COMPRESSING AND DECOMPRESSING IMAGE DATA USING COMPACTED REGION TRANSFORMS

A method of compressing a set of image value data items each representing a position in image-value space so as to define an occupied region thereof. A series of compression transforms is applied to subsets of the image data items to generate a transformed set of image data items occupying a compacted region of value space. A set of one or more reference data items is identified that quantizes the compacted region in value space. For each image data item in the set of image data items, a sequence of decompression transforms is identified that generates an approximation of that image data item when applied to a selected one of the reference data items. Each image data item is encoded as a representation of the identified sequence of decompression transforms for that image data item. The data items and the decompression transforms are stored as compressed image data.