SUITABLE DELTA-D FOR TONE REPRODUCTION AND SPATIAL-FREQUENCY OF IMAGES

We investigated the value of DELTAD (the density interval for 1.30 log H units) that is suitable for current black-and-white photographic sys tems. We first evaluated the quality of prints for different DELTAD va lues and then explored the effect of spatial frequency content of the image on the suitable DELTAD that provides preferred gradation, using simulated images of photographic prints on a computer-controlled CRT. This experiment was conducted to examine whether or not the suitable D ELTAD depends on the scene. Results show that (1) the suitable DELTAD is less than 0.80, which is accepted for the ISO method, and that (2) the suitable DELTAD depends on the spatial frequency content of the im age.