A computer-implemented method comprises receiving a first compressed representation of a texture map in a first compression format, wherein the first compressed representation has been compressed using a first compressor, and receiving an array of compression parameters for a second compressor, the array of compression parameters including one or more respective compression parameters for each of a plurality of pixel regions of the texture map. The method further comprises decompressing the first compressed representation of the texture map to obtain the texture map, and compressing, using the second compressor, the texture map to a second compressed representation in a second compression format, comprising compressing each of said plurality of pixel regions of the texture map in accordance with the respective one or more compression parameters. The method further comprises storing the second compressed representation of the texture map to one or more memories accessible by a graphics processing unit, and selectively decompressing portions of the second compressed representation of the texture map using the graphical processing unit.