The invention provides a method and apparatus for compressing and decompressing electronic image data, and in particular texture data. The compressed data comprises at least two sets of reduced size data, modulation data and modulation and discontinuity flags. The modulation and discontinuity flags determine how the modulation data is used, in combination with the reduced size data sets, in a decompression process. The invention allows for data decompression of textures including large color discontinuities.