In an example, a method includes obtaining, by processing circuitry, a mapping from at least one measured color characteristic of a first substrate to at least one measured color characteristic of a second substrate, wherein the at least one measured color characteristic of the first substrate comprises a measured color characteristic of an unmarked portion of the first substrate and the at least one measured color characteristic of the second substrate comprises a measured color characteristic of an unmarked portion of the second substrate. In some examples the method further includes applying, by processing circuitry, the mapping to a first color which is obtained when applying at least one colorant according to a first colorant specification on the first substrate to determine a predicted color to be obtained by applying at least one colorant according to the first colorant specification on the second substrate.