JPS621370A - Image processing method for digital copying machine or the like - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a black framed copy by detecting the timing of the first white data and that of the last white data in each one-line components of picture data and judging these read lines to be original edge parts and setting data on the outside of them to white data. CONSTITUTION:A flip flop 12 is reset when white data is inputted as picture data, and an up-counter 14 detects the timing of the first white data through an AND gate 13. When one-line components of data are terminated, an up- counter 15 detects the timing of the last white data through a latch 16. A comparator 20 outputs white data whose number corresponds to the number of clocks before the timing of the first white data, and a comparator 22 outputs white data whose number corresponds to the number of clocks after the timing of the last white data. Outputs of comparators 20 and 22 pass an OR gate 23, and the output where data in the part other than the original is inverted to white data is obtained from a gate circuit 26.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image processing method for digital copying machines, facsimile machines, etc. that digitally processes original images.

BACKGROUND ART Conventionally, in a typical analog copying machine, when the transfer paper is larger than the original, a white original pressure plate is used to prevent the outside of the original from being copied in black. On the other hand, in digital copying machines, rather than making the document pressure plate white, it has a mirror surface.

Light from outside the original does not enter the light receiving section, so that the light is the same as the black image area. This is to leverage the benefits of digital processing, such as detecting the edge of the document, determining its size and position, and moving the document even if it is not in the specified position on the contact glass. .

Such functions include, for example, the document position/size detection function in the Canon laser copying system NP-9030;
This is known as an automatic paper selection function. but.

In such a process, the outside of the original is considered black, so unless the edge of the original is accurately detected, the copy will have a black frame outside the original.

In this regard, the products mentioned above! X at the white point on the manuscript.

The minimum and maximum values of the Y coordinate are detected, and all image data outside these values is inverted to white. However, if you use this method.

It can only be processed after all images of the original have been read. For this reason, for example, when the original 1 is set obliquely on the contact glass 2 as shown in FIG. Since selective copying is performed, the resulting copy paper 4 has a black frame copy portion 6 outside the original image 5, as shown in FIG. 4(b). ,
: As a result, the copy quality deteriorates. Therefore, in order to prevent black border copies from occurring, the operator is required to be extremely careful when setting the original.

This results in poor copying efficiency.

Purpose The present invention has been made in view of the above points, and even when the original is set diagonally, the outer part of the original does not become a black frame copy, and the original is set with great care. An object of the present invention is to provide an image processing method for a digital copying machine, etc., which does not require special attention.

Structure In order to achieve the above object, the present invention provides a digital copying machine or the like that sequentially digitally reads an original image line by line using a light receiving unit and outputs image data via a 1-line buffer, and which outputs image data outside the original. When inputting image data to one line buffer, the timing at which white data appears first and the timing at which white data appears last in one line of image data is detected, and the timing at which white data appears last is detected. The present invention is characterized in that, when outputting image data from a line buffer, all image data before the timing at which white data appears first and after the timing at which white data appears last are output as white data.

Hereinafter, one embodiment of the present invention will be described based on the drawings. First, a one-line buffer 11 is provided to which one line of image data DATA read line by line by a CCD or the like in a digital scanner is input. Here, as shown in FIG. 2, this image data DATA is one pixel data generated every reference clock signal CLK corresponding to one pixel under the control of the synchronization signal LINE of one main scanning line, and the clock signal CLK It is stable at the rise of . Then, the L level corresponds to black, and the H level corresponds to black.
Level corresponds to white. Here, when looking at the image data DATA shown as an example in FIG. 2, it can be seen that the outside of the document is processed as black data, as explained in the conventional example.

However, if this image data DATA is output as is, a black frame copy may occur.

However, in this embodiment, measures are taken to prevent the occurrence of such black border copies.

First, a flip-flop 12 is provided to which the image data DATA is input. This flip flop 1
2 is set when H level white data is input for the first time as image data DATA. Therefore, an H level signal is output from between the output terminals of the flip-flop 12 until one image data DATA becomes white data for the first time. Here, an AND gate 13 to which the output from the output terminal τ and the clock signal CLK are input is provided, and an up counter 14 for counting the number of outputs from the AND gate 13 is provided.

As a result, this up counter 14 receives the synchronization signal LIN.
The number of pulses of the clock signal CLK until the image data DATA becomes white data for the first time in one line reading started based on E is counted. The timing at which white data is first output is detected based on the number of pulses counted in this manner.

On the other hand, an up counter 15 that sequentially counts up the clock signal CLK is also provided. A latch 16 is connected to this up counter 15, and the image data D
The number of clocks counted by the up counter 15 is set in this latch 16 every time white data is generated in the ATA. Therefore, at the end of one line of data, the number of clocks at which the image data DATA became white data is set in the launch 16. The timing at which white data is finally output is detected by the number of clocks set in this latch 16.

In this way, reading of one line is completed, and at the start of scanning of the next line, the value of the up counter 14 is set to the preset counter 17 by the rise of the line synchronization signal LINE, and the value of the launch 16 is set to the latch 18. Set. Then, when the line synchronization signal LINE falls, the up counters 14 and 15 and the latch 16 are reset. At this time, like the up counter 15, the up counter 19 that counts the number of clocks is also reset.

Then, the same process as described above is repeated for the next line of image data DATA started based on the line synchronization signal LINE, and at the same time, the value of the preset counter 17 for the previous line is changed to the clock signal CLK.
-1 each time.

The comparator 20 compares the value until it becomes 0, and outputs 1 (H level as white data). In other words, it is the number of clocks before the timing when white data is first output. Incidentally, when the value of the preset counter 17 reaches 0, a 0 output is returned to the AND gate 21 provided on the input side of the preset counter 17 so that it does not further decrease by 1. Also, the value set in the latch 18 is the clock signal CL.
The comparator 22 compares the value of the up counter 19 that continuously counts K, and when the number of clocks exceeds the value set in the latch 18, the comparator 22 outputs 1 (H level as white data). Output. In other words, it is the number of clocks after the timing when the last white data is output.

Outputs from these comparators 20 and 22 are input to an OR gate 23. Therefore, this OR gate 23
An output of 1 (=H level) corresponds to the clock signal CLK before the timing when white data is first output and after the timing when white data is output last. Therefore, the output of this OR gate 23 and the unprocessed 1 of one line
Exclusive OR gate 2 with Deba from line buffer 11
4 and an OR gate 25, an output is obtained in which all data outside the document is inverted to white data, as shown as output data in FIG. Since such processing is performed for each line in real time, even if the original is set diagonally on the contact glass, the outside of the original will not be copied with a black border.

Note that when all of the image data DATA of one line is black data, the up counter 14 is set to the total number of pixels of one line, so that all of the one line is inverted to white data. Of course, if one line of image data DATA is all black data, such as when the leading edge of the document is misaligned, such inversion processing is sufficient, but if there is actually a black line image in the center of the document, etc. If this is used as white data, the image will be lost. To prevent this, if the flip-flop 12 is not set while processing the center part of the document (in other words, if white data does not appear)
Inversion to white data may be prohibited.

Effects As described above, the present invention detects the timing at which white data appears first and last for each line of image data, and determines the timing positions at which this white data appears at the beginning and end as the document edge portion of that reading line. As a result, the outer part of the image data output from the 1-line buffer is treated as white data, so even if a 1M document is set diagonally, it can be processed in real time. This makes it possible to prevent black border copying from occurring in areas outside the original.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart, and FIGS. 3(a) and 3(b) are plan views showing a conventional example. 11...1 line buffer

Claims (1)

[Claims] In a digital copying machine or the like that sequentially digitally reads an original image line by line by a light receiving unit and outputs image data via a 1-line buffer, the image data outside the original is read as black data. When inputting image data to the line buffer, the timing at which white data appears first and the timing at which white data appears last in one line of image data is detected, and when image data is output from the one line buffer, white data appears first. An image processing method for a digital copying machine or the like, characterized in that all image data before the timing when white data is output and after the timing when white data is finally output are output as white data.