JPH04326671A - Picture encoding device - Google Patents

Abstract

PURPOSE:To perform efficient encoding with a high picture quality by using the continuity of an outline to extract and separate the line drawing part of a picture. CONSTITUTION:An inputted picture signal is divided into NXM picture element blocks by an NXM-picture element memory 201, and edge parts of picture element blocks are detected by an edge detecting part 202 and are stored in an edge memory 203. A close loop part of edge parts is detected by a continuity detecting part 204, and the line drawing part is extracted by a line drawing part extracting part 205, and bit map information and gradation information of its pattern are outputted, and thereby, compression adapted to each signal is performed, and efficient encoding is possible with a high picture quality.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding device capable of compressing image information.

0002

2. Description of the Related Art Conventionally, an image encoding apparatus simply compresses and encodes input image signals.

0003

[Problems to be Solved by the Invention] However, the above conventional example has the following drawbacks.

(1) When compressing and encoding an input image consisting of (characters, line drawings) and (natural images), if highly efficient encoding is performed on (natural images), (characters, line drawings) and (natural images) , line drawing)
Significant image deterioration occurs.

(2) Furthermore, if an encoding method that does not cause deterioration of (characters, line drawings) is used, highly efficient encoding of (natural images) cannot be performed.

[0006] From (1) and (2) above, it was impossible to encode characters (characters, line drawings) and (natural images) with high efficiency using the same encoding method because their image properties were different from each other. .

The present invention has been made to solve the above problems, and by extracting and separating the line drawing part of an image using the continuity of the edge part, it is possible to perform high-quality and highly efficient encoding. The purpose of the present invention is to provide an image encoding device that enables image encoding.

[0008]

Means for Solving the Problems and Operations In order to achieve the above object, an image encoding device of the present invention has the following configuration. That is, an image encoding device that encodes image information includes a continuity detection means for detecting continuity of edge portions of the image information, and a line drawing portion is extracted based on the information detected by the continuity detection means. and a replacement means that replaces the line drawing extracted by the line drawing extracting means with a predetermined value.

[0009] Also preferably, the continuity detection means comprises:
It is characterized by detecting continuity of edge portions by recording edge information in a stack memory.

More preferably, the line drawing portion extraction means comprises:
A feature of this method is that the line drawing portion is extracted based on the address information of the edge portion recorded in the stack memory.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of an image encoding apparatus in an embodiment. As shown in the figure, an image signal input to an encoding unit 101 is extracted and separated into a bitmap signal 103 and a gradation signal 104 for characters and line drawings by a signal separation unit 111, the details of which will be described later. . Furthermore, for a natural image of an image signal, a natural image signal 105 in which characters and line drawing portions are replaced with predetermined values.
is output, JPEG (Joint Photogra
phic Expert Group) ADCT (A
dvanced Discrete CosineTr
high efficiency data compression is performed at 112 (transform) 112. After that, the signal decoded by IADCT 121, the above-mentioned bitmap signal 103 and grayscale signal 104
is input to the combining section 122, and is combined with the original image signal and output.

Next, the detailed configuration of the signal separation section 111 described above will be explained with reference to the block diagram shown in FIG. First, the input image signal is stored in the N×M pixel memory 201.
It is divided into ×M pixel blocks. Here, for the sake of simplicity, an 8×8 block will be explained. Next, an edge portion of the pixel block is detected by a known two-dimensional edge detection unit 202 and stored in an edge memory 203. The continuity detection unit 204 detects the closed loop part of the edge part, and the line drawing part extraction unit 205 extracts the closed loop pattern and outputs it as bitmap information and gradation information of the pattern. Also, natural image information is N×M
From the signals from the pixel memory 201, appropriate values are substituted and output so as to facilitate high-efficiency data compression, except for the above-mentioned closed loop pattern.

The algorithm of the continuity detecting section 204 described above will be explained below.

FIG. 3 is a diagram showing addresses for 8×8 blocks. FIG. 4A shows an example of an image pattern input to the N×M pixel memory 201, and FIG. 4B shows an edge portion detected by the edge detection unit 202 and stored in the edge memory 203. FIG. 3 is a diagram showing stored edge patterns. Then, the memory 203 shown in FIG. 5B is scanned sequentially from left to right from the top, and the presence or absence of data is checked. When edge part 1 is detected, the address is stored in the stack memory S1 shown in FIG. Record. here,
If any address adjacent to the address (i, j) of the pixel of interest is recorded in the stack, it is determined that the pixel of interest is continuous with the pixel at the address recorded in the stack. For example, the address of edge portion 2 or 3 is recorded in stack S1 because it is adjacent to the address recorded on stack S1. However, since the address of edge section 4 is not adjacent to the address of edge section 3 on stack S1, new stack S
2 is created and recorded there. In this way, the continuity of the edge portions is determined, and it can be determined that the top addresses (edge portions 12) of the stacks S1 and S2 are the same and are adjacent. Further, it can be seen that the stacks S1 and S2 are adjacent to each other from the lowest addresses (edge part 1, edge part 4).

Therefore, it is found that this pattern is a closed loop, and this is recognized as a line drawing portion, and a bit pattern is generated. Furthermore, for the gradation signal, one piece of data within this closed loop is taken out as a representative value.

In the case of the image pattern (a) shown in FIG. 6, the pattern extends over the edge of the block. In this case, it is processed similarly by the algorithm described above,
As a result, stacks S1 to S4 shown in FIG. 7 are respectively created. Here, the adjacency relationship can be identified from the addresses (edge part 8) recorded at the top of stacks S1 and S3, and the adjacency relationship can be identified from the addresses (edge part 14) recorded at the top of stacks S2 and S4. Adjacency relationships can be identified. Then, when we examine the addresses recorded at the bottom of stacks S1 and S2, we see that the y components of the addresses of edge part 1 and edge part 2 are zero, and these are the edges of the block, so these are considered to be adjacent. . Similarly, since the x component of the address of edge portion 7 and edge portion 12 is zero, they are considered to be adjacent. Therefore, a closed loop is cut out from FIG. 7, and a bit pattern and grayscale signal are generated as in the case described above.

As explained above, according to this embodiment,
By extracting the line drawing part using the continuity of the contour (edge part), the image signal can be converted into a bit map signal, gradation signal,
By separating the natural image signals and applying appropriate compression to each signal, highly efficient encoding is possible while maintaining high image quality. In particular, since the line drawing portion is detected using the continuity of the edge portion, it can be detected accurately.

[0019]

[Other Embodiments] Next, other embodiments according to the present invention will be described below with reference to the drawings.

FIG. 8 is a block diagram showing the detailed configuration of the signal separation section in another embodiment. Note that blocks having the same functions as those in FIG. 2 referred to in the above-described embodiment are designated by the same reference numerals, and description thereof will be omitted here.

As shown in the figure, in this embodiment, a comparator 20 is provided between the edge detection section 202 and the edge memory 203.
7, and is configured to compare the signal from the edge detection unit 202 with a certain set threshold value, and record only signals larger than the threshold value in the edge memory 203. Here, the threshold value is set to a value at which disturbing noise is below the detection limit when the natural image signal is compressed. This makes it possible to reduce the stack memory in the line drawing portion extracting unit 205 and to perform encoding with higher efficiency.

The present invention may be applied to a system composed of a plurality of devices such as a reader, an interface, and a printer, or to an apparatus composed of a single device such as a copying machine. It goes without saying that the present invention can also be applied to a case where the present invention is achieved by supplying a program stored in a floppy disk, an ID card, etc. to a system or device.

[0023]

[Effects of the Invention] As explained above, according to the present invention,
By extracting and separating the line drawing portion of an image using the continuity of contours, high-quality and highly efficient encoding becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the configuration of an image encoding device in this embodiment.

FIG. 2 is a block diagram showing a detailed configuration of a signal separation section in this embodiment.

FIG. 3 is a diagram showing address assignment of an 8×8 pixel block.

FIG. 4 is a diagram showing an image pattern and a detected edge pattern.

FIG. 5 is a diagram showing a state recorded in a stack memory.

FIG. 6 is a diagram showing an image pattern and a detected edge pattern.

FIG. 7 is a diagram showing a state recorded in a stack memory.

FIG. 8 is a block diagram showing a detailed configuration of a signal separation section in another embodiment.

Claims (3)

[Claims] 1. An image encoding device for encoding image information, comprising: continuity detection means for detecting continuity of edge portions of the image information; and a line drawing based on the information detected by the continuity detection means. 1. An image encoding device comprising: a line drawing part extracting means for extracting a line drawing part; and a replacing means for replacing a value of the line drawing part extracted by the line drawing part extracting means with a predetermined value. 2. The image encoding device according to claim 1, wherein the continuity detection means detects continuity of edge portions by recording edge information in a stack memory. 3. The image encoding apparatus according to claim 2, wherein the line drawing portion extracting means extracts the line drawing portion based on address information of an edge portion recorded in a stack memory.