform the same operation, the same reference numerals are given and the detailed description thereof will be omitted.

In FIG. 1, an image signal of a document X picked up by the CCD sensor 7 of the image input unit 1 is converted from an analog video signal into an 8-bit multi-valued video signal by an A / D converter 8, and image processing is performed. Inverter 9 of device 2
Thus, data inversion is performed for each bit so as to be suitable for image recording of the stencil printing apparatus, and processing is performed so that the read signal from the brightest portion becomes 0 and the read signal from the darkest portion becomes 255.

The shading correction circuit 10 normalizes the white level of the read signal to 0, and the normalized video signal is converted into an 8-bit video signal by the density conversion table 11 so as to match the output characteristics of the stencil printing apparatus. A photographic processing circuit 12 for converting a signal into a halftone process such as a halftone dot or a silver halide photograph, and a simple binarization circuit 1
3 and the thinning processing circuit 20 according to the gist of the present invention.

The video signal for each pixel input to each of the circuits 12, 13 and 20 is not shown in the figure but is generated by a timing generating circuit in a direction perpendicular to the arrangement direction (main scanning direction) of the light receiving elements of the CCD 7 and the main scanning direction. The direction in which the document relatively moves and scans (sub-scanning direction) is completely synchronized, and the three types of binary signals PH, TX, and G input to the selector 14 are provided.
R is a video signal at the same coordinate position on the document.

Next, referring to FIG.
The operation of 0 will be described. FIG. 2 is a conceptual diagram of the thinning processing circuit 20. The main scanning CNT 103 is synchronized with a video signal, a horizontal synchronization signal HSYNC and a video clock signal CK, and is synchronized with a preset value from a CPU (not shown). The counter value is output via the signal line 105 at a certain cycle, and the output counter value is stored in the ROM
102 is input to the lower address.

The sub-scan CNT 104 has a vertical synchronization signal VSYNC and a horizontal synchronization signal HSYNC.
The counter value is synchronized at a certain cycle by a preset value from a CPU (not shown).
And the output counter value is stored in the ROM 102
Is input to the upper address.

On the other hand, the main scanning CNT is stored in the ROM 102.
The threshold value corresponding to the video signal is written in hexadecimal notation by the output of 103 and the sub-scan CNT 104.

The output from the ROM 102 is input to the B input terminal of the two A and B input terminals of the comparator 101, and an 8-bit video signal is input to the other A input terminal of the comparator 101. , The video signal and the threshold value from the ROM 102 are compared in the comparator 101.

In this case, when the video signal input from the A input terminal is larger than the threshold value input from the B input terminal (A> B), “1” representing a black signal is output from the comparator 101. You.

Conversely, when the video signal input from the A input terminal is smaller than the threshold value input from the B input terminal (A <B), “0” representing a white signal is output from the comparator 101. As a result, the comparator 101
Outputs a binary signal.

The outline of the thinning processing operation has been described above with reference to the circuit diagram of FIG. 2. Next, the relationship with the output image will be specifically described with reference to FIG.

FIG. 3A is a conceptual diagram of the thinning process.
As shown in the figure, 4 × 4 in the main scanning direction and the sub-scanning direction.
In this embodiment, a matrix window corresponds to one pixel.

Further, the circuit has a circuit configuration that can set a threshold value corresponding to each matrix. This circuit configuration is set in the table of the ROM 102 as described above. The threshold value is set as 80H, FFH or the like represented by a hexadecimal number as shown in FIG.

Here, in both the main scanning direction and the sub-scanning direction, the threshold value in the main scanning direction is periodically changed from A to B to C to D to A... When the period ends, next, the line A is periodically changed from A to B.

In this case, the input terminal B of the comparator 101 has a hexadecimal number of 8 as shown in FIG.
0, 80, FF, and FF are input.

Assuming that a video signal having a density of, for example, C0 in hexadecimal is continuously input as a video signal, a white signal is forcibly added for every two pixels according to the present embodiment. The black and white patterns shown in FIG. 3B are output.

This means that, for example, when the thinning process according to the present embodiment is performed on the original 201 as shown in FIG. As shown in the drawing 201a, the master Z is perforated in a grid pattern.

Therefore, since the solid portion is thinned out every two pixels, the ink penetrates through the perforated portion and is transferred to the printing paper P, and as described above, the dispersion of the water content of the ink is fast, and Is also limited, and a high-quality printed matter with little show-through can be obtained.

However, in this case, the thin line as shown in the II portion of FIG. 3 may lose the image information depending on the period of the matrix, so that only the output image as shown in 201b may be obtained, which may cause inconvenience. is there.

Next, means for eliminating the inconvenience that occurs in the case of such a thin line will be described with reference to FIGS. In FIG. 1, the signal binarized by the simple binarization circuit 13 is input to the selector 14 and also to the thin line recognition processing circuit 21 as a signal TVD.

FIG. 5 is a block diagram of the fine line recognition processing circuit 21. Reference numerals 301, 302, 303, and 304 denote memories for one line, each of which is one line for the binary signal TVD.
Signals D1, D delayed by two, three, and four lines
2, D3 and D4 are output.

Reference numerals 305 to 316 denote latches each corresponding to one pixel. For example, reference numerals 309 to 312 hold signals obtained by delaying the D1 signal by one pixel, two pixels, three pixels, and four pixels, respectively. L5, L6 in 312
The L7 and L8 signals are image signals of four consecutive pixels.

Accordingly, the memory output signals D1, D2, D3, D4 and DO of the four lines described above, the signal D2 and the signals L5 to L8 in the latches of 309 to 312 are used in the main scanning direction and the sub-scanning direction. Figure 6 of × 5
The cross pattern 401 shown in FIG.

Therefore, the patterns A, B, and C in the main scanning direction and the patterns D, E, and
F is detected independently of each other. In the drawing, the symbol ● indicates a black binary signal, and the symbol ○ indicates a white binary signal.

Next, the thin line detection direction will be described by taking pattern A as an example. Consecutive three pixels, that is, L5, L6, L
When the seven signals L5 are white, L6 is black, and L7 is white, the arithmetic circuit 317 forcibly outputs the black signal "1" on the output signal LINE.

At this time, it is determined that the line is a thin line of one dot continuous in the sub-scanning direction, and the "1" signal output on LINE is output by the OR gate 22 shown in FIG.
Regardless of the output from 0, "1" which is a black signal is always input to the selector 14. Similarly, fine lines continuous in the main scanning direction are detected by pattern D. Further, pattern B.
In C, a line signal for two pixels continuous in the sub-scanning direction is detected, and a black signal for two pixels is output. The pattern E. In F, a line signal for two pixels continuous in the main scanning direction is detected, and a black signal for two pixels is output.

As described above, the video signal processed by the thinning processing circuit 20 in the present embodiment and the thin line recognition processing circuit 21 processed by the image processing based on the TVD signal from the simple binarization circuit 13 are used. The video signal is input to the C input terminal of the selector 14 as a video signal GR that has been logically ORed by the OR gate 22.

When the thinning processing mode is selected on a panel of a stencil printing machine (not shown), a GR video signal is sent to the mask processing circuit 15 by a combination of select signals SEL1 and SEL2 from a CPU (not shown). A perforated image is formed on the master Z by the thermal head 3a of the plate making means 3.

Therefore, if the image of the original X has a solid portion of a high density portion and the image processing is performed as it is, an excessive amount of ink is supplied to the output image side, so that the image is printed and stacked next. In the case where show-through occurs in which the ink of the image formed by the previous printing is transferred on the back surface of the printing paper P, the thinning processing circuit 20 forcibly outputs a white signal at a predetermined pixel interval. An image signal obtained by performing a thinning process on the added and continuous black signals can be obtained.

When a thin line or a thin character is read and output instead of the solid portion of the original X, if the thin line recognition processing mode is selected on the panel of the stencil printing machine (not shown) as described above, the fine line recognition processing circuit 21 detects that the pixel width is within the predetermined pixel width. In this case, the OR gate 2
2, the signal from the thin line recognition processing circuit 21 can be preferentially output by the logical sum, and the thinning processing circuit 20 can be output.
Since the white signal forcibly added in the above can be forcibly changed to a black signal, it is possible to output fine lines or fine characters without losing some of the fine lines and fine characters.

[0048]

As described above, according to the present invention,
If the image signal detected by the fine line recognition processing means is equal to or larger than the predetermined pixel width, the thinning processing means sets the predetermined pixel interval between the continuous black signal image signals corresponding to the continuous high density portions of the read document. Therefore, it is possible to easily control the amount of ink transfer particularly in the solid part of the output image, and also to make thin lines and thin characters part of the output image. Can be obtained as a clear output image without dropout.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image processing apparatus according to the present invention.

FIG. 2 is a conceptual diagram of a thinning processing circuit.

FIG. 3 is an explanatory diagram showing a relationship with an output image in a thinning process.

FIG. 4 is an explanatory diagram illustrating an example of a printed material subjected to a thinning process.

FIG. 5 is a block diagram of a thin line recognition processing circuit.

FIG. 6 is a diagram illustrating a thin line recognition pattern in a thin line recognition process.

FIG. 7 is a schematic explanatory view of a stencil printing apparatus.

FIG. 8 is a basic block diagram of an image processing system of the stencil printing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image input part 2 Image processing apparatus 3 Plate making means 12 Photo processing circuit 13 Simple binarization circuit 20 Thinning-out processing circuit 21 Fine line recognition processing circuit 22 OR gate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409

Claims (2)

(57) [Claims] An image processing apparatus having a photo processing circuit, a simple binarizing circuit, and the like, and processing a document read by a photoelectric conversion unit as an image signal of binarized data for each pixel. A thin line recognition processing means for detecting a signal, and when the image signal detected by the fine line recognition processing means is equal to or larger than a predetermined pixel width, the image signal is converted into a continuous black signal image signal corresponding to a continuous high density portion of the read document. On the other hand, an image processing apparatus comprising: a thinning-out processing unit that forcibly adds an white signal with a predetermined pixel interval to an image signal. 2. An image processing apparatus for processing a document read by photoelectric conversion means as an image signal of binarized data for each pixel, wherein a continuous black signal image signal corresponding to a continuous high-density portion of the read document is generated. On the other hand, there is provided an image processing apparatus provided with thinning-out processing means for forcibly generating an image signal to which a white signal is added at a predetermined pixel interval.