In one example, an initial transform is stored for converting wavelength channel responses of a color measurement instrument to color readings. The initial transform is set in-factory by a manufacturer of the color measurement device. A color selection of a sample is subsequently retrieved from a database, where the color selection was made by an end user in response to a color reading by the color measurement instrument using the initial transform. An adjustment to the initial transform is calculated using the color selection. The adjustment is then sent to the color measurement instrument for use in making future color measurements.