Suitable ΔD for tone reproduction and spatial frequency of images

We investigated the value of ΔD (the density interval for 1.30 log H units) that is suitable for current black-and-white photographic systems. We first evaluated the quality of prints for different ΔD values and then explored the effect of spatial frequency content of the image on the suitable ΔD 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 ΔD depends on the scene. Results show that (1) the suitable ΔD is less than 0.80, which is accepted for the ISO method, and that (2) the suitable ΔD depends on the spatial frequency content of the image.