Digital Camera Characterization for Color Measurements

The use of spectrophotometers for color measurements on printed substrates is widely spread among paper producers as well as within the printing industry. Spectrophotometer measurements are precise, but timeconsuming procedures and faster methods are desirable. Colorimetrically calibrated flatbed scanners have been proved to provide a fast and fairly accurate alternative to spectrophotometers. Moreover, the rapid development of digital cameras has made it possible to transfer successfully implemented methods for color calibration of flatbed scanners to a camera-based system. Earlier presented methods for color calibration of trichromatic devices have been implemented in the camera-based system and improving modifications are proposed. Furthermore, the performance of the calibration can further be enhanced if the spectral sensitivities of the color filters in the camera sensor can be characterized. Methods for filter characterization are presented together with methods that utilize the camera characteristics to enable color measurements. The findings of this study show how a moderately priced consumer digital camera can be used as a fast and inexpensive alternative to spectrophotometers for color measurements on printed substrates.