Noriyuki SHIMANO

Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashi-osaka, Osaka, 577-8502 Japan

(Received April 28, 1998; Accepted June 30, 1998)

Colorimetric calibration of color imaging devices is important to realize device independent color reproductions. However the calibration for digital or video cameras is difficult because a color image is acquired for unknown objects under various unknown illuminants. An experiment was carried out based on two computational color constancy models, the finite-dimensional linear model and the spectral sharpening model, to estimate colorimetric values using image data of a color chart captured by video camera. We estimated the colorimetric values by using a single reference reflectance with known spectral reflectance in a color chart under an unknown illuminant. The accuracy was evaluated by color differences in CIELAB color space and was compared on three different color charts under three different illuminants including a fluorescent lamp. It was confirmed that the two computational models do not require prior knowledge of illuminants and surfaces. The finite-dimensional linear model gave more accurate results than the spectral sharpening model in the simulations and experiments.

Key words : colorimetric calibration, color reproduction, image acquisition, computational color constancy

shimano@me2.kindai.ac.jp