Is there some way to calculate the optimum texture size based on the size of th render? I just checked the Poser Gallery here  and with the exception of one image at 1600x2000 render all the images were under 1024 on the long side. If we use the the big image as a standard shouldn't the largest texture needed be somewhat less than 2000 on the long side? Even on that image the total area of the face was 680x840 so theoretically a 1000x1000 texture would be adequate right? It seems twice that would be safe. However 4096x4096 does seem the standard for a high resolution texture.

I am looking for a way to sample down all the images in mt texture folder to under 1600x1600 without enlarging the smaller images. The textures I have done individually so far are often 4000x4000 clearly blown up from a source probably half that size... when I reduce them to 1600x1600 the difference is quality in the final render is completely indistinguishable even when the render is 1600x1600. I have found even stuff like hair textures have been up-sampled by the vendor and look the same reduced to 50% resolution.

I really would appreciate help finding something to bulk down size all my textures. I have download a dozen shareware apps but none are appropriate for tackling folder with sud-directories and maintaining aspect.

Anyway, it is clear you are not up-sampling your source but I wonder if you could determine the appropriate resolution based on what the largest render is that anyone has done to date.