Wood photography using light irradiation and heat treatment

To apply the coloring method using light irradiation and thermal treatment to print photographs on wood, the effect of the transmittance of negative films was investigated. DeltaE* decreased with light irradiation when specimens covered with films with transmittances exceeding 20% were irradiated for 100 h. It was thought that this phenomenon was due to the decrease in Deltab*. The color of light-irradiated wood changed remarkably with thermal treatment; however, the change in the color of exposed specimens covered with films with transmittances exceeding roughly, 20% became constant. Clear photographs could be printed on wood using negative films with transmittances less than approximately 20%. Furthermore, the difference between the maximum and minimum values of DeltaE* after thermal treatment was about 22. Humans can distinguish four to seven colors that can be created by this method. (C) 2004 Wiley Periodicals, Inc.