JPH02302173A - Picture processing system - Google Patents

Abstract

PURPOSE:To obtain a magnified picture corresponding to a magnified size by using a readout clock with a frequency different from a frequency of a write clock so as to read out a picture data written in a storage means through the use of a prescribed write clock while applying repetitive processing. CONSTITUTION:A readout control circuit 6 reads out a picture data after repetitive processing via a selector 43 from line buffers 41, 42 as it is or while applying repetitive processing as required. A clock generating circuit. 7 consists of a couple of frequency dividers 71, 72 generating write and readout clocks. The frequency divider 72 generates a write clock synchronously with a picture input clock by applying 1/4 frequency division to the original oscillation clock, while the frequency divider 71 applies 1/3 frequency division to the original oscillation clock to generate the readout clock having a clock period with 75% of the write clock.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to an image processing device having an image enlargement function and used in facsimiles, printers, image scanners, etc. The present invention relates to an image processing method that enlarges image data in a predetermined scanning line direction while reading the data.

``Prior Art'' Conventionally, facsimiles and image scanners sometimes enlarge image data read by an image sensor to a predetermined size and transmit it to the other receiver, and laser printers and other page printers also enlarge the image data read by an image sensor and transmit it to the other receiver. In some cases, the image data developed in the memory is enlarged to a predetermined size and output to the print engine side, and one method for enlarging such image data to a predetermined size is, for example, by converting image data in a predetermined scanning line direction to a predetermined pixel clock. In a device that performs image processing while alternately writing and reading data into a plurality of line buffers based on frequency, pixel data located at intervals corresponding to a predetermined magnification ratio of image data is repeatedly read out during the reading process. There is a method for substantially increasing the number of pixels and enlarging one image data. (Unexamined Japanese Patent Publication No. 82-247E
i73 et al.) In a device that performs image processing while alternately writing and reading image data in a predetermined scanning line direction to a plurality of line buffers based on a predetermined pixel clock frequency, the writing (n) and reading Hours (m)
There is also a method of enlarging image data by varying the clock frequencies of the images and setting the frequency ratio (m/n) corresponding to the image enlargement rate. (Unexamined Japanese Patent Publication No. 59
-178863, etc.) ``Problem to be solved before generation'' However, in the former method of iteratively processing image data, there are cases where iterative processing is performed for every pixel as in A5-A3 (2001), or when the repetition rate is Many B5-e A
3 (1213%) and 85 mB4 (141%) (7), the image distortion is caused by WJ's current model, A4->84 (122%), because the repeated pixels are distributed almost equally. , :HaB5-eA4 (115%) As the magnification becomes smaller, the repetition rate decreases, so the repetition pixels are arranged unevenly in some parts, resulting in large image distortion and image distortion. Problems arise with reproducibility, etc.

In addition, in the latter technology, a configuration is adopted in which write and read clocks are generated using multiple clock generators with different frequency division ratios for the original oscillation clock, so in order to obtain a finer scaling ratio, the above-described The original oscillation clock for generating the write and read clocks must be made faster, which increases the cost of the device.

In view of the drawbacks of the prior art, the present invention provides an image processing method that can obtain an enlarged image that is preferable in terms of image reproducibility and legibility without causing significant image distortion even when the enlargement ratio is set to a small value. The purpose is to provide.

Another object of the present invention is to provide a vehicle that provides an image processing method capable of obtaining an enlarged image with high accuracy in correspondence with the variable size without increasing the speed of the original oscillation clock that generates the pixel clock.

``Means for Solving the Problems'' The present invention does not enlarge the image only through repetitive processing, and only by changing the clock frequency during writing (n) and reading (m). Instead, by combining the two, a write or read operation using a clock having a frequency different from the input clock of the original image data, and an iterative processing operation of the original image data, resulting in a two-stage scaling operation. By doing so, it is possible to cancel out the disadvantages of the re-operation and perform preferable image enlargement processing.

That is, in the present invention, for example, after data corresponding to an original image is written into a storage means using a write clock synchronized with an input clock of the original image data, the data corresponding to the original image is written using a read clock having a higher frequency than the write clock. By reading the image data from the storage means, an enlarged image of a desired magnification can be obtained by performing a repetitive processing operation at a repetition rate higher than the desired magnification while performing an apparent image reduction operation. That is.

"Operation" According to this technical means, since the iterative processing operation is performed while substantially reducing the image by the first operation, as a result, the iterative processing operation is performed at a repetition rate higher than the target image enlargement rate. As a result, B5-* A4 (115%
) Even if the magnification ratio is small, it is possible to distribute the repetition rate of each pixel almost equally, and as a result, image distortion does not become noticeable and the enlarged image is favorable in terms of image reproducibility and readability. can be obtained.

For example, if the ratio of the two clock cycles is set to 75%, the repetition rate can be set to 153% even when the image enlargement rate is 115%, and the repetition rate can be set to 163% when the image enlargement rate is 122%. This makes it possible to equalize the repetition rate between each pixel, thereby further achieving the above effect.

On the other hand, the read clock is not set to a different frequency from the write clock in order to set the image enlargement rate, but is simply set to increase the repetition rate of the repetitive processing operation, and therefore corresponds to the enlargement rate. There is no need to make the clock cycle variable by changing the clock cycle; a fixed clock cycle is sufficient.

That is, there is no need to vary the read clock period in accordance with the enlargement ratio, and as a result, there is no need to speed up the original oscillation clock for generating the write and read clocks, and there is no need to increase the speed of the original oscillation clock for generating the write and read clocks. Since only two frequency dividing circuits are required, it is possible to avoid complicating the device configuration.

In addition, when the period ratio of the read clock is set to 75%, if the readout is performed as is without performing any repetitive processing operation, 7.
An image reduced to 5% is obtained.

Therefore, if you want to obtain a reduction rate of 86% (A4-B5) or 81% (84mA4), you can repeatedly process the same pixel while reading it from the storage means using the readout clock, and the apparent enlargement process ( t3), and although this causes some image distortion, it is possible to obtain a reduced image with high readability because essential pixels are not missing unlike in the case of conventional thinning processing. Note that the reduction processing using the clock can be performed during a write operation.

Claim 4) is a claim that includes this point, and the result is obtained by combining a write or read operation using a clock having a frequency different from the input clock of the original image data and an iterative processing operation of the original image data. The present invention is characterized in that a variable magnification image with a desired magnification is obtained by performing a two-step variable magnification processing operation.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. It's nothing more than that.

FIG. 1 is an overall block diagram showing an image processing apparatus having an enlargement or reduction function according to an embodiment of the present invention.

1 is a video memory that stores, for example, image data corresponding to the true value expanded into dots, and when storing the image data, it is thinned out or repeatedly controlled in the sub-scanning direction in correspondence with a predetermined variable size. It is stored in this condition. (Since the magnification processing in the sub-scanning direction is not an essential part of the present invention, its explanation will be omitted.) 2 is a control unit that controls the image data stored in the video memory 1 every -1 scan or every n bits. After being read out to the shift register 21 in parallel, the pixel data in the shift register 21 is sequentially shifted based on the write clock generated by the clock generation circuit 7 and is configured to be serially output to the temporary storage means 4 side. .

The temporary storage means 4 consists of two sets of line buffers 41 and 42 that perform toggle operations and a selector 43, and switches the selector 43 alternately for each scanning line based on the main scanning synchronization signal to Writing and reading from the line buffers 41 and 42 are performed in parallel based on the write clock and read clock generated by the line buffers 41 and 42.

6 is a selector 43 from the line buffer 41.42.
This is a readout control circuit that reads out the image data after iterative processing via the N-bit shift register 61 and the desired image enlargement ratio, as shown in FIG. a repetition designation circuit 60 that sends out a repetition designation signal to
It consists of an iterative control circuit B2 that repeatedly reads out corresponding pixel data output from the pixel data.

7 is a clock generation circuit consisting of a pair of frequency dividers 71 and 72 that generate write and read clocks, and by dividing the original oscillation clock by 4 using each frequency divider 72, a write clock synchronized with the image input clock is generated. is,
On the other hand, by dividing the original oscillation clock by three using the frequency divider 71, a read clock having a clock period of 75% of the write clock is generated.

According to such embodiments, the effects of the present invention described above can be smoothly achieved.

That is, in this embodiment, the original image data stored in the shift register in the control unit (video memory) is stored as it is in the temporary storage means using a write clock synchronized with the image input clock, and then the write clock 751 of the write a Since the configuration is such that the readout control circuit performs repetitive processing while reading based on the readout clock set to the period, the number of repetitions performed by the repetition control circuit 3 is made larger than the actual magnification rate by the clock period ratio. Can be set.

For example, as described above, even when the image enlargement rate is 5z, the repetition rate can be set to 153z, and when the image enlargement rate is 122%, the repetition rate can be set to 183z.

Note that the clock cycle ratio is 88% or 81%, which is greater than 75%.
As mentioned above, even when it is desired to obtain a reduction rate of 1.5%, the above-mentioned apparent enlargement processing can be performed using the iterative control circuit as described above.

"Effects of the Invention" As described above, according to the present invention, even when the magnification ratio is set to a small value, it is possible to obtain an enlarged image that is preferable in terms of image reproducibility and legibility without noticeable image distortion. In addition, even if a read clock having a frequency different from that of the write clock is used, there is no need to increase the speed of the original oscillation clock that generates the pixel clock, and as a result, the device configuration is simplified.

It has various effects such as

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an image processing device for image enlargement according to an embodiment of the present invention. FIG. 2 is a block diagram showing a read control circuit used in the processing device.

Claims (1)

[Claims] 1) In an image processing method that enlarges image data in a predetermined scanning line direction while writing to and reading from a storage means at a predetermined clock, the image data written to the storage means using a predetermined write clock is An image processing method characterized in that an enlarged image of a desired magnification is obtained by repeatedly reading image data using a read clock having a frequency different from that of the write clock. 3) The image processing method according to claim 1, wherein the read clock is a clock synchronized with an input clock, and the read clock has a higher frequency than the write clock. 4) Image processing method according to claim 1), characterized in that enlarged images with different magnifications are obtained by changing only the number of repetitions. 4) Image data in a predetermined scanning line direction while being written to and read from the storage means at a predetermined clock. In an image processing method for enlarging images, a combination of a write or read operation using a clock having a frequency different from the input clock of the original image data and an iterative processing operation of the original image data results in a two-step scaling process. An image processing method characterized by obtaining a variable magnification image of a desired magnification by performing operations.