KR0123096B1 - Image encoder using contour - Google Patents

Abstract

The image coding device is capable of reducing a false contour generated when coding image is restored by using a contour. The image coding device using the contour includes: a contour constructing part for building the contour image of original image using contour information; a contour charging part for charging the contour image built in the contour constructing part using content information; a low-pass filter for filtering the decoded image outputted from the contour charging part; an edge detecting part for detecting the edge existing around the contour pixel for the decoded image outputted from the contour charging part; an AND gate for logically ANDing the output of the edge detecting part and the contour information to thereby generate a selection signal corresponding to the ANDed result; and a switching part for selectively outputting the image outputted from the contour charging part and the image outputted from the low-pass filter in accordance with the selection signal of the AND gate.

Description

Image coding device using contour

1 is a block diagram showing a conventional picture coding apparatus using contour lines.

2 is a block diagram showing a picture coding apparatus according to the present invention using an outline.

* Explanation of symbols for main parts of the drawings

11: contour construction unit 12: contour charging unit

13 edge detection unit 14 end gate

15 low pass filter 16 multiplexer

The present invention relates to a picture coding apparatus using contours, and more particularly, to a picture coding apparatus capable of reducing false contours generated when restoring an image encoded using the outlines.

In general, the performance of image encoding is evaluated according to the number of bits representing the image signal and the degree of distortion of the image reconstructed from the bits. One of the attempts to achieve a high compression ratio while the distortion of the image is not noticeably noticeable is region division image coding.

As is well known in the art, region division image coding separates an image into regions having similar pixel values, and then separates the contour representing the boundary and the content, which is information about the interior of the region. It is a method of encoding. However, since the contour and the content are completely different information, the encoding method is independent of each other.

Here, the image encoding using the contour is, as shown in FIG. 1, the contour construction unit 1 extracts the edge portion of the image using the contour information, and divides the image into several closed contours. In this case, the contour filling unit 2 is an encoding method for filling a closed outline by using content information. At this time, the content information indicates the texture of the image. However, when there is a change in the gray level, the content is often replaced by the average gray level in the closed outline because it forms another closed rust.

In this case, looking at the contour image (a) and the image (b) filled with the contour shown in FIG. As the gray level changes, it is divided into several segments. Subsequently, when the contour is filled, a false contour appears as shown in the image (b) in which the contour is filled.

Accordingly, the present invention is to solve the above-mentioned problems of the prior art, and if the pixel is a contour pixel, if there is an edge around it, the low pass filtering is not applied, and if the edge does not exist, the low pass filtering is applied by applying low pass filtering. SUMMARY OF THE INVENTION An object of the present invention is to provide an image encoding apparatus using contours capable of reducing the number of lines.

In order to achieve the above object, the present invention provides an outline construction unit for constructing an outline image of an original image using outline information, an outline charging unit for charging the outline image constructed in the outline construction unit using content information; A low pass filter for low pass filtering the decoded image output from the outline filling unit, an edge detector for detecting an edge present around the outline pixel for the decoded image output from the outline filling unit, and the edge An AND gate which inputs the output of the detector and the contour information and then performs a logical multiplication to generate a corresponding selection signal, an image output from the contour charger according to the selection signal output as the AND gate, and the low pass filter Contour consisting of switching section for selectively outputting the output image To provide a picture coding apparatus using the same.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an image encoding apparatus using contours according to a preferred embodiment of the present invention.

As shown in the figure, the image encoding apparatus of the present invention uses the contour construction unit 11 for constructing the contour image of the original image using the contour information, and the contour image constructed in the contour construction unit 11. For the contour filling unit 12 for charging using the content information, the low pass filter 15 for low pass filtering the decoded image output from the contour filling unit 12, and the decoded image output from the contour filling unit An edge detector 13 for detecting an edge existing around the contour pixel, an input gate of the edge detector 13 and the contour information, and then performing an AND operation to generate a selection signal corresponding to the AND gate ( 14) and selectively outputs the image output from the contour filling unit 12 and the image output from the low pass filter 15 in accordance with the selection signal output from the end gate 14. A switch, that is, a multiplexer (MUX) 15.

Next, an operation process of the present invention having the above configuration will be described in detail.

In FIG. 2, the outline constructing unit 11 and the outline filling unit 12 are the same components that perform substantially the same functions as the conventional coding apparatus shown in FIG. The description is omitted.

On the other hand, the edge detector 13 according to the present invention detects edges present in the periphery of the contour pixel for the decoded image output from the contour filling unit 12 based on the contour information. That is, the edge detector 13 generates a high level logic signal when no edge exists around the contour pixel.

Then, the above-described output of the edge detector 13 is input to one input terminal of the AND gate 14. In addition, contour information is input to the other input terminal of the AND gate. Accordingly, the AND gate 14 outputs a logic signal of high level to the multiplexer 16 when the condition that the contour information exists and the edge exists around it is satisfied.

On the other hand, the low pass filter 15 low pass filters the decoded image output from the contour filling unit 12 and outputs the result to the multiplexer 16.

In addition, the multiplexer 16 outputs the image output from the contour charging unit 12 and the image output from the low pass filter 15 according to the selection signal output from the AND gate 14, that is, a high or low level logic signal. Outputs an optional.

In other words, in the AND gate 14, when the high-level logic signal is scrambled, that is, when the pixel is a contour pixel and there is no edge around it, the image output from the low pass filter 15 is selected and output. When the low-level logic signal is output from the gate 14, that is, when an edge exists around the contour pixel, the image output from the contour charging unit 12 is selected and output.

As described above, according to the present invention, the low pass filtering is performed only when the corresponding pixel of the image is the contour pixel and there is an edge in the periphery thereof, thereby reducing false contours generated at the contour boundary due to the difference of gray levels. It can be effective.

Claims (1)

An outline construction unit for constructing a contour image of the original image using the contour information; Contour filling unit for charging the contour image constructed in the contour construction unit using the content information: Low pass filter for low pass filtering the decoded image output from the contour filling unit: To the decoded image output from the contour filling unit An edge detector for detecting edges present in the periphery of the contour pixels; An AND gate inputting the output of the edge detector and the contour information and performing a logical product to generate a selection signal corresponding thereto; And a switching unit for selectively outputting the image output from the contour charging unit and the image output from the low pass filter in accordance with the selection signal output from the AND gate.