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US 5,859,931 AGranted
Image compression and decompression using predictive coding and error diffusion
AssigneeXerox Corporation
InventorsZhigang Fan, Ying-wei Lin
Life of this patent
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Abstract
An encoding/compression technique using a combination of predictive coding and run length encoding allows for efficient compression of images produced by error diffusion.
Claims13
A method for lossless efficient run-length encoding of error diffused halftone images, comprising:
- inputting an error diffused halftone digital signal;
- generating a predicted continuous tone signal from previous error diffused halftone digital signals;
- generating a predicted error diffused halftone digital signal from the predicted continuous tone signal;
- generating a prediction error signal from the error diffused halftone digital signal and the predicted error diffused halftone digital signal;
- and
- run length encoding the prediction error signal.
3 more elements
A method for lossless decompression of a run-length encoded signal, comprising:
- inputting a run-length encoded prediction error signal;
- run length decoding the run-length encoded prediction error signal to form a prediction error signal;
- generating a decoded digital signal from the prediction error signal and a predicted digital signal;
- generating a predicted continuous tone signal from previous decoded digital signals;
- and
- generating the predicted digital signal from the predicted continuous tone signal.
3 more elements
An apparatus for lossless compression of an error diffused halftone digital signal, comprising:
- a prediction circuit which inputs the error diffused halftone digital signal and outputs a predicted digital signal, comprising:
- an averaging circuit which averages a plurality of portions of previous error diffused halftone digital signals and outputs a predicted continuous tone signal, and
- a predicted digital signal generator circuit which inputs the predicted continuous tone image signal and outputs the predicted signal;
- a prediction error circuit which inputs the error diffused halftone digital signal and the predicted digital signal and outputs a prediction error signal;
- and
- a run length encoder which inputs the prediction error signal and outputs a run length encoded prediction error signal.
3 more elements
Dependencies are inferred from the claim text.