Abstract: A technique for use in, illustratively, a transform coder for imparting robustness against burst (or similar) errors to data patterns, such as illustratively two-dimensional image data, that exhibit local redundancy. Robustness is provided, in the case of images, by passing localized (blocked) image data, i.e. either pixel values or transformed, illustratively discrete cosine transform (DCT), image coefficient values therefor, through a global block transform, such as a global block Hadamard transform, prior to compression coding in order to produce "holographic-like" compressed data for subsequent transmission and/or storage. Specifically, globally transforming an image in this fashion effectively spreads (diffuses) the image data in each block of pixels in that image or in the transform coefficients therefor in a regularly ordered pre-defined global manner throughout the entire image to create what is, in effect, intentionally "smeared" image data.

Abstract: In an image in which some pixels in some rows of an image have values associated therewith, apparatus and method of processing, for subsequent entropy coding or decoding, graylevel data for the remaining pixels in the image.

Abstract: A gray scale filter for image data is described which forces a least significant bit of a current pel equal to a most significant bit of the current pel when the most significant bit of the current pel is equal to the most significant bit of a previous and a next pel on a scan line of an image. The invention is embodied in a logic structure employing exclusive ORs to make comparisons between the previous, next and current pels and logic gates to gate the value of the most significant bit of the most current pel to an output representing a filtered least significant bit of the current pel. It should be noted that the value of the most significant bit of the current pel is not changed since only changes between gray-white and white or gray-black and black are filtered by the present invention.