JP3651396B2 - Image processing circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing circuit that performs smoothing processing and resolution conversion.
[0002]
[Prior art]
In general, as one of image processes, a smoothing process is often performed in order to make pixels appear smoother. Smoothing is often performed together with resolution conversion. For example, when converting 200 dpi resolution to 400 dpi, one pixel is replaced with four pixel data for all of the original pixel data (200 dpi). However, when the resolution conversion is not an integral multiple, for example, when converting 400 dpi to 600 dpi, one pixel data is replaced with four pixel data in a pixel with original pixel data (conversion in the main scanning and sub-scanning directions). In the next pixel, one pixel data is replaced with one pixel data. In that case, in order to make the smoothing circuit common to the two processes, the same smoothing pattern is applied, and in the case of conversion in both scanning directions, four pixels are output. Of these, only one specific pixel is output.
[0003]
[Problems to be solved by the invention]
As described above, in resolution conversion that is not an integral multiple, a method of outputting four pixels in the case of conversion in both scanning directions, and outputting a specific one of the four pixels in the case of no conversion Then, depending on the arrangement of the four pixels to be replaced, there is a disadvantage that the black pixels of the original image data are replaced with white pixels (or vice versa).
[0004]
For example, when the original image is (a) in FIG. 6, paying attention to the pixel at the center of the 3 × 3 pixels, this pixel is replaced with four pixels, and the pixel data shown in (b) in FIG. When outputting as four pixels, only the third pixel is output as a black pixel. However, since the first white pixel is output when it is output as one pixel, the converted image is a white pixel at the center pixel as shown in FIG. It is different from that of black / white.
[0005]
The present invention has been made paying attention to the above problems, and in the case of performing resolution conversion that is not an integral multiple, an image processing circuit that can prevent white / black from being reversed for pixels that are not subjected to resolution conversion. It is intended to provide.
[0006]
[Means for Solving the Problems]
The image processing circuit of the present invention is a selection circuit that selectively outputs pixel data and original pixel data that have undergone resolution conversion and smoothing in a circuit that performs resolution conversion and smoothing processing by matching with a predetermined pattern. When performing resolution conversion that is not an integral multiple, the selection circuit selects pixel data that has been subjected to resolution conversion and smoothing for pixels for which resolution conversion is to be performed, and original pixel data for pixels that are not to be subjected to resolution conversion. I am trying to select it.
[0007]
In the image processing circuit is provided with selection circuits, when converting the resolution is not an integral multiple, for pixels perform a selection circuit resolution conversion, selects the resolution conversion and smoothing processed pixel data, performing resolution conversion For pixels that do not exist, the original pixel data is output. For pixels that are not subjected to resolution conversion, the original pixel data is output, so that the pixel data is not inverted black and white.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0009]
FIG. 1 is a block diagram illustrating a schematic configuration of a combined apparatus having a copy function and a facsimile function including an image processing circuit according to the embodiment. This composite device includes a CPU (control unit) 1, NCU 2, modem 3, scanner 4, operation unit 5, ROM 6, RAM 7, image memory (DRAM) 8, CODEC 9, DMAC (direct memory access controller) 10, matching A printer image processing circuit (image data processing unit) 11 having a pattern RAM 12, a line memory (FIFO) 13, a DMAC 14, and a printer (image forming unit) 15 are provided. These elements are connected by a system bus 19 and an image bus 20.
[0010]
CPU1 controls each part which comprises this apparatus.
[0011]
The NCU 2 controls a connection with a telephone line (not shown), and has a function of transmitting a dial signal corresponding to a telephone number (including a FAX number) of a destination and a function of detecting an incoming call. . The modem 3 is an ITU (International Telecommunication Union) -T recommendation T.264. 30 based on the facsimile transmission control procedure according to 17, V. 27ter, V.I. The transmission data is modulated and the received data is demodulated in accordance with 29.
[0012]
The scanner 4 reads image data of a document when performing FAX transmission and copying. The operation unit 5 is used by the user to instruct FAX transmission / reception, printing, and the like when using the facsimile function or the copy function.
[0013]
The ROM 6 stores a program for controlling this apparatus. The RAM 7 temporarily stores data and the like. The image memory 8 temporarily stores the received image data and the image data read by the scanner 4 in a compressed state. The CODEC 9 encodes (encodes) the read image data by the MH, MR, MMR method, etc., and decodes the received image data. The DMAC 10 is used to transfer image data stored in the image memory 8 to the CODEC 9 and is activated by the CPU 1.
[0014]
The printer image processing circuit 11 performs smoothing processing and resolution conversion on the input pixel data, and supplies the pixel data to the printer 15. The matching pattern RAM 12 stores a plurality of pattern data for matching with original pixel data for smoothing and resolution conversion.
[0015]
FIG. 2 is a block diagram illustrating a circuit configuration of the printer image processing circuit 11. The printer image processing circuit 11 includes a comparator 21 that sequentially compares original pixel data from the line memory 13 and a matching pattern read from the matching pattern RAM 12, an image data memory 22 that stores smoothed image data, and image data. A selector (selection circuit) 23 that selects and outputs either smoothing and resolution-converted pixel data stored in the memory 22 or original pixel data stored in the line memory 13, and writing to the line memory An address counter 24 for counting read addresses is provided.
[0016]
FIG. 3 is a circuit diagram more specifically showing the logic circuit configuration of the comparator (comparison circuit) 21 of FIG. FIG. 4 shows image data input to the comparator 21. 4A shows the original image data in 3 rows and 3 columns, and shows the center pixel of interest and surrounding pixels A, B,... FIG. 4B shows a matching pattern of 3 rows and 3 columns, which is also the pixel of interest at the center in 3 rows and 3 columns and surrounding pixels a, b,. As for this matching pattern, a plurality of pixels a, b,..., H having different logic states are stored in the matching pattern RAM 12.
[0017]
Here, the comparator 21 includes eight AND circuits 25a, 25b,..., 25h, and one AND circuit 26. The pixel A of the original image data and the pixel a of the matching pattern are input to the input of the AND circuit 25a, and the pixel B of the original image data and the pixel b of the matching pattern are input to the input of the AND circuit b. Pixels C and c,..., Pixels H and h are input to the inputs of the AND circuits 25c,. Each output of the AND circuits 25a, 25b,..., 25h is applied to an input of the AND circuit 26.
[0018]
In the printer image processing circuit 11, when the read original image data and the first matching pattern read from the matching pattern RAM 12 are input from the line memory 13 based on the address counted by the address counter 24, the comparator 21 Both data are compared and matching processing is performed. If the data of the original pixels A,..., H shown in FIG. The converted data is used as a conversion pixel of the central pixel, and is stored in the image data memory 22 as smoothed data together with the surrounding data.
[0019]
Now, assuming that a 400 dpi image is converted to a 600 dpi resolution and output, and the original original image data is, for example, as shown in FIG. As shown in FIG. 5B, the original image has four pixels as the original center pixel, and here, only one pixel (indicated by 3) is a black pixel. If the selection signal applied to the selector 23 is a signal for increasing the number of pixels, (b) in FIG. 5 is selected, that is, the original central pixel portion increased to four pixels stored in the image data memory 22 is selected. The image data shown in FIG. 5C is output to the printer 15.
[0020]
On the other hand, when the selection signal applied to the selector 23 does not increase the number of pixels, the original image data stored in the line memory 13, that is, the pixel data of FIG. 5A is as shown in FIG. The data is output to the printer 15 as it is. The central pixel shown in (d) of FIG. 5 is black, which is the same as the original pixel black, and black / white inversion does not occur.
[0021]
In the above embodiment, the matching pattern and the like have been described as a 3 × 3 matrix, but the present invention can also be applied to a matrix having other number of matrices such as 5 × 5.
[0022]
【The invention's effect】
According to the present invention, the selection circuit that selectively outputs the pixel data subjected to resolution conversion and smoothing processing and the original pixel data is provided, and when performing resolution conversion that is not an integral multiple, the selection circuit performs the pixel conversion for the resolution conversion. selects the resolution conversion and smoothing processed pixel data, the pixel is not performed resolution conversion, since so as to select the original pixel data, the pixel is not performed resolution conversion, the original pixel data Since the output is performed, it is possible to prevent the white / black from being reversed, and to prevent the image quality from being deteriorated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a facsimile machine with multiple functions according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a printer image processing circuit of the facsimile apparatus with combined functions according to the first embodiment.
FIG. 3 is a block diagram illustrating a logical circuit configuration of a comparator of the printer image processing circuit.
FIG. 4 is a diagram illustrating original image data and a matching pattern of the printer image processing circuit.
FIGS. 5A and 5B are diagrams for explaining processing in the printer image processing circuit when resolution is increased and when pixels are not increased. FIGS.
FIG. 6 is a diagram for explaining processing in a case where the number of pixels is not increased in resolution conversion of a conventional apparatus.
[Explanation of symbols]
11 Printer Image Processing Circuit 12 Matching Pattern RAM
13 Line memory 15 Printer 21 Comparator 22 Smoothing image data memory 23 Selector

Claims (1)

In an image processing circuit that performs resolution conversion and smoothing processing by matching with a predetermined pattern,
A selection circuit that selectively outputs pixel data and original pixel data that have undergone resolution conversion and smoothing processing is provided, and when performing resolution conversion that is not an integral multiple, the selection circuit performs resolution conversion and smoothing for pixels that are subjected to resolution conversion. An image processing circuit that selects processed pixel data and selects original pixel data for a pixel that is not subjected to resolution conversion.

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