Method of compressing image data

A method of compressing image data (10) that comprise a plurality of pixel values, each pixel value being associated with a respective pixel (12) of a plurality of pixels (12), wherein the pixels (12) are provided in an arrangement of rows (16) and columns (14), with each row (16) or column (14) corresponding to a pixel alignment having a predetermined order (R) of pixels (12),

• wherein the pixel values for at least some of the plurality of pixels (12) are encoded in accordance with the following steps:
• associating the respective pixel (12′) with one of a plurality of pixel groups in accordance with a predetermined grouping scheme, with each of the plurality of pixel groups being defined by the pixels of a plurality of predetermined pixel alignments (14, a, u) or by a subset of pixels of a plurality of predetermined pixel alignments (14, a, u);
• determining an estimated pixel value of the respective pixel (12′) in dependence on the pixel value associated with at least one predetermined other pixel (12″, 22, 24) while using at least one estimation rule, with the at least one predetermined other pixel (12″, 22, 24) being selected in dependence on the pixel group of the respective pixel (12′);
• forming a difference value (D1, D2, D3) of the respective pixel (12) that corresponds to a predetermined relation between the pixel value associated with the respective pixel and the estimated pixel value of the respective pixel (12′);
• and
• encoding the difference value (D1, D2, D3) using an encoding process.