JP3143150B2 - 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 including a thermal head 3a for forming a perforated image, a drum 4 for supplying ink to the outer peripheral surface from the inside where the master Z is wound, and the drum 4
And a printing / conveying device for sandwiching and supplying the printing paper P between the press rollers 5, transferring ink passing through the perforated image portion formed on the master Z to the printing paper P, and conveying the printing paper P. And a 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 into a perforated image signal suitable for the driving condition of the thermal head 13a in the TPH address conversion circuit 16. The perforated image is formed on the thermoplastic synthetic resin film of the master Z by the thermal head 3a of the plate making means 3.

The master Z having the perforated image formed on the thermoplastic synthetic resin film is wound around the drum 4 as described above, and the ink is transferred to the printing paper P via the press roller 5 to obtain an output image. Stencil printing machines were 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. The so-called “show-through” phenomenon in which the amount of ink transferred to the printing paper P becomes larger than that of other image portions and the ink is transferred to the back surface of the printing paper P to be printed and stacked next. There was a problem that it became noticeable.

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 circumstances, and has as its object to perform ordinary image processing and to easily control the amount of ink transfer particularly in a solid portion in an output image. It is an object of the present invention to provide an image processing apparatus which can output fine lines and fine characters clearly.

[0015]

In order to achieve the above object, the present invention has a photographic processing circuit, a simple binarizing circuit, and the like. In an image processing device for processing as an image signal of the digitized data, a thin line recognition processing unit that detects an image signal having a predetermined pixel width, and when the image signal detected by the thin line recognition processing unit is equal to or more than a predetermined pixel width, Thinning processing means for forcibly converting a continuous black signal image signal corresponding to a continuous high-density portion of a read original into an image signal in which a white signal is forcibly added at a predetermined pixel interval; And a mode selection means for selecting each image processing mode, such as a simple binarization circuit, a thin line recognition processing means, and a thinning processing means.

[0016]

According to the present invention, by selecting an image processing mode such as a photo processing circuit or a simple binarizing circuit, image processing of a halftone original such as a normal halftone dot or a silver halide photograph, and character image processing are performed. In addition to the above, the image processing mode of the thin line recognition processing unit can be selected to output a clear image of a thin line, a thin character, or the like, and the solid image processing can be performed by selecting the image processing mode of the thinning processing unit. It is also possible to obtain a high quality image output without show-through.

[0017]

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 the original 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.

Further, the white level of the read signal is normalized to 0 by the shading correction circuit 10, 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.

Although not shown, the video signal for each pixel input to each of the circuits 12, 13, and 20 is provided by a timing generation circuit in a direction perpendicular to the arrangement direction (main scanning direction) of the light receiving elements of the CCD 7 in the vertical 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, with reference to FIG.
The operation of 0 will be described. Figure 2 is a conceptual diagram of a thinning-out process circuit 20, a main scanning CNT103 is synchronized by CK is HSYNC and video clock signal is a video signal and a horizontal synchronizing signal is taken, the counter in a cycle with the preset value from the CPU40 The value is output via the signal line 105, and the output counter value is input to the lower address of the ROM 102.

The sub-scan CNT 104 has a vertical synchronization signal VSYNC and a horizontal synchronization signal HSYNC.
The counter value is output via the signal line 106 at a certain period according to the preset value from the CPU 40 , and the output counter value is input to the upper address of the ROM 102.

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), the comparator 101 outputs “0” representing a white signal. 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-out processing. As shown in FIG. 3, a 4 × 4 matrix window is provided in the main scanning direction and the sub-scanning direction, and the unit of the matrix corresponds to one pixel in this embodiment. are doing.

Further, it 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, B of comparator 101
The input terminal 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 every two pixels according to the present embodiment. The black and white patterns shown in FIG. 3B are output.

This is because, for example, when the original 201 shown in FIG. 4 is subjected to the thinning-out processing according to the present embodiment, the solid portion such as the I portion is enlarged when the portion is viewed as an arrow in the drawing. 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 from the perforated portion and is transferred to the printing paper P, and as described above, the water contained in the ink is quickly dispersed and the ink is dispersed. 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 portion II in the figure loses the image information depending on the period of the matrix, so that only the output image as shown in 201b is 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. Binarized signal by simple binarization circuit 13 in FIG. 1 is also input to the fine line recognition processing circuit 21 as a signal TVD is inputted to the selector 14.
FIG. 5 is a block diagram of the fine line recognition processing circuit 21.
1, 302, 303, and 304 are memories for one line.
1 line, 2 lines, 3 lines for the binarized signal TVD
Lines, signals D1, D2, D3, D4 delayed by 4 lines
Is 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 above-mentioned four lines and the signals L5 to L8 in the latches of the signals D2 and 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 the 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, the 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 this 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 by the mode selecting means 30 provided on the panel of the stencil printing apparatus, a select signal SEL from the CPU 40 is issued.
The GR video signal is sent to the mask processing circuit 15 by a combination of 1 and SEL2, and is formed as a perforated image on the master Z by the thermal head 3a of the plate making means 3.

Therefore, if the image of the document 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, and the next image is printed and stacked. 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.

In the case of reading and outputting thin lines and thin characters instead of the solid portion of the original X, when the thin line recognition processing mode is selected by the mode selection means 30 provided on the panel of the stencil printing apparatus, the CPU 40 Since the combination of the select signals SEL1 and SEL2 is detected by the thin line recognition processing circuit 21 to be within a predetermined pixel width, in this case, a logical sum is obtained by the OR gate 22 and the thin line recognition processing circuit 21 The signal can be output with priority, and the white signal forcibly added in the thinning processing circuit 20 can be forcibly changed to a black signal.
Fine lines and fine characters can be output as clear fine lines or fine characters without being partially deleted.

Further, by selecting an image processing mode such as the photographic processing circuit 12 or the simple binarizing circuit 13 by the mode selection means 30 provided on the panel of the stencil printing apparatus, a normal halftone dot or a silver halide photograph can be obtained. Image processing, character image processing, etc.

[0047]

As described above, according to the present invention,
By selecting an image processing mode such as a photo processing circuit or a simple binarizing circuit, it is possible to perform image processing of a halftone original such as a normal halftone dot or a silver halide photograph, and character image processing, and to recognize a thin line. By selecting the image processing mode of the processing means, fine lines and fine characters can be clearly output as images, and by selecting the image processing mode of the thinning processing means, the transfer amount of ink in the solid portion can be suppressed, and A printed matter without reflection can be obtained. Therefore, a high-quality output can be easily provided according to the image state of the document.

[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 device 3 Plate making means 12 Photo processing circuit 13 Simple binarization circuit 20 Thinning processing circuit 21 Fine line recognition processing circuit 22 OR gate 30 Mode selection means 40 CPU

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409

Claims (1)

(57) [Claims] An image processing apparatus having a photo processing circuit, a simple binarizing circuit, and the like, and processing an original read by a photoelectric conversion unit as an image signal of binarized data for each pixel, comprising: 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 corresponding to a continuous high density portion of the read original. On the other hand, thinning processing means for forcibly adding an image signal with a predetermined pixel interval to add a white signal, and respective images of the above-mentioned photographic processing circuit, simple binarization circuit, fine line recognition processing means, thinning processing means, etc. An image processing apparatus comprising: a mode selection unit that selects a processing mode.