Image analysis – Image compression or coding – Predictive coding
Patent
1995-06-14
1998-05-12
Boudreau, Leo
Image analysis
Image compression or coding
Predictive coding
341107, 382232, G06K 936, G06K 946, H03M 700
Patent
active
057518599
ABSTRACT:
Bilevel textual images are compressed by segmenting the image into marks (401) and then coding each mark using a soft pattern matching method. Each mark is compared (403) with the marks in a library of marks and if an acceptable match is found (404), the index of the matching mark is coded (412). Each pixel in a current mark is then coded using a statistical coder that codes each pixel based on the value of the pixel and a set of probabilities of all sample values based on a context that consists of pixels in the current mark and pixels in the matching mark (414, 415, 416, 417). In order to reduce the overall bit count of the image, pixels which color-reversed (706, 709) prior to coding, if so doing will not perceptibly alter a reconstructed image (708). If a matching mark is not found among the marks in the library, each pixel in the mark is coded using a statistical coder using a context of pixels in the non-matching mark (406, 407, 408, 409, 410). Again, pixels which are poorly predicted (721) are color-reversed (722, 725) prior to coding if the reversed pixels will not perceptibly alter the image (724).
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Boudreau Leo
Chen Wenpeng
Gurey Stephen M.
Lucent Technologies - Inc.
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