KR100209351B1 - Adaptive image transmission method using adaptive block truncation coding - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a progressive image transmission method using adaptive block truncation encoding, and more particularly, to a progressive image transmission method using adaptive block truncation encoding that can easily implement software or hardware due to a simple algorithm. The present invention aims to provide a new progressive image transmission method using adaptive block truncation coding with a simple algorithm and excellent data compression rate. To achieve the above object, the present invention provides an improved adaptive block truncation encoding method. Adaptive Block Truncation Coding (hereinafter referred to as ABTC) method and a new type of ABTC transmission parameter and transmission format are provided. The present invention provides a more improved HVS model. This is represented vertically as follows.

About T ₁ if k ₁ , = 0

T ₁ About T ₂ if k ₂ , = 0

For ≥ T ₂ if k ₃ , = 0

Where T ₁ = 50, T ₂ = 120, and k ₁ = -0.085 +40, k ₂ = 6, k ₃ = 0.075 +1.742

In the jnd model above Means each standard deviation, Means each mean. Using this equation, the method of having the improved ABTC applying the characteristics of the HVS to the expanded BTC is as follows. = , = X, if Back side = 0, i.e. = 0.

_{One h 1 h One One One h}

_{2 One 2 in 1 2 2 2 One}

The gradual transmission of the ABTC according to the present invention has all three passes. In the first pass, the degraded image is transmitted so that only the shape of the image can be recognized, and in the second pass, more detailed image information is reproduced through additional data transmission. In the third pass, the final image is played. Each of the second and third passes reproduces an image using data transmitted from the previous pass, so each pass has a hierarchical structure. In FIG. 5, the parameters to be transmitted for each pass are classified for the MP and MMSE in each pattern. The transmission format of the ABTC is largely composed of a header and a payload. The heading contains the information necessary for decoding. There are formats, mode-flags, pass-levels, vertical-sizes and horizontal-sizes.

Description

Progressive Image Transmission Method Using Adaptive Block Cutting Coding

1 is a diagram illustrating an extended block truncation encoding pattern.

2 shows an adaptive block truncation coding pattern.

3 is a diagram showing parameters of each pattern for adaptive block truncated encoding transmission.

4 illustrates an embodiment of adaptive block truncation encoding.

5 is a diagram showing parameters for gradual transmission for each path.

6 shows a transmission format of adaptive block truncation encoding.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a progressive image transmission method using adaptive block truncation coding, and more particularly, to a progressive image transmission method using adaptive block truncation encoding that can easily implement software or hardware due to a simple algorithm.

Hypertext Transfer Protocol (HTTP), an application layer protocol using TCP / IP, introduced in the 1990s, is being used with the World Wide Web (WWW). The Internet, which has been recognized as an existing international academic network due to the spread of the WWW, has become easy to use by many users and has become an opportunity to grow commercially. The remarkable growth of the Internet has made it possible to build a basic infrastructure for the high speed of the national network.

International standardization study on compression method for storing and transmitting huge amount of video signal, which is the core element in multimedia service, starts with JBIG, which defines the compression method of binary image for facsimile, JPEG, ISDN It has led to H.261, which is applied to video phone for mobile phones, and MPEG-2 for MPEG-1 and high definition TV signals for digital storage media.

However, despite the development of the technology for the compression method, the development of the peripheral device for the terminal is still insufficient, so the recognition of the multimedia has not been widely spread. Today's Internet, which provides multimedia services via computer or data communication, will be in the spotlight according to the evolutionary strategy, but it is not enough to accommodate wide bandwidth video data, and the demand is gradually increasing. Therefore, there are many limitations in providing a full-fledged multimedia service.

Currently, the format of the video provided on the Internet is very diverse. Among these, GIF (Graphics Interchange Format) and JPEG are mainly used as still image formats. The importance of the still image is also provided in the still image information itself, but the progressive image transmission is possible to facilitate the search of the image database visually in the provision of the moving image. However, JPEG's progressive transmission method has a very complicated problem, and interlaced-GIF which shuffles and transmits each line data among GIFs is hardly regarded as a progressive method.

Accordingly, an object of the present invention is to provide a new progressive image transmission method using adaptive block truncation coding with simple algorithm and excellent data compression rate.

In order to achieve the above object, the present invention is characterized by providing an improved Adaptive Block Truncation Coding (hereinafter referred to as ABTC) method and a new type of ABTC transmission parameter and transmission format.

The above and other objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Adaptive block-cutting coding has been proposed as a method to solve the defects caused by Discrete Cosine Transform (DCT) in the corners of an image in digital video coding such as computer graphics or animation.

ABTC, a pure intra mode unconverted video coding method without reference video, shows excellent performance not only in video but also in still images.

Conventional block truncation coding (BTC) reproduces a block of 4x4 pixels at two levels, whereas ABTC obtains four reproduction level values, and then a human visual system (hereinafter referred to as BTC). A method of applying a just noticeable difference (hereinafter referred to as jnd) of the HVS. The number of levels played varies from 1 to 4 depending on the characteristics.

In order to expand the BTC for reproducing blocks at four levels, the input pixels should be classified into four sets as follows.

Here, X _h means an average of pixels larger than the pixel average X of the input block, and X ₁ means an average of pixels smaller than X.

In the above formula (1), the number of pixels of the set A, B, C, and D is assumed to be p, q, s and r, respectively.

The method of determining the reproduction level for the pixels classified from Equation (1) includes the same first and second moment preserving method as conventional BTC and MMSE (Minimizing Mean Squared) which minimizes the mean square error. Error) method. The regeneration level is changed according to each method, which is shown in equations (2) and (3), respectively.

In equation (2) _h , ₁ denotes the standard deviation of pixels greater than or equal to X and pixels less than X, respectively, and r ₁ , r ₂ , r _3, and r ₄ in Equations (2) and (3) represent the reproduction levels of each set. The reproduction values in the case of MP can be obtained by the same method as the conventional BTC, and the reproduction values in the case of MMSE are determined by the average value of the pixels corresponding to each set.

The expansion result of BTC obtained from the above is divided into five patterns as shown in FIG. 1 according to the statistical characteristics of each sub-image.

In FIG. 1, the first pattern is a case where the pixels in the block have a very large correlation. In the second pattern, pixels larger than X and pixels smaller than X each have a large correlation. The third pattern is a case in which pixels smaller than X are relatively widely distributed while pixels larger than X have a large correlation. The fourth pattern is the case opposite to the third pattern. The fifth pattern corresponds to the case where the pixels have a wide distribution.

The data rate of this extended BTC is X _h , X _l , _h and _Since 8 bits are required for _l and 32 bits are required for bit plane transmission, the result is 4bpp as in the case of MP. In the case of MMSE, 8 bits are required for X _hh , X _hl , X _lh, and X _ll , respectively, and 32 bits are required for bitplane transmission. This is twice the rate of conventional BTC. The high data rate can be reduced by using jnd of HVS. However, the HVS model used in the conventional adaptive block truncation encoding has a disadvantage in that the blocking phenomenon occurring in the existing BTC is partially shown.

Therefore, the present invention proposes a solution accordingly.

Each of X, X _h and X _l is called background brightness I and the playback level is I + I is the jnd identifiable by HVS I will have a constant value. Therefore, Weber's law states that it is more sensitive to changes in intensity in dark areas than in bright areas.

The present invention provides a more improved HVS model. This is expressed as a formula as follows.

Where T ₁ = 50, T ₂ = 120, and k ₁ = -0.085 +40, k ₂ = 6, k ₃ = 0.075 +1.742

In the jnd model of equation (4) Means each standard deviation, Means each mean. Using this equation, the method of having the improved ABTC applying the characteristics of the HVS to the expanded BTC is as follows. = , = X, if Back side = 0, i.e. = 0.

_{One h 1 h One One One h}

_{2 One 2 in 1 2 2 2 One}

FIG. 2 shows the occurrence pattern of ABTC obtained by applying j.n.d. of HVS of Equation (4) to an extended BTC using the above method. In the ABTC transmission, the necessary parameters are different for each pattern, which is shown in FIG.

4 is a case where the MMSE-ABTC coding result pattern of one block of girl 1, which is frequently used as a test image, is 4, and in FIG. 2, a pixel having a value smaller than X is reproduced as X ₁ , and The pixel is reproduced with two values. Therefore, as shown in FIG. 4, all of the lower bit planes (BPLs) should be transmitted, but the transmission of the higher bit planes (BPHs) can be restored only by transmitting bit plane information of pixels having a BPL value of 1. Therefore, BPH information marked with X does not need to be transmitted. In the case of the third pattern, transmission can be performed using the same principle as described above.

Hereinafter, gradual image transmission using the ABTC will be described.

The gradual transmission of the ABTC according to the present invention has all three passes. In the first pass, the degraded image is transmitted so that only the shape of the image can be recognized, and in the second pass, more detailed image information is reproduced through additional data transmission.

In the third pass, the final image is played. Each of the second and third passes reproduces an image using data transmitted from the previous pass, so each pass has a hierarchical structure. In FIG. 5, the parameters to be transmitted for each pass are classified for the MP and MMSE in each pattern.

Referring to the case of MP-ABTC, the transmission of parameters for each path for each pattern of FIG. 5 is as follows.

The first pattern is a case in which one block is reproduced with only an average value, and only X can be reproduced. No further information is needed in the second and third passes.

The second pattern is a block that is reproduced at two levels like the existing BTC. In the second pass, only the X is sent. And BPL information is transmitted.

The third pattern is a case where an area of a pixel smaller than X which is an average of blocks is reproduced at two levels. Therefore, X _h is required in the first pass, and the entire block is reproduced with this value. In the second pass, X _l and BPL information are transmitted. At this time, only the pixel whose value of BPL is 0 is changed to X _l . In the third pass _{l l l}

The fourth pattern is reproduced in a case where it is contrasted with the third pattern or through a process similar to the third pattern.

In the fifth pattern, blocks are reproduced with the entire average value only in the first pass, two levels are reproduced in the second pass, and finally, four levels are reproduced in the third pass. In FIG. 5, the number in parentheses indicates the number of bits required for transmission, and V means the number of variable bits.

6 is a transmission format. The transport format of the ABTC is largely composed of a header payload. The heading contains the information necessary for decoding. There are formats, mode-flags, pass-levels, vertical-sizes and horizontal-sizes.

The format means a color signal format of the input image (8 bits).

1: 420 YIQ format

2: 422 YIQ format

3: 444 YIQ format

4: RGB format

5: GRAY format

Other not defined

The mode-display tells how to calculate the playback level (4 bits).

0: MP ABTC

1: MMSE ABTC

Other not defined

Pass-pevel means the number of passes to decode (4 bits). Currently it is fixed at 3.

Vertical-size refers to the vertical size of the image (32 bits).

The horizontal-size refers to the horizontal size of the image (32 bits).

In the payload, the color signal component of the block is transmitted for each pass. The values transmitted at this time are as shown in FIG. Here, the transmission of the block parameter according to the color signal format is the same as that of the macro block defined in MPEG-2.

As described above, the present invention provides a gradual transmission algorithm of still images using adaptive block truncation coding. The method of the present invention is simpler than JPEG in terms of algorithm when comparing performance with conventional JPEG, so that software and hardware can be easily implemented. In addition, the present invention can efficiently provide image information even in an independent system, and in particular, it can be very useful for transmitting still images or searching a video database in the conventional Internet.

Preferred embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, additions, etc. within the spirit and scope of the present invention and such modifications should be regarded as belonging to the following claims. .

Claims (5)

A progressive image transmission method using adaptive block truncation encoding, wherein the noticeable difference model of the human visual system satisfies the following equation. About T ₁ if k ₁ , = 0 T ₁ About T ₂ if k ₂ , = 0 About T ₂ if k ₃ , = 0 ( Is the standard deviation of the pixels, Is the mean, T ₁ = 50, T ₂ = 120, k ₁ = -0.085 +40, k ₂ = 6, k ₃ = 0.075 +1.742) In the progressive image transmission method using adaptive block encoding, adaptive block truncation encoding satisfies the following equation. Back side = 0 _{h h h l l l} ( : Standard deviation of each pixel, the standard deviation of the pixels with a value greater than the average of the _h pixels, _l : standard deviation of pixels having a value smaller than the average of pixels, : Mean value of each pixel, _h : average value of pixels having a value larger than the average value of the pixels, _l : average value of pixels having a value smaller than the average value of the pixels) In the progressive video transmission method using adaptive block truncation encoding, three passes are used for transmission, and the parameter assignment for each pass is X in the first pass, no pass in the second pass, and the third pass in the case of the first pattern. In the second pattern, MP is X in the first pass, and in the second pass, And BPL, MMSE assigns X _{h to} the first pass, X _l and BPL information to the second pass, and no information is assigned to both MP and MMSE to the third pass. X _h , X _l and BPL in the second pass, _l and BPH, MMSE is X _h in the first pass, X _ll and BPL in the second pass, and X _{hl in} the third pass. And BPH, for the fourth pattern, MP is X _h in the first pass, X _l and BPL in the second pass, and _h and BPH, MMSE assigns X _{hh to} the first pass, X _hl and BPL to the second pass, X _lh and BPH to the third pass, and for the fifth pattern, MP is X _h in the first pass. For the second pass, X _l and BPL, for the third pass, _{h l hh lh hl} In the progressive video transmission method using adaptive block truncation encoding, the transmission format is composed of a header and a payload for transmitting color signal components for each path. Video transmission method. The format of claim 4, wherein the heading comprises a format, a mode-flag, a pass-level, a vertical-size, and a horizontal-size, and a format representing a color signal format of an input image includes a 420 YIQ format and a 422 YIQ. Format, 444 YIQ format, RGB format, and GRAY format, where the mode-indication indicating how to calculate the playback level indicates 0 for MP ABTC, 1 for MMSE ABTC, and pass-level for the number of passes to decode. And a vertical-size means a vertical size of an image, and a horizontal-size indicates a horizontal size of an image.