FIELD: information technologies.
SUBSTANCE: input image is exposed to decomposition into several image units (600), containing multiple image elements (610). Image units (600) are then coded into coded units (700), comprising the first code word of colour (710), the second code word of colour (720), code word of colour modifier (730) and sequence of colour indexes (740). Code words of colour (710, 720) are representations of the first and second main colour (10, 20) arranged on the first line (40) in colour space. Code word of modifier (730) is representation of at least one colour modifier for modification of the first main colour (10) along the second line (12) in order to get multiple presentations of colour (30, 32, 34, 35, 36, 38) along line (12). The second line (12) has a different direction (15) compared to the first line (40). Sequence of indexes (740) comprises indexes of colour related to representation of colour selected from i) representations (30, 32, 34, 35, 36, 38) at the second line (12) and ii) at least one representation (31, 33) on the basis of the second main colour (20).
EFFECT: increased efficiency of coding of image comprising two different shades with provision of high quality.
39 cl, 32 dwg, 5 tbl
