OK. As promised (pat, pat), here's an explanation of what I think is going on, without a lot of techie words. Please, if anyone really knows what they are doing, jump in and help! (a If we start with something that is essentually a continuous tone image, (b photograph it with B&W film, and look at it under a microscope, we see lots of tiny black dots. Silver "grains" are sensitive to light, and it is either an all or nothing thing. When they are developed, the entire grain turns completely black or is completely washed away. There are some complications to this, like grains can sometimes convince touching grains to also turn black, causing "clumping." So essentually a B&W negative (I've cheated a little here....) is a microscopic "dither" of black dots. Much like a newspaper halftone, but down at microscopic dimensions. [Color works similarly, but different.] (c If we scan this negative with a low resolution scanner, each CCD pixel sensor averages over a square little area. If the size of the pixel area is large compared with the grain size, the average in a given brightness area will have little variation. The pixels will all look very nearly the same for a given tone. Since these pixels are large, the edge between tones has a noticable stair-step. (d If the resolution of our scanner gets better, per pixel we are not averaging as many grains, so slight variations in the number of grains starts to show up. Notice the dark gray area is starting to look "mottled." Of course, since the pixels are smaller, the edge has a finer stairstep. (e When the resolution gets so fine, approaching the actual grain size, there may be hole grains or partial grains per pixel. The sensor just records the average, and this average can vary by quite a lot. Compare (e with (b, definitely splotchier. (f And applying unsharp mask just makes things worse. ________ (b' One way (maybe not a good way) to fix this is to blur the negative a tiny amount by defocusing the optics. (e' The de-focused scan looks much smoother in the solid gray areas. The edge is not as good as in (a, but is quite a lot better than in (c. _____ (g If I try to fix the blotchy scan (e, by maybe Gaussian blurring and sharpening, all I get are blurred, sharpened, mottles. The software like GrainSurgery, etc. is really much more sophisticated, and actually works quite well.

i think i'm gonna stick to the darkroom after all this is said and done....