Colour proofing apparatus and method

For later use in a flexographic printing operation, a colour proofing apparatus, comprising:

• an engraved printing roller having a pattern of ink accommodating cavities on a peripheral surface thereof,
• an inking arrangement for inking the engraved printing roller with a sample of an ink to be used for printing, the inking arrangement including an ink fountain disposed at a periphery of the engraved printing roller and configured to accommodate, in a volume that is delimited by a part of the peripheral surface of the engraved roller, an amount of ink for inking the peripheral surface of the engraved printing roller by filling the cavities with ink when the cavities pass through the ink fountain,
• a back pressure cylinder forming a nip with the engraved printing roller,
• a passing arrangement for passing a sheet of the print substrate of the type to be used for printing through the nip formed between the engraved printing roller and the back pressure cylinder, thereby to print an ink layer onto the sheet, the passing arrangement including a conveyor adapted to feed a sheet of a print substrate through said nip in synchronism with movements of the peripheral surface of the engraved printing roller and the back pressure cylinder, and
• a measuring apparatus for measuring a colour value of the ink layer, the measuring apparatus including an optical sensor disposed at the conveyor for measuring a colour value of the sheet that has passed through the nip,
• wherein the measured colour value is usable for predicting a colour of a print product obtained in a flexographic print process in which said ink is applied to an anilox roller having a screen corresponding to that of the engraved printing roller in the proofing apparatus, and the ink is then transferred onto a printing cylinder from which it is transferred onto said print substrate.