In an image-encoding scheme, an input image is decomposed into several image blocks (600) comprising multiple image elements (610), e.g. pixels or texels. The image blocks (600) are then encoded into encoded block representations (700). Such a block representation (700) comprises a color codeword (710), an intensity codeword (720) and a sequence (730) of intensity representations. The color codeword (710) is a representation of the colors of the image elements (610) of the block (600). The intensity codeword (720) is a representation of a set of multiple intensity modifiers for modifying the intensity of the image elements (610) in the block (600). The representation sequence (730) includes an intensity representation for each image element (610) in the block (600), where a representation identifies one of intensity modifiers in the intensity modifier set. During decoding, the color and intensity codewords (710, 720) and intensity representations (730) are used to generate a decoded representation of the image elements (610) in the block (600).