Abstract: Disclosed is a variable-length image compression arrangement which represents successive distinct image data values (220, 221) of an image using corresponding non-decreasing Palette values (215, 222), and which incorporates (915, 1025) into the encoded data stream information recording the position in the encoded data stream at which each Palette value bit representation length increase occurs.

Abstract: Disclosed is a variable-length image compression arrangement which represents successive distinct image data values (220, 221) of an image using corresponding non-decreasing Palette values (215, 222), and which incorporates (915, 1025) into the encoded data stream information recording the position in the encoded data stream at which each Palette value bit representation length increase occurs.

Abstract: Disclosed is method of encoding a set of data values (205-245). Each data value corresponds to a pixel position (205,210, 220,225) within an image (100). The method operates on a current (230) said data value at a current pixel position. The method creates (605) a context set (215,225) for the data value (230), the context set including a data value at a pixel position (225) in the set immediately preceding the current pixel position in an encoding order, wherein the immediately preceding pixel position is not adjacent said current pixel position within said image. The method then encodes (500) the data value (230) using the created context set (215,225). A corresponding decoding method is also provided.

Abstract: A Hybrid Compressor (304) and method (500) of compressing a tile (2200) of pixels within an image are disclosed. An Edge Processor (404) of the Hybrid Compressor (304) analyses pixel runs (403) of the tile (2200) and generates boundary data defining one or more regions comprising pixels of substantially identical colour. A Palette Processor (411) of the Hybrid Compressor (304) generates data defining a colour value for each region. An Image Processor (416) of the Hybrid Compressor (304) generates a representation of pixels not included in the one or more regions.