JPH07273986A - Method and device for image processing - Google Patents

Abstract

PURPOSE:To improve the picture quality of a binary image in addition to the gradations of a multi-valued image. CONSTITUTION:An inputted image is inputted to an image processing circuit 107 by a switching/converting circuit 106 after being converted by a processing method into density data in case of multi-valued data or into many-valued or pattern data in case of binary data. Then the multi-valued or pattern data are processed at need and outputted to an image formation block 102. In case of the multi-valued data, a 1st image forming circuit 108 is used to output the data to a laser 111 and in case of the pattern data, a 2nd image forming circuit 109 is used to output the data to the laser 111, thereby forming an image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus for performing optimum image processing on input binary or multi-valued image data and outputting it.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a general image processing apparatus. In the figure, 301 is an image control block, 302 is an image forming block, and 303 to 3
Reference numerals 05 are functional blocks such as a FAX, a scanner, and a printer.

In the image control block 301, 306
Is a switching / converting circuit for switching the image data input from each of the functional blocks 303 to 305, and if the input data is binary data, converting it to a multi-valued image of 0 or 255, and 307 An image processing circuit that performs image processing.

In the image forming block 302, 308
Is an image forming circuit for performing area modulation of a laser based on density data, 309 is a laser, and is composed of a printer such as a photosensitive drum (not shown).

FIG. 4 is a diagram showing the image forming circuit 308 of FIG. 4, 401 is a D / A conversion circuit for converting the input 8-bit density data into a voltage level, 402 is a triangular wave generation circuit, and 403 is a D / A conversion circuit 401 and a triangular wave generation circuit. It is a comparator circuit for comparing the output of 402.

FIG. 5 is a timing chart showing these operations, 501 is an image transfer clock, and all pixel data are transferred in synchronization with this clock. Reference numeral 502 denotes an output of the D / A conversion circuit 401 shown in FIG. 4, which outputs a voltage level corresponding to the input density data. Reference numeral 503 denotes a triangular wave output from the triangular wave generation circuit 402. Reference numeral 504 is an output of the comparator 403, which is also a laser on / off signal.

Next, the operation of the above configuration will be described.

First, from the functional blocks of the scanner, etc., 30
When image data is input to the first image control block, the image data is converted into density data by the switching / converting circuit 306, and desired image processing is performed by the image processing circuit 307. Then, in the image forming block 302,
The density data is area (PWM) modulated by the image forming circuit 308 and output to the laser 309. Specifically, 40
The D / A converter 1 converts the multi-bit density data into a voltage level, and the comparator 403 compares it with the triangular wave 402 to perform PWM modulation.
By turning on / off the laser with the modulated density data, it is possible to form an output image having gradation for all pixels.

When converting the data amount such as image reduction or enlargement, the image processing circuit 307 performs desired processing. For example, as shown in FIG. 6, 80h and 20
When two pixels having a density of h are changed to three pixels, a method of inserting an average value of both as a pixel in between is generally used.

When the input image data is binary data, the switching / converting circuit 306 converts each binary pixel of 1 or 0 into density data. That is, in the case of a system having 8-bit gradation as density data, the maximum density is FFh for input 1 and the minimum density is 00h for input 0.

There are the following two methods for converting the input binary data into the data amount such as reduction or enlargement.

1) After converting the data amount of binary data, it is converted into density data.

2) After converting the density data, the data amount is converted by the method described above.

FIG. 7 is a diagram showing an example in which binary data is enlarged by 3/2 times.

[0015]

However, in the above-mentioned conventional example, the PWM modulation of the laser is originally for reproducing the density, the resolution is fixed by the transfer clock, and the density of each pixel is the center point. From area modulation. Therefore, there has been a problem that it is not possible to improve the resolution with respect to the stepwise change of dots by adjusting the laser on / off timing, which is a smoothing method that has become mainstream in recent years in a binary image processing system. .

Further, when the data amount conversion is performed on the binary data, there is also a problem that dots of halftone density are generated at the edges and the image is deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image processing method and apparatus in which the image quality of a binary image is improved in addition to the gradation of a multivalued image. And

[0018]

In order to achieve the above object, the image processing apparatus of the present invention has the following configuration.

That is, an image processing apparatus for performing optimum image processing on input binary or multi-valued image data and outputting the image data, the first processing means processing the input image data as density data. Second processing means for processing the input image data as pattern data, and output means for outputting the image data processed by the first or second processing means.

Further, the image processing method according to the present invention has the following steps.

That is, a first processing step of processing the input image data as density data, which is an image processing method for performing optimum image processing on the input binary or multi-valued image data and outputting the image data. A second processing step of processing the input image data as pattern data, and an output step of outputting the image data processed by the first or second processing step.

[0022]

With this configuration, the input binary or multi-valued image data is processed as density data or pattern data and output.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of an image processing apparatus according to this embodiment. In the figure, 101 is an image control block, 102 is an image forming block, and 1
Reference numerals 03 to 105 are functional blocks such as a FAX, a scanner, and a printer.

In the image control block 101, 106
Is a switching / converting circuit for switching the image data input from each of the functional blocks 103 to 105 and for converting the input data to be binary data into a multivalued image of 0 or 255. An image processing circuit that performs image processing.

In the image forming block 102, 108
Is a first image forming circuit that performs area modulation of the laser based on the density data, 109 is a second image forming circuit that controls the laser based on the pattern data, and 110 is a first and second image forming circuit. A selector (SEL) for switching and selecting, 111 is a laser, and is composed of printer components such as a photosensitive drum (not shown).

FIG. 2 is a diagram showing the configuration of the second image forming circuit 109 shown in FIG. In FIG. 2, reference numeral 201 is a parallel input / serial output shift register, 202 is 8-bit image data input from an image control block, and 203 is an operation of the shift register 201 in synchronization with an image transfer clock. Is a load signal for input from a timing generation circuit (not shown). Reference numeral 204 denotes a clock for dividing an original pixel into eight and outputting the same, which is input at a frequency eight times as high as the image transfer clock. 205 is the output of the shift register 201.

Next, the operation principle of the above-mentioned structure will be described below.

First, the image input from each functional block is converted by the switching / converting circuit 106 into density data in the case of multi-valued data, and into multi-valued or pattern data in the case of binary data by the processing method. It is input to the image processing circuit 107. Then, the multi-valued or pattern data is subjected to image processing as necessary and output to the image forming block 102. 1 for multi-valued data
The first image forming circuit 08 is used to output to the laser 111, and in the case of pattern data, the second image forming circuit 109 is used to output to the laser 111 to form an image.

Next, case classification according to the input image and the image processing method will be described.

(1) When a multi-valued image is input When a multi-valued image from a scanner or the like is input, an image processing circuit 107 performs buffering and the like, and then the density data 108 To the image forming circuit, and controls the laser of 111 through the selector of 110 to output an image.

Further, in this case, in the process of changing the data amount such as resolution conversion or reduction or enlargement, as shown in FIG. 6, the process using the density data is performed. FIG. 6 shows 80
2 pixels of h and 20h are divided into three, and 80h, 50h and 20
This is the case when h is set.

(2) When a binary image is input and output as a multi-valued image (conventional method) When a binary image of a printer or the like is input, it is buffered by the image processing circuit 107 and converted into density data. After the processing, the density data is sent to the second image forming circuit 108, the laser 111 is controlled through the selector 110, and the image is output. That is, in the case of a system having 256 gradations of 8 bits, the input binary data is 25
Converted to 5 or 0 and processed.

Further, in this case, in the process of changing the data amount such as resolution conversion and reduction or enlargement, since the process using the density data is performed, the data which was originally 255 or 0 is converted into halftone data. In some cases. Figure 7
It is a figure which shows the case where ffh and 00h are divided into 3 and it is set as ffh, 80h, and 00h.

(3) When a binary image is input and output as a binary image (method of this embodiment) When a binary image of a printer or the like is input, the image processing means 107 performs processing such as buffering. After that, when the data is output to the image forming block 102, it is input to the second image forming circuit 109 as 8-bit pattern data as well as on or off binary data using a spatial filter. By doing so, it is possible to form an image with 8 times the resolution.

Further, in this case, in the process of changing the data amount such as resolution conversion or reduction or enlargement, the dot is divided into eight by a method such as pattern matching and the image is output using the second image forming circuit. FIG. 8 is a diagram showing a case where ffh and 00h are divided into three parts, which are ffh, f0h, and 00h.

As described above, according to this embodiment, the first image forming circuit has the method of handling the image data as the density data and the method of handling it as the pattern data, and expresses the gradation of the density data by the area modulation. And the second image forming circuit capable of dividing the pixels by the pattern data, it is possible to form an optimum image according to the type of the input image data.

<Modification> The modes described in (1) to (3) in this embodiment are binary data for a printer and multi-value data for a scanner, for each input system. As described above, there are cases where the input system is used for the determination, and for example, a printer also outputs a natural image as a bit image. Therefore, two methods are conceivable when switching is performed by a command from the operation panel or host.

Further, in the present embodiment, when a plurality of 107 image processing circuits are provided and images are superimposed, 10
A system in which the first and second image forming circuits 8 and 109 are operated in parallel is also conceivable. In that case, 11 shown in FIG.
0 may be an OR operation circuit instead of a selector.

Further, in the present embodiment, the data amount conversion method of the multi-valued image has been described as an example, but this is merely an example for convenience of operation description, and the method of processing multi-valued data such as the interpolation method is It does not impose any restrictions on the invention.

In the present embodiment, the laser control was described as an example of the image forming block, but this is also an example for the sake of convenience of explanation, and the laser control is possible if the gist of the present invention is realized. Other printer systems such as LEDs may be used.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. It goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0043]

As described above, according to the present invention,
In addition to the gradation of the multi-valued image, the image quality of the binary image can be improved.

[0044]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus in this embodiment.

FIG. 2 is a diagram showing details of a second image forming circuit shown in FIG.

FIG. 3 is a block diagram showing a configuration of a general image processing apparatus.

4 is a diagram showing a configuration of an image forming circuit shown in FIG.

5 is a timing chart illustrating the operation of the circuit shown in FIG.

FIG. 6 is a diagram illustrating an operation of enlarging density data to 3/2 times.

FIG. 7 is a diagram illustrating an operation of enlarging multi-valued data to 3/2 times.

FIG. 8 is a diagram illustrating an operation of enlarging pattern data to 3/2 times.

Claims (6)

[Claims] 1. An image processing apparatus for performing optimum image processing on input binary or multi-valued image data and outputting the image data, wherein the input image data is processed as density data.
And a second processing means for processing the input image data as pattern data, and an output means for outputting the image data processed by the first or second processing means. Image processing device. 2. The image processing apparatus according to claim 1, wherein the second processing means, when the input image data is a binary image, converts the image data into pattern data and performs pattern matching processing. 3. The image processing apparatus according to claim 1, wherein the output means outputs in parallel the image data processed by the first or second processing means. 4. The image processing apparatus according to claim 1, wherein the first and second processing means are respectively selected according to the input binary or multi-valued image data. 5. The image processing apparatus according to claim 1, wherein the first and second processing means are selected by a command from an operation panel or an external information processing apparatus. 6. An image processing method for performing optimum image processing on input binary or multi-valued image data and outputting the image data, wherein the input image data is processed as density data.
And a second processing step of processing the input image data as pattern data, and an output step of outputting the image data processed by the first or second processing step. Image processing method.