US6415060B1
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Lossless transform coding system having compatibility with lossy coding
Assignee: NEC Corp
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Filing: 2000-10-20
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Granted: 2002-07-02
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Expires: 2020-10-20
Abstract
Abstract A reversible eight-element DCT providing values near to transform values of the original DCT. In a 4×4 matrix, coefficients (X 1 , X 7 , X 3 , X 5 ) are separated into (X 1 , X 7 ) and (X 3 , X 5 . If (X 1 , X 7 ) are determined, then (X 3 , X 5 ) values are limited. (X 1 , X 7 ) are linearly quantized with steps k 1 , k 7 to obtain quantization values (Xq 1 , Xq 7 ). (X 3 , X 5 ) are divided into global and local signals. The global signals are linearly quantized with steps L 3 , L 5 , and local signals are determined using a table. The quantization values of (X 3 , X 5 ) are added to obtain quantization values (Xq 3 , Xq 5 ). The reversible 4×4 matrix and conventional 2×2 matrices are combined to construct a reversible eight-element DCT.
Inventors
- 👤 Ryoma Oami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:42
CPC Classifications
G; G06; G06T; G06T9/00; G06T9/007
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
614 words
A reversible transform coding system which includes a reversible transformer which inversely transforms quantization values (Xq 1 Xq 7 , Xq 3 , Xq 5 ) into an integer four-element vector (u 4 , u 5 , u 6 , u 7 ), said reversible transformer including: means for calculating global signals (p 3 , p 5 ) and local quantization values (sq 3 , sq 5 ) from the quantization values (Xq 3 , Xq 5 ); means for determining quantization residuals (r 1 , r 7 ) from the local quantization values (sq 3 , sq 5 ) based on a third numeric table, means for multiplying the quantization values (Xq 1 , Xq 7 ) by natural numbers k 1 , k 7 and adding the quantization residuals (r 1 , r 7 ) to the products to obtain transform coefficients (X 1 , X 7 ), respectively; means for determining representative elements (s 3 , s 5 ) from the transform coefficients X 1 , X 7 based on a fourth numeric table; means for adding the representative elements (s 3 , s 5 ) to the global signals (p 3 , p 5 ) to obtain transform coefficients (X 3 , X 5 ); and means for linearly transforming the transform coefficients (X 1 , X 7 , X 3 , X 5 ) with an inverse matrix to a matrix [ a 1 a 7 a 3 a 5 a 7 - a 1 - a 5 a 3 a 3 - a 5 - a 7 - a 1 a 5 a 3 - a 1 a 7 ] - 1 to obtain the integer four-element vector (u 4 , u 5 , u 6 , u 7 ), wherein said means for calculating global signals (p 3 , p 5 ) and local quantization values (sq 3 , sq 5 ) from the quantization values (Xq 3 , Xq 5 ) includes: means for calculating global signal candidates (p 3 (0) , p 5 (0) ) from the quantization values (Xq 3 , Xq 5 ) based on two dimensional division with a matrix [ h - g g h ] where g, h are integers which are given, from integers a 1 , a 3 , a 5 , a 7 , by g=a 1 2 −a 7 2 + 2 a 3 a 5 , h=a 3 2 −a 5 2 + 2 a 1 a 7 , respectively; means for linearly quantizing the global signal candidates (p 3 (0) , p 5 (0) ) with step sizes of real numbers L 3 , L 5 to obtain global quantization value candidates (pq 3 (0) , pq 5 (0) ) and quantization residuals (r 3 (0) , r 5 (0) ); means for subtracting the global quantization value candidates (pq 3 (0) , pq 5 (0) ) from the quantization values (Xq 3 , Xq 5 ) to obtain local quantization value candidates (sq 3 (0) , sq 5 (0) ); means for determining an index I from the quantization residuals (r 3 (0) , r 5 (0) ); means for determining local quantization values (sq 3 , sq 5 ) and global difference signals (Δp 3 , Δp 5 ) from the local quantization value candidates (sq 3 (0) , sq 5 (0) ) based on a fifth numeric table selected using the index I; and means for adding the global difference signals (Δp 3 , Δp 5 ) to the global signal candidates (p 3 (0) , p 5 (0) ) to calculate the global signals (p 3 , p 5 ).
Claim 2
Dependent Claim
614 words
A reversible transform coding system which includes a reversible transformer which inversely transforms quantization values (Xq 1 Xq 7 , Xq 3 , Xq 5 ) into an integer four-element vector (u 4 , u 5 , u 6 , u 7 ), said reversible transformer including: means for calculating global signals (p 3 , p 5 ) and local quantization values (sq 3 , sq 5 ) from the quantization values (Xq 3 , Xq 5 ); means for determining quantization residuals (r 1 , r 7 ) from the local quantization values (sq 3 , sq 5 ) based on a third numeric table, means for multiplying the quantization values (Xq 1 , Xq 7 ) by natural numbers k 1 , k 7 and adding the quantization residuals (r 1 , r 7 ) to the products to obtain transform coefficients (X 1 , X 7 ), respectively; means for determining representative elements (s 3 , s 5 ) from the transform coefficients X 1 , X 7 based on a fourth numeric table; means for adding the representative elements (s 3 , s 5 ) to the global signals (p 3 , p 5 ) to obtain transform coefficients (X 3 , X 5 ); and means for linearly transforming the transform coefficients (X 1 , X 7 , X 3 , X 5 ) with an inverse matrix to a matrix [ a 1 a 7 a 3 a 5 a 7 - a 1 - a 5 a 3 a 3 - a 5 - a 7 - a 1 a 5 a 3 - a 1 a 7 ] - 1 to obtain the integer four-element vector (u 4 , u 5 , u 6 , u 7 ), wherein said means for calculating global signals (p 3 , p 5 ) and local quantization values (sq 3 , sq 5 ) from the quantization values (Xq 3 , Xq 5 ) includes: means for calculating global signal candidates (p 3 (0) , p 5 (0) ) from the quantization values (Xq 3 , Xq 5 ) based on two dimensional division with a matrix [ h - g g h ] where g, h are integers which are given, from integers a 1 , a 3 , a 5 , a 7 , by g=a 1 2 −a 7 2 + 2 a 3 a 5 , h=a 3 2 −a 5 2 + 2 a 1 a 7 , respectively; means for linearly quantizing the global signal candidates (p 3 (0) , p 5 (0) ) with step sizes of real numbers L 3 , L 5 to obtain global quantization value candidates (pq 3 (0) , pq 5 (0) ) and quantization residuals (r 3 (0) , r 5 (0) ); means for subtracting the global quantization value candidates (pq 3 (0) , pq 5 (0) ) from the quantization values (Xq 3 , Xq 5 ) to obtain local quantization value candidates (sq 3 (0) , sq 5 (0) ); means for determining an index I from the quantization residuals (r 3 (0) , r 5 (0) ); means for determining local quantization values (sq 3 , sq 5 ) and global difference signals (Δp 3 , Δp 5 ) from the local quantization value candidates (sq 3 (0) , sq 5 (0) ) based on a fifth numeric table selected using the index I; and means for adding the global difference signals (Δp 3 , Δp 5 ) to the global signal candidates (p 3 (0) , p 5 (0) ) to calculate the global signals (p 3 , p 5 ).
Claim 3
Dependent Claim
264 words
A reversible transform coding system as claimed in claim 1 , wherein said means for calculating global signal candidates (p 3 (0) , p 5 (0) ) from the quantization values (Xq 3 , Xq 5 ) includes: means for multiplying the quantization values Xq 3 , Xq 5 by the real numbers L 3 , L 5 to obtain quantization representative values (Xq 3 L 3 , Xq 5 L 5 ), respectively; means for transforming the quantization representative values (Xq 3 L 3 , Xq 5 L 5 ) with an inverse matrix [ h - g g h ] - 1 to the matrix [ h - g g h ] represented using g, h which are given, from integers a 1 , a 3 , a 5 , a 7 , by g=a 1 2 −a 7 2 + 2 a 3 a 5 , h=a 3 2 −a 5 2 + 2 a 1 a 7 , respectively, to transform points (w 3 , w 5 ); means for raising fractions of the inverse transform points w 3 , w 5 or discarding fractions of the inverse transform points w 3 , w 5 to convert the inverse transform points w 3 , w 5 into integers w 3 ′, w 5 ′; and means for transforming a vector (w 3 ′, w 5 ′) composed of the integers w 3 ′, w 5 ′ with the matrix [ h - g g h ] to obtain the global signal candidates (p 3 (0) , p 5 (0) ).
Claim 4
Dependent Claim
535 words
A reversible transform coding system which includes a reversible transformer which produces eight signals of x 0 , x 1 , x 2 , x 3 , x 4 x 5 , x 6 , x 7 , from eight transform coefficients of quantization values Xq 0 , Xq 1 , Xq 2 , Xq 3 , Xq 4 , Xq 5 , Xq 6 , Xq 7 , said reversible transformer including: means for performing inverse transform as recited in claim 2 for the quantization values Xq 1 , Xq 7 , Xq 3 , Xq 5 , to obtain a vector of quantization values (u 4 , u 5 , u 6 , u 7 ); means for performing dequantization based on an integer matrix given by [ a 2 a 5 a 6 - a 2 ] - 1 where a 2 and a 6 are integers for the quantization values (Xq 2 , Xq 6 ) and performing transform for the dequantized values with an inverse matrix to the matrix to obtain a vector of quantization values (v 1 , v 3 ); means for performing dequantization based on a matrix [ 1 1 1 - 1 ] - 1 for the quantization values (Xq 0 , Xq 4 ) and performing transform for the dequantized values with an inverse matrix to the matrix to obtain a vector of quantization values (v 0 , v 2 ); means for performing dequantization based on the matrix [ 1 1 1 - 1 ] - 1 for the quantization values (v 0 , v 1 ), (v 2 , v 3 ) and performing transform for the dequantization values with an inverse matrix to obtain a vectors of quantization values (u 0 , u 1 ), (u 2 , u 3 ) respectively; and means for performing dequantization based on the matrix [ 1 1 1 - 1 ] - 1 for the quantization values (u 0 ), u 4 ), (u 2 , u 6 , u 1 , u 5 , (u 3 , u 7 ) and performing transform for the quantization values with an inverse matrix to the matrix to obtain the signal (x 0 , x 7 ), (x 1 , x 6 ), (x 3 , , 4 ), x 2 , x 5 , respectively where said reversible transformer includes, in place of said means for performing dequantization based on an integer matrix given by [ a 2 a 5 a 6 - a 2 ] - 1 where a 2 and a 6 are integers for the quantization values (Xq 2 , Xq 6 ) and performing transform for the dequantized values with an inverse matrix to the matrix to obtain a vector of quantization values (v 1 , v 3 ), means for multiplying the quantization values (Xq 2 , Xq 6 ) by 13 to obtain a vector, linearly transforming the vector with an inverse matrix to the matrix given above obtained where the integers a 2 , a 6 are 12, 5, respectively, and rounding off results of the linear transform to obtain the quantization values (v 1 , v 3 ).
Claim 5
Dependent Claim
43 words
A reversible transform coding system as claimed in claim 3 , wherein the integers a 1 , a 3 , a 5 , a 7 are 5, 4, 3, 1, respectively, and the integers a 2 , a 6 are 12, 5, respectively.
References Cited (Backward Citations)
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