JPS6255779A - Smoothing circuit - Google Patents

Abstract

PURPOSE:To obtain pictures of high quality and to facilitate following processes by using a direction extracting means which divides a linear picture into several local areas and extracts the direction of the line for each local area and a smoothing means which scans and smoothes those local areas in accordance with the directions of lines extracted by the direction extracting means. CONSTITUTION:Pictures equivalent to a screen stored in a frame memory 1a are divided into several parts and a direction extracting means 7 extracts the directions of lines and stores them in a direction memory 8. When a direction selecting signal 10 indicates the direction (k), an address counter 2 produces an address so that the screen is scanned in the direction (k). Then the picture data on the memory 1a are sent successively to a shift register 4 in the scan direction. The means value of the picture data equivalent to (n) picture elements of the scan direction, that is, the smoothed picture data are delivered through an adder 5 and a divider 6. If coincidence is obtained under such conditions between the line direction of the local area and the direction of the signal 10, the smoothed picture data are written on a frame memory 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a smoothing circuit that smoothes a linear image having a locally fixed direction.

[Conventional technology]

FIG. 4 is a diagram showing a conventional smoothing circuit. In the figure, la and lb are frame memories that store one screen of image data, and 2 is a frame memory la.

3 is a timing control circuit that controls the operation of address counter 2;
4 is a shift register that temporarily stores image data sent from the frame memory la; 5 is an adder that calculates the sum of the image data in each stage of shift register 4; and 6 is a divider that divides the output of adder 5 by the number of stages of shift register 4. It is a divider.

Next, the operation will be explained. When smoothing one screen of image data stored in the frame memory 1a, the address data generated by the address counter 2 is sequentially sent to the shift register 4, and the image data in the frame memory corresponding to the address data is shifted. Temporarily stored in register 4. In this case, the timing control circuit 3 normally controls the address counter 2 so that one screen is scanned horizontally upward or downward. Therefore, if the number of stages of the shift register 4 is n, the sum of image data for n pixels in the horizontal direction is determined by the adder 5, and this is divided by n by the divider 6 to form an area of n×1 pixels. The average value of the image data is determined. By writing this into the frame memory 1b, a smoothed image can be obtained.

[Problem that the invention seeks to solve]

Line images such as fingerprint images often have places where the lines are broken or where adjacent lines are loose, but conventional smoothing circuits usually only smooth in the horizontal direction. Since it is a scanning method, if the line is oriented in a direction other than horizontal, it may not be possible to sufficiently remove line breaks, loose spots, etc.
There was a problem that it adversely affected subsequent processing.

This invention was made to solve this problem, and it divides one screen image into several local areas, extracts the direction of the line for each local area of i, and creates an image corresponding to that direction. By smoothing the lines, the purpose is to remove breaks and gaps in the lines and obtain a high-quality smoothed image.

[Means for solving problems]

The smoothing circuit according to the present invention includes a direction extraction means that divides a linear image into several local regions and extracts the direction of the line for each divided local region, and a direction of the line extracted by the direction extraction means. The present invention is characterized by comprising a smoothing means for scanning and smoothing a local area in accordance with the above.

[Effect]

The direction extraction means divides the linear image into several local regions and extracts the direction of the line for each divided local region.

The smoothing means scans and smoothes the local region in accordance with the direction of the line extracted by the direction extraction means.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.
6 is the same as the conventional device. 7 is a direction extracting means for extracting the direction of a line in each local area obtained by dividing the image stored in the frame memory 1a into several parts; 8 is a direction memory for storing the direction extracted by the direction extracting means 7; 9 is a direction extracting means for extracting the direction of a line; is a write control circuit that sends a write control signal to the frame memory 1b to write smoothed image data when the direction indicated by the direction selection signal lO matches the direction of the line of the extracted local area. be.

Here, frame memories la, lb, address counter 2, timing control circuit 3, shift register 4, adder 5, and divider 6 constitute smoothing means 12.

An embodiment of the present invention will be described below with reference to the drawings. First, one screen image stored in the frame memory 1a is divided into several parts as shown in FIG. (In this case, the direction is quantized and stored in eight directions as shown in FIG. 3. When the direction selection signal 10 represents the direction k (k=l, ..., 8), The address counter 2 generates addresses so as to scan the screen in the scanning direction, and the image data in the frame memory la is sent to the shift register 4 one after another in the scanning direction.The average of the image data for n pixels in the scanning direction is The value, that is, the smoothed image data, is outputted through an adder 5 and a divider 6.

At this time, the direction of the line of the local area containing the address is
When the direction coincides with the direction indicated by the direction selection signal lO, the write control circuit 9 outputs the write control signal 11, and the smoothed image data is written into the frame memory 1b. In this way, the smoothing means 12 obtains a smoothed image in a local area where the line direction is k. In this case, by changing k from 1 to 8 and repeating the above-described scanning, smoothing will be performed corresponding to the direction of the line in each local area.

Note that in the above embodiment, smoothing is performed using the average value of image data in an area of y+x1 pixels, but by further adding a shift register and an adder, smoothing is performed using the average value of image data in an area of nxm pixels. You can also.

Further, the above embodiment can be used not only for fingerprint images but also for preprocessing linear images such as drawings and characters.

〔Effect of the invention〕

As explained above, according to this explanation, there is a direction extraction means that divides a linear image into several local regions and extracts the direction of the line for each divided local region, and Since the present invention includes a smoothing means for scanning and smoothing a local area in accordance with the direction of the line, a higher quality image can be obtained and subsequent processing is easier.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a smoothing circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing division of one screen, FIG. 3 is a diagram showing the direction in which the screen is scanned, and FIG. 4 is a diagram showing the conventional method. FIG. 2 is a diagram showing a smoothing circuit of FIG. In the figure, 1 is a frame memory, 2 is an address counter, 3 is a timing control circuit, 4 is a shift register, 5 is an adder, 6 is a divider, 7 is a direction extraction circuit, 8 is a direction memory, and 9 is a write control It is a circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa (and 2 others) Figure 1 Figure 2 Kanno 46 Procedural amendment (self-motivated June 9, 1988)

Claims (1)

[Claims] In a smoothing circuit that removes smudges such as blurring and breaks in lines of a linear image having a locally fixed direction, the linear image is divided into several local regions, and the divided local regions A smoothing method characterized by comprising: a direction extracting means for extracting the direction of a line for each direction; and a smoothing means for scanning and smoothing a local area in accordance with the direction of the line extracted by the direction extracting means. circuit.