A method for calibrating and converting colours of a digital image (S i) into printer specific colorant control values (S p), the method comprising the steps of: a) calibrating a specific printer of a printer type according to a printer type specific procedure, wherein for each colorant separately a one-dimensional relationship between a printer tone value (S o) and a colorant control value (S p) is established; b) profiling the printer type to establish a profile combination (CMP i, CMP o) that defines a relationship between colour values in an image colour space (S i) and the printer tone values (S o); c) deriving from the profile combination a one-dimensional relationship (LUT bp) between a black component in the image colour value (K i) and a corresponding black component in the printer tone value (K o) by the steps of: c1) determining a lightness (L i) corresponding to an input black channel value (K i); c2) determining an equivalent G7 channel value (K G7) for this lightness (L i) in dependence on the no-coverage lightness (W i) and the full coverage lightness (B i) on the input side; c3) determining an output lightness (L o) for the G7 channel value (K G7) in dependence on the no-coverage lightness (W o) and the full coverage lightness (B o) on the output side; and c4) determining a black printer tone value (K o) from the output lightness (L o); d) converting an image colour value (S i) with the one-dimensional relation (LUT bp) if all but the black component (K i) in the image colour value (S i) are lower than a predefined threshold, otherwise converting an image colour value (S i) with the profile combination (CMP i, CMP o), and e) converting the image colour value (S i) with the calibration relations established in step a) to obtain the colorant control values (S p). a) calibrating a specific printer of a printer type according to a printer type specific procedure, wherein for each colorant separately a one-dimensional relationship between a printer tone value (S o) and a colorant control value (S p) is established; b) profiling the printer type to establish a profile combination (CMP i, CMP o) that defines a relationship between colour values in an image colour space (S i) and the printer tone values (S o); c) deriving from the profile combination a one-dimensional relationship (LUT bp) between a black component in the image colour value (K i) and a corresponding black component in the printer tone value (K o) by the steps of: c1) determining a lightness (L i) corresponding to an input black channel value (K i); c2) determining an equivalent G7 channel value (K G7) for this lightness (L i) in dependence on the no-coverage lightness (W i) and the full coverage lightness (B i) on the input side; c3) determining an output lightness (L o) for the G7 channel value (K G7) in dependence on the no-coverage lightness (W o) and the full coverage lightness (B o) on the output side; and c4) determining a black printer tone value (K o) from the output lightness (L o); c1) determining a lightness (L i) corresponding to an input black channel value (K i); c2) determining an equivalent G7 channel value (K G7) for this lightness (L i) in dependence on the no-coverage lightness (W i) and the full coverage lightness (B i) on the input side; c3) determining an output lightness (L o) for the G7 channel value (K G7) in dependence on the no-coverage lightness (W o) and the full coverage lightness (B o) on the output side; and c4) determining a black printer tone value (K o) from the output lightness (L o); d) converting an image colour value (S i) with the one-dimensional relation (LUT bp) if all but the black component (K i) in the image colour value (S i) are lower than a predefined threshold, otherwise converting an image colour value (S i) with the profile combination (CMP i, CMP o), and e) converting the image colour value (S i) with the calibration relations established in step a) to obtain the colorant control values (S p).