Abstract
A video printer using thermal dye transfer method makes high quality images with its half tone control system. Recently a few kinds of printed images with a little bit of density difference in gray balance, such as graphic images or overlaid images are reported. In case of printing many identical images continuously, there are some differences in image quality, especially in gray balance, between the first print and the last one. So we have checked the reason and investigated the method for improving the quality of gray balance.
Before trying to examine the half tone control system, we have studied the relationship between the printed image and the detected temperature of the thermal head. We have made investigation into compensating the optical density with switching the data banks for gamut according to the head temperature. To realize this new method to compensate the optical density, it was important to clarify the limit of the density step caused by data switching. It is very effective for density compensation to increase the number of data banks and the key data for the compression of gamut data in half tone control. After all these investigations, we have reduced the density error by half.
