Television – Bandwidth reduction system – Data rate reduction
Reexamination Certificate
1997-10-31
2001-03-06
Kelley, Chris S. (Department: 2713)
Television
Bandwidth reduction system
Data rate reduction
C358S296000
Reexamination Certificate
active
06198508
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of encoding data and an apparatus therefor, and more particularly, to a method of encoding picture data of a current line to be scanned using pixels of previous and next lines in a picture and an apparatus therefor.
2. Description of the Related Art
FIG. 1
is a block diagram showing the structure of a conventional shape encoder. As shown in
FIG. 1
, the shape of an input image is encoded as a bitstream through a shape encoder
11
and is displayed as an encoded bitstream
13
. The shape encoder
11
encodes the encoded bitstream
13
and a Shape Decoder
15
provides a reconstructed image.
In the conventional shape encoder, a greater number of encoded bits are required for resolution control and picture quality than in the case of performing encoding without such control. Accordingly, the encoding system becomes more complicated and becomes a burden on encoding. This is true of communication circumstances such as radio communication in which additional multiple functions such as functions of controlling resolution and picture quality, encoding which is resistant to transfer errors, and controlling a transfer rate, are employed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for encoding picture data in which pixel information of scanned lines in a binary image are encoded dependent upon comparison results between pixels of a previous scanning line and pixels of a current scanning line and between pixels of a next scanning line and pixels of the current scanning line.
To achieve the above object, there is provided a method for encoding an image according to the present invention, comprising the steps of determining whether pixels of a present scanning line in a predetermined frame of an image sequence should be encoded according to comparison results between pixels of a previous scanning line and pixels of a next scanning line and between pixel of a previous or next scanning line and pixel of the current scanning line, and encoding pixels of lines of the frame excluding pixels that are determined not to be encoded.
The pixels are determined to be different from each other by performing an exclusive-OR operation.
The step of determining the difference between pixels comprises the steps of dividing picture data into data of a scan interleaving pattern in a predetermined frame of an image sequence, and performing an exclusive-OR operation with respect to the respective pixels of the previous and next scanning lines of the current scanning line in said frame, wherein said step of encoding the image comprises the steps of generating previous and next scanning line information of said current scanning line, the resultant value (exclusive-OR information) of the exclusive-OR operation between the pixel of previous scan line and the pixel of next scan line corresponding to each pixel of said current scanning line, and the case-exception information of the current scanning line, which mean the pixel value of said current scanning line is different from the pixel value of previous or next scanning line, though the pixel values of the previous and next scanning lines of which are the same, and encoding the previous and next scanning line information of said generated current scanning line which forms a bitstream and encoding the pixel which is included in exclusive-OR information and case-exception information, and combining the same with said formed two bitstreams, to thereby form the complete bitstream.
The exclusive-OR operation is performed by replacing the next scanning line with the previous scanning line in the case that the current scanning line corresponds to the last scanning line in the frame.
The step of performing the exclusive-OR operation and the step of generating data are performed at least once with respect to the previous and next scanning lines by inputting the previous and next scanning line information of the current scanning line in order to process multi-level scanning lines.
Encoding of the pixel which is included in the exclusive-OR information of said step of forming a bitstream comprises the steps of obtaining the run-length of the pixels from successive exclusive-OR data which have the same value of current encoded pixel, and encoding said obtained run-length using a predetermined entropy encoding method.
The encoding of the exclusive-OR information in the step of forming the bitstream comprises the steps of obtaining a pixel context characteristic value determined according to a predetermined peripheral pixel value with respect to the pixels except for the pixel corresponding to the exclusive-OR information among the pixels of the scanning lines including the exclusive-OR information and the case-exception information among the scanning lines divided in the step of dividing the scanning line, mapping the obtained pixel context characteristic value by an established probability model value, and encoding the value mapped by the probability model value by a predetermined entropy encoding method.
The encoding of the case-exception information in the step of forming the bitstream comprises the steps of obtaining the pixel context characteristic value determined according to a predetermined pixel value with respect to each pixel except for the pixel corresponding to the exclusive-OR information among the pixels of the interleaved scanning lines including the exclusive-OR information and the case-exception information among the scanning lines divided in the step of dividing the interleaved scanning lines, one-dimensionally reconstructing the obtained pixel context characteristic value, extracting the pixel context characteristic value of the case-exception information pixel to be encoded, obtaining the number of appearances of the value equal to the extracted pixel context characteristic value between the case-exception information pixel to be encoded and the previously encoded case-exception information pixel, and encoding the said extracted pixel context characteristic value and the obtained number by a predetermined entropy encoding method.
Encoding of the case-exception information in said step of forming the bitstream comprises the steps of dividing pixels except for the pixel corresponding to said exclusive-OR information among the pixels of the interleaved scanning lines including said exclusive-OR information and said case-exception information among the interleaved scanning lines divided in said step of dividing the interleaved scanning lines in successive case-exception information segment unit, obtaining the pixel context characteristic value determined according to a predetermined peripheral pixel value with respect to the first pixel of said segment, one-dimensionally reconstructing said obtained pixel context characteristic value and the length of the segment which include said obtained pixel for each segment in a segment unit, obtaining the number of appearances of the value equal to said obtained pixel (the first pixel of each segment) context characteristic value between the case-exception information pixel to be encoded and the previously encoded case-exception information pixel, and encoding said obtained pixel context characteristic value, said obtained number and said obtained length of the segment which include said obtained pixel as first pixel by a predetermined entropy encoding method.
The method for encoding picture data further comprises a lossy coding step of selecting information to be coded or information not to be coded by the segment length and the step of measuring the number of generated information or the number of generated bits and determining the order in which the scan interleaving method is to be applied on the basis of number.
The scanning interleaving method can be applied to the picture data which is given after previous scanning interleaving method.
To achieve the above object, there is provided an apparatus for encoding picture data, comprising a scan analyser for analysing a current sca
Jang Euee-seon
Shin Jae-seob
Son Se-hoon
Burns Doane Swecker & Mathis L.L.P.
Kelley Chris S.
Samsung Electronics Co,. Ltd.
Vo Tung
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