JP2910295B2 - Contour information extraction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outline information extracting apparatus for extracting a graphic outline from binary raster data obtained by quantization with an image scanner or the like. It is used for devices, line graphic vector conversion devices, and the like.

[0002]

2. Description of the Related Art Conventionally, an apparatus for extracting a contour of a figure by contour tracing processing has only one contour tracing means, or performs contour extraction from a divided image obtained by spatially dividing an image by a parallel processing device. Was.

[0003]

However, in an apparatus having only one contour tracing means, there is no other way to increase the processing speed except by increasing the operating frequency.
There is a problem that manufacturing costs increase. Further, since the achievable processing speed depends on the achievable operating frequency, it may be difficult to obtain a necessary processing time.
Further, in a device that extracts a contour from a divided image, there is a problem that a figure at a boundary portion of the space division is separated and detected.

[0004] It is an object of the present invention to provide a contour extracting apparatus which can obtain a high processing speed without detecting one object in a form divided into a plurality of parts as occurred in a conventional parallel processing apparatus. .

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided an outline information extracting apparatus for extracting outline information from a binary image, comprising: first image storage means for storing a binary image; An image transfer unit that simultaneously transfers the image data to a plurality of second image storage units described below, and a plurality of contour extraction devices;
Each of the contour extraction devices includes a second image storage unit for storing an image transferred through the image transfer unit, and a raster scan of a partial rectangular area of the image stored in the second image storage unit. A tracking start point detecting means for detecting a coordinate value of a boundary pixel whose pixel value changes from 0 to 1 and which does not have a tracked mark, and uses this pixel as a tracking start point; A contour tracking means for performing a process of successively performing a process of adding a tracked mark to this pixel, outputting a coordinate value, detecting a boundary pixel adjacent to the pixel, and setting the pixel as a next pixel of interest; The coordinate value of the point of interest output from the contour tracking means is input, and when the point of interest moves beyond the upper or left boundary of the rectangular area in the image, a data rejection signal is transmitted to the contour tracking means to trace the contour. Cancel the processing and A region boundary detection means for rejecting an output contour information and is characterized by comprising a contour information storage means for storing contour information output from said contour tracing means.

[0006]

The operation of the present invention will be described with reference to the drawings.

FIG. 2 shows a binary image. One square surrounded by a dotted line in the figure corresponds to one pixel. An unfilled square indicates a background having a pixel value of 0, and a square filled with black and diagonal lines indicates an object having a pixel value of 1.
Among the pixels indicating the object, the boundary pixels that form the boundary with the background are indicated by oblique lines. Hereinafter, a method of extracting the contour of this image using the four contour extracting devices (1), (2), (3), and (4) will be described.

Each contour extraction device is assumed to include a tracking start point detecting means for detecting a boundary pixel at which contour tracking is started, and a contour tracking means for sequentially tracking the boundary pixel. The tracking start point is detected by a raster scan (the x direction is a main scanning direction) within a specified rectangular raster scan area.
The contour tracking is performed in the entire image area. In the processing flow, it is assumed that first, a boundary pixel serving as a start point is detected by the tracking start point detecting means, and then contour tracking is performed by the contour tracking means. The contour tracking ends when the start point is detected twice, but the tracking start point detection process is restarted again.

Now, the same image is input to the four contour extraction devices. The raster scan area is determined so as to cover all the images without overlap by the four devices. In this example, as shown in FIG. Device (1): Region I Device (2): Region II Device (3): Region III, Device (4): Region IV Assuming that the size of the input image is 2L × 2M, the range of each region is as follows. is there. Area I: {x, y | 0 ≦ x <L, 0 ≦ y <M} Area II: {x, y | L ≦ x <2L, 0 ≦ y <M} (1) Area III: {x, y | 0 ≦ x <L, M ≦ y <2M} Region IV: {x, y | L ≦ x <2L, M ≦ y <2M} During contour tracing, a boundary exceeding the lower limit of the x or y coordinate of the raster scan area If a pixel is detected, the contour data being tracked is rejected. As a result, if the outputs of all the devices are referred to after the completion of all the processes, all the outline information is obtained without duplication. In this case, each contour tracking means rejects data when a pixel satisfying the following rejection condition is accessed during contour tracking. Contour extraction device (1): x <0 or y <0 Contour extraction device (2): x <L or y <0 (2) Contour extraction device (3): x <0 or y <M Contour extraction device (4 ): X <Lory <M Referring to FIG. 2, the contour extraction device (1) first detects contour data from the boundary pixel A first detected by raster scan by contour tracing. Since the pixel satisfying the rejection condition (2) is not accessed, the data is output as it is. The contour extraction device (2) first detects the boundary pixel B, but satisfies the rejection condition (2) when accessing the pixel C by contour tracing. Therefore, this contour data is rejected.
The contour extraction device (3) first detects the boundary pixel D,
By detecting the pixel E, the rejection condition expression (2) is satisfied, and the data is rejected. Similarly, the contour extraction device (4) detects the boundary pixel F, but rejects the data by detecting the pixel E. After all, the figure in the image of FIG.
It is extracted only by the contour extraction device (1) and does not cause duplication.

[0010]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. This contour information extraction device includes an image storage unit 1 and an image transfer unit 2
And four contour extraction devices 100. Each contour extraction device 100 includes an image storage means 3, a tracking start point detection means 4, a contour tracking means 5, an area boundary detection means 6,
And an outline information storage means 7.

The image storage means 1 is constituted by a memory element. When the size of the binary image to be processed is 2L × 2M [pixels], the memory capacity requires 4 LM bits.

The image transfer means 2 has a function of reading out the image data stored in the image storage means 1 and transferring it to the image storage means 3 of each contour extraction device 100, and has an address for generating an address of each pixel of the image. It comprises a generation circuit, a data read circuit for reading out the memory address or image data generated by the address generation circuit, a data transfer circuit for transferring the read data to the image storage means 3 via a data bus, and the like. The image transfer means 2 starts data transfer immediately after a start signal is input from the outside.

The image storage means 3 of the contour extraction device 100
Like the image storage means 1, it is constituted by a memory element, but has a capacity of 2 bits per pixel.

The tracking start point detecting means 4 includes the image storing means 3
, An address generation circuit for reading the pixel values stored in the raster scan order, a data read circuit for reading the value of the pixel of interest and its eight neighboring pixels, and a tracking start point determination for determining whether or not the tracking start point Circuit. FIG. 3 shows the tracking start point determination circuit. In FIG. 3, p _t values of the target pixel t is detected in the raster scanning, p ₀ ~p ₇ is the value of neighboring pixels of the target image element. Further, _pt2 is the value of the label of the pixel t, and takes a value of 1 when _pt is a tracked boundary pixel, and takes a value of 0 when pt is an untracked pixel. Note that the label value is written by the contour tracking means 5 described below.

The tracking start point detecting means 4 is executed immediately after the image transfer processing of the image transfer means 2 is completed. When the tracking start point is detected, the operation is temporarily stopped while holding the address of the pixel of interest, and the contour tracking means 5 is activated. After the operation of the contour tracing means 5 is completed, an address next to the held address is set again, and the operation starts. When all the raster scans have been completed by the tracking start point detection means 4, all the operations of the contour information extraction device are completed.

The contour tracing means 5 accesses the data of the image storage means 3, an address generation circuit, a circuit for reading out the value of a pixel of interest and eight pixels in the vicinity thereof, and writes a tracked label at a tracked boundary pixel position. A circuit, a boundary pixel detection circuit for detecting an adjacent boundary pixel from the target boundary pixel, a circuit for outputting a direction from the target pixel to the adjacent boundary pixel as a direction code shown in FIG. 4, a coordinate of a tracking start point A circuit for outputting a value;

FIG. 5 shows a circuit for outputting a direction code. Although the output of the direction code is output to the outside in a detection unit of one pixel, when a data rejection signal of the boundary pixel detection circuit is received, the function of returning the address counter to the head address value of the object being tracked is provided.

As described in the operation of the present invention, the area boundary detecting means 6 converts the coordinate value indicating the preset lower limit of the raster scan area and the coordinate value of the pixel of interest output from the contour tracking means 5 into the contour. During the tracing process, a function is provided for outputting a data rejection signal to the contour tracing means 5 when the comparison is made by the comparator circuit and the rejection condition (2) is satisfied. The area boundary detection means 6 is activated by the tracking start point detection means 4.

The contour information storage means 7 is constituted by a memory element having a function of storing coordinate value data output from the contour tracking means 5.

[0021]

According to the present invention, it is possible to provide a contour information extracting apparatus for performing a high-speed contour extracting process using a plurality of contour extracting means having similar functions.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is a diagram showing a tracking start point determination circuit.

FIG. 4 is a diagram showing a direction code.

FIG. 5 is a diagram showing a circuit for outputting a direction code.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image storage means 2 image transfer means 3 image storage means 4 tracking start point detection means 5 contour tracking means 6 area boundary detection means 7 contour information storage means 100 contour extraction device

Claims (1)

(57) [Claims] 1. An outline information extracting apparatus for extracting outline information from a binary image, comprising: a first image storage means for storing a binary image; and a plurality of second image data stored in the image storage means.
Image transfer means for simultaneously transferring the image data to the image storage means, and a plurality of contour extraction devices, each of which includes a second image storage means for storing an image transferred through the image transfer means, A raster scan is performed on a partial rectangular area of the image stored in the second image storage means to detect a coordinate value of a boundary pixel where a pixel value changes from 0 to 1 and a tracked mark is not attached, A tracking start point detecting unit that uses this pixel as a tracking start point; a tracking target point that is the first target pixel; a tracked mark is attached to this pixel to output a coordinate value; A contour tracking unit that sequentially performs processing of detecting a pixel and setting it as a next pixel of interest, and a coordinate value of a point of interest output from the contour tracking unit is input, and the point of interest is located above or above the rectangular area in the image. Moved past left edge A region rejection means for transmitting a data rejection signal to the contour tracking means to stop the contour tracking processing and rejecting the already output contour information, and a contour information storage means for storing the contour information output from the contour tracking means. An outline information extraction device characterized by comprising: