A method for optimizing an amount of colors used in content data is described. At least one content object is received and it is analyzed if any of the received content objects is a predetermined type. At least one color used within the at least one content object of the predetermined type is determined and the received content objects are rendered to a raster canvas so that the at least one color is protected. Information on the at least one color is stored and at least one characteristic of the rendered content is compared to at least one predetermined criteria. In case of mismatch the amount of colors used in the content of the raster canvas is optimized so that the at least one color used in at least one rendered content object of the predetermined type is protected. Finally, the content is compressed and output.