JPH05314254A - Image processing method - Google Patents

Abstract

PURPOSE:To simply execute the print effect of images at real time by calculating the average luminance of a unit area and binarizing this average luminance value as a threshold value. CONSTITUTION:The average luminance value of 9 picture elements in the 3X3 convolution of an original picture stored in an input plane 1 is calculated and this is defined as the luminance value of the central picture element. This processing is performed so that all the picture elements of the original picture is made to the central picture element respectively, the average luminance value calculated as the result is stored in a threshold plane 2, and this is defined as a threshold value (b). An inter-image arithmetic circuit 3 calculates the threshold value (b) of the respective picture elements stored in the threshold plane 2 and a luminance value (a) of the respective picture elements of the original picture stored in the input plane 1 corresponding to this value (b) according to an expression Fix(a-b)=x and the arithmetic result is defined as (x). In the case of x=0, an output value is turned to '0', for example, and the picture elements of the original picture is converted to black, for example. In the case of xnot equal to 0, the output value is turned to '1', for example, and the picture elements of the original picture are turned to white, for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing for executing a print effect on an image.

[0002]

2. Description of the Related Art At present, a method for executing a print effect on an image has not been completed, and it is impossible to perform image processing for an effective print effect.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to easily realize a print effect for an image which has been impossible in the past.

[0004]

According to the present invention, image processing is performed by calculating the average luminance of a unit area and binarizing the average luminance value as a threshold value. According to the present invention, it is possible to execute a print effect of an image, which has been impossible in the past, in real time.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of image processing according to the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram according to the present invention. This circuit is composed of an input plane 1, a threshold plane 2, an inter-image calculation circuit 3, a look-up table 4 and an output plane 5. First, a method of determining the threshold value to be input to the threshold plane 2 will be described, but here, a 3 × 3 convolution is taken as an example.

First, the average luminance value of 9 pixels in the 3 × 3 convolution of the original screen A stored in the input plane 1 is calculated and used as the central pixel luminance value. Each pixel has 8-bit information, and the brightness value of each pixel is from 0 to 2
It is represented by 55 gradations. The above-described processing is performed so that all the pixels of the original screen A become the central pixels, and the average brightness value obtained as a result is stored in the threshold plane 2 and used as the threshold.

Next, in the inter-image calculation circuit 3, the threshold value b of each pixel of the screen B stored in the threshold plane 2 and the brightness value of each pixel of the original screen A stored in the input plane 1 corresponding to the threshold value b. a is calculated by the following formula, and the calculation result is set to x. Fix (ab) = x (1) Then, when x = 0, the output value is set to, for example, “0”,
The pixels of the original screen are converted into black, for example. On the contrary, if x = 0 is not satisfied, the output value is set to "1", and the pixels of the original screen are converted to white, for example. Conversely, the pixel may be converted to white when the output value is "0" and the pixel may be converted to black when the output value is "1".

For an image having a large variation in the luminance distribution, it is more effective to obtain the average luminance value in the 3 × 3 convolution and use the average luminance value as the threshold value as the threshold value several times. In many cases, you can get a nice print effect. For example, if this process is repeated 4 times,
It has the same effect as calculating the average luminance value in the convolution of x9 at once.

The average luminance value in the 9 × 9 convolution is slower in comparison with the average luminance value in the 3 × 3 convolution. That is, the rate of change of the threshold becomes slow. Therefore, in the part of the surface of the image where the brightness value is more uniform than the brightness value of the edge of the image, binarization based on the blunted threshold value of this change rate is the change rate of the 3x3 convolution. Compared to binarization based on the sharp threshold of
The digitization occurs (Fig. 2 (1)). Further, when binarization is performed based on the slower threshold of the convolution rate of 9 × 9, the edge portion of the image in which the difference in the luminance value changes abruptly is based on the sharp threshold of the convolution rate of 3 × 3. The edge becomes thicker as compared with performing binarization (FIG. 2 (2)). Therefore, the effect of roughening an image with a chisel is more likely to occur when binarization processing is performed by 9x9 convolution than when binarization processing is performed by 3x3 convolution.

[0011]

As described above, according to the present invention, it is possible to easily obtain a print effect on an image.

[Brief description of drawings]

FIG. 1 is a circuit diagram according to the present invention.

FIG. 2 is an example of a person image with a print effect.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toru Takahashi 2-22-2 Koishikawa, Bunkyo-ku, Tokyo Easel Co., Ltd.

Claims (2)

[Claims] 1. A certain convolution is set as a unit area, an average luminance value of the unit area is calculated, and the average luminance value is used as a threshold to determine the specific pixels in the unit area as 2
An image processing method characterized by digitizing. 2. The image processing method according to claim 1, wherein a 9 × 9 convolution is used as a unit area.