JPH06303434A - Image processing method - Google Patents

Abstract

PURPOSE:To decrease the amount of transfer data of an image by dividing areas at every edge where pixels having relatively equal levels gather, area by area, and transferring difference data respectively. CONSTITUTION:An edge 1a which has a level higher than a specific value is extracted from an image to be transferred. Coordinates (X1, Y1) and (X2, Y2) which are at a specific distance L from the edge 1a in an X-axial and a Y-axial direction from both end points (Xmin, Ymin) and (Xmax, Ymax) including the edge 1a are found to find the rectangular divided area 2a having them as diagonal coordinates. Further, corrected divided areas matched with division lines obtained by sectioning Y1 and Y2 at a specific pitch in the Y-axial direction are found at every edge on a screen. The addresses of a quadrangle, reference pixel values, and difference values with the reference pixel values of the respective pixels are transferred to a receiving device at every area and reproduced on the reception side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method,
Particularly, it relates to an image processing method suitable for transferring a digital image.

[0002]

2. Description of the Related Art Conventionally, in a processing method for transferring a digital image, for example, data of about 8 bits per pixel is transferred for the entire screen. Therefore, in such a processing method, there is a problem in that the amount of image transfer data is extremely large, which requires a great deal of time for processing and transfer time.

[0003]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the main object of the present invention is to provide an image processing method capable of reducing the amount of image transfer data.

[0004]

According to the present invention, there is provided a process for extracting edges of an image to be transferred,
Generating a rectangular divided area surrounding the edge, transferring four corner coordinates of the divided area to a receiving side, and transferring a specific pixel value in the divided area as a reference pixel value to the receiving side. And a step of transferring the pixel difference of the other pixels in the divided area from the reference pixel value to the receiving side. It

[0005]

As described above, since it is estimated that the pixels having small differences in pixel value are gathered around the extracted edge of the image, a divided area surrounding the edge is formed, and the divided area is formed. By determining the reference pixel value in the pixel, the pixel value in the divided area can be transferred by transferring only the difference from the reference pixel value of each pixel, and the transfer data amount can be reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing edges in a digital image to be transferred to which the present invention is applied. Also, FIG.
The image transfer processing of the present invention will be described below with reference to the flowchart of FIG.

In step ST1, edges 1a to 1d composed of a portion exceeding a predetermined threshold value are extracted from the transferred image (FIG. 1). One of them, the edge 1a, is shown below. At step ST2, the respective minimum and maximum values Xmi of the edge 1a in the X-axis and Y-axis directions.
n, Xmax, Ymin, Ymax are detected. Regarding the edge 1a of the present embodiment, as shown in FIG. 3 which is an enlarged view of the edge 1a, the respective coordinates (Xmin, Ymin) and (Xmax, Ymax) of both end points of the edge 1a are the minimum.
Matches each coordinate of the maximum value.

In the next step ST3, as shown in FIG. 3, the minimum side X value which is decreased or increased by a predetermined value L in the direction away from the edge 1a in the X-axis and Y-axis directions from each end point of the edge 1a and The Y value, the maximum X value and the Y value are calculated. In this embodiment, as shown in FIG.
The minimum X and Y values are shown as X1 and Y1, and the maximum X and Y values are shown as X2 and Y2. Then, respective coordinates (X1, Y1) and (X2, Y2) which are diagonal coordinates when the rectangular divided area 2a surrounding the edge 1a is obtained.
Is required. In this way, the divided areas 2a to 2d are generated as shown in FIG.

In the next step ST4, for example Ya shown in FIG. 3 is divided in advance in the Y-axis direction at a predetermined pitch.
Y1 and Y2 are corrected so that the Y-axis direction range of the divided region is divided by each of the dividing lines Ya to Yf on each of the dividing lines of Yf to Yf (see FIG. 4). In the divided area 2a at the edge 1a of the present embodiment, Y1 =
Ya and Y2 = Yb. Thus, the coordinates (X1, Ya), (X1, Y) of the four corners of the corrected divided area 3a
b), (X2, Ya), (X2, Yb) are obtained.

In step ST5, for example, the minimum pixel value which is the minimum value of each pixel is detected in the corrected divided area 3a obtained as described above, and the minimum pixel value is stored as a reference pixel value. In ST6, the corrected divided area 3a
A pixel difference obtained by subtracting the reference pixel value from the pixel values of other pixels in the pixel is obtained for each pixel. In the next step ST7, the respective coordinates (X1, Ya), (X1,
Yb), (X2, Ya), (X2, Yb) are converted into address data. The reference pixel value, pixel difference, and address data are calculated by the pixel recognition device 4a, the area generation device 4b, and the arithmetic device 4c provided in the transmission device 4 as shown in FIG.

Then, in step ST8, each data of the reference pixel value, the pixel difference, and the address is transferred from the transmitter 4 to the receiver 5. The address is transferred to the storage order determining device 6 in the receiving device 4, the reference pixel value is transferred to the reference pixel value storage device 7, and the pixel difference is transferred to the adder 8.

In the receiving device 5, as shown in FIG. 6, a memory 9 is provided for writing the addresses transferred to the storage order determining device 6. The adder 8 adds the reference pixel value transferred to the reference pixel value storage device 7 and each pixel difference, and thus each pixel value of the transfer source is easily restored in the receiving device 5. . Then, the restored pixel value after the addition is written in the memory 9 in the storage location determined by the address transferred to the storage order determination device 6.

Hereinafter, for the other edges 1b to 1d,
The divided areas 2b to 2d and the corrected divided areas 3b to 3d are respectively obtained as described above, and the respective data are transferred. Regarding the other parts of the screen, the upper edge of the frame of the screen and the dividing lines Y in the Y-axis direction.
a to Yf, and in the X-axis direction, if there are correction divided areas 3a to 3d in their respective division ranges, divide them by the X-axis direction boundary line, and divide each rectangle in that way. The same processing is performed for each divided area and each data is transferred.

In this way, the image data of one screen can be transferred, and in the present embodiment, the portion other than the corrected divided areas 3a to 3d is, for example, a collection of relatively low-level pixels serving as a background. It is conceivable that the difference data of that portion can be made small, and each correction division area 3
Also in a to 3d, there is a high possibility that each region is a group of pixels of the same level, and the difference data can be suitably reduced for each region.

In the present embodiment, the method of obtaining the rectangular divided area surrounding the edge is such that the minimum side X value is decreased or increased by a predetermined value in the direction away from the edge in each of the X-axis and Y-axis directions from each end point of the edge. And Y value and the maximum X value and Y value were obtained, but the present invention is not limited to this. For example, the left and right points separated from each end point by a predetermined angle in the left-right direction with respect to the X-axis are determined, and either one of the left and right points is determined as a diagonal coordinate so as to surround the edge. Then, the rectangular divided area may be determined.

In this embodiment, the reference pixel value is set to the minimum pixel value, but it may be an intermediate value such as an average value. In that case, the receiving device considers whether the pixel difference is positive or negative. Then, if the pixel value is obtained, the same processing can be performed. Also,
In this embodiment, the divided area is divided into the respective division lines Y for the sake of ease of processing.
The correction is made according to a to Yf, but at that time, it is not limited to the correction of the dividing line in the direction of expanding in the Y-axis direction as shown in the embodiment, and it is adjusted to the closer dividing line. You may do it. Further, the processing may be performed by using the divided area obtained first as it is without using the dividing lines Ya to Yf. Further, according to the present invention, even when the shape of the edge is circular or arcuate, by detecting the points having the maximum and minimum values in the X-axis and Y-axis directions, respectively,
Similar to the above, it is possible to obtain a divided area that can surround the edge.

[0018]

As described above, according to the present invention, an edge of an image is detected, a divided area surrounding the edge is obtained, and for each divided area, an address indicating the area, a reference pixel value, and a reference value thereof. By transferring the pixel value and the pixel difference, the image transfer process can be performed with a small transfer data amount, and the processing speed can be increased and the image processing apparatus can be made compact.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing edges of a transfer image.

FIG. 2 is a flowchart showing an image transfer process.

FIG. 3 is an explanatory diagram for obtaining a divided area of a transfer image.

FIG. 4 is a diagram showing each divided area on one screen of a transfer image.

FIG. 5 is a diagram showing a modified divided area.

FIG. 6 is a block diagram showing a receiving device.

[Explanation of symbols]

 1a to 1d edge 2a to 2d divided area 3a to 3d modified divided area 4 transmitter 4a pixel recognizer 4b area generator 4c arithmetic unit 5 receiver 6 adder 7 reference pixel memory 8 storage order determiner 9 memory

Claims (1)

[Claims] 1. A process of extracting an edge of an image to be transferred, a process of generating a rectangular divided region surrounding the edge, a process of transferring four corner coordinates of the divided region to a receiving side, and the divided region. A step of transferring a specific pixel value within the divided area to the receiving side as a reference pixel value, and a step of transferring the pixel difference between the reference pixel value and the other pixel in the divided area to the receiving side. An image processing method comprising: