A method and system thereof for processing image data. Uncompressed image data comprising a plurality of pixels representing an image to be rendered are received. The pixels are grouped into blocks such that the pixels in a block have substantially the same color values. The image data including the blocks of pixels are compressed and the compressed data are used as the basis for generating a rendered image. The maximum number of pixels per block is dependent on the resolution at which the image may be rendered; at higher resolutions, more pixels are included in a block than at lower resolutions. However, the maximum physical dimensions of rendered blocks in the rendered image are not changed as a function of resolution; the maximum block size in an image rendered at one resolution is the same as that at another resolution.