Process and device for the transformation of image data
AssigneeDeutsche Thomson-Brandt GmbH
InventorsHeinz W. Keesen, Edgar Peters
Life of this patent
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Abstract
A video signal processing system includes encoder apparatus applying a Discrete Cosine Transform (DCT) to N.times.N (e.g., 8.times.8) image data blocks. Resulting DCT coefficients are further transformed by multiplying them with a special transform matrix of predominantly zero values. A comparator determines whether the original DCT coefficients or the further transformed DCT coefficients will be coded for data compression, with respect to static or dynamic image content. Complementary transformation is performed at a decoder.
Claims12
In a system for encoding image representative data, apparatus including:
- means for transforming image data into blocks containing rows and columns of coefficients respectively representing transformed values of image data within each said block;
- special transform means for multiplying each column of coefficients by a comparison matrix having rows and columns of predominantly zero values;
- means for providing a comparison of (a) a first sum of predetermined coefficient values and (b) a second sum of predetermined modified coefficient values resulting from said multiplying by said comparison matrix, for producing at an output coefficients associated with the smaller of said first and second sums;
- and
- means for coding output coefficients from said comparison means to produce a coded output signal.
In a system for transforming and encoding image representative data, apparatus including:
- line-to-block converter means for converting image representative lines into a plurality of image data blocks defined by a predetermined number of rows and columns;
- two-dimensional transform means for providing first coefficients respectively representing transformed values of image data within each said block;
- special transform means for multiplying said first coefficients by a comparison matrix having predominantly zero values which, in the case of dynamic image content, produces a coefficient distribution approximating static image content with correspondingly modified coefficients;
- signal delaying means;
- comparison means for receiving said first coefficients via said delaying means at a first input and for receiving modified coefficients from said special transform means at a second input, said comparison means providing a comparison of (a) a first sum of predetermined first coefficient values and (b) a second sum of predetermined modified coefficient values resulting from said multiplying by said comparison matrix, said second sum being derived from at least a bottom row of a matrix of modified coefficients produced by said multiplication with said comparison matrix, said comparison means producing a signal indicating the results of said comparison as to which of said first and second sums is smaller, said comparison means providing at an output coefficients associated with the smaller of said first and second sums;
- means for coding output coefficients from said comparison means to produce a coded output signal;
- and
- means for combining said indicating signal with said coded output signal.
Dependencies are inferred from the claim text.