Hi, I think "posterization" is the term you are looking for. You can
check it out in Photoshop by selecting the area and examining the
histogram (levels). Very interesting that it prints out okay! Sorry I
don't have any idea what the cause is.
Jon
ps "grain aliasing" just looks like a grainy image.
--- Richard Starr <Richard.Starr@valley.net> wrote:
> I don't know if color steps is the right term but it seems to be a
> display
> problem. In several high resolution scans, I've seen some odd areas
> of color
> that should be continuous appear to step from one tone to another as
> though
> displayed in 256 colors or fewer. One was a reflective surface with
> some
> specualr highlighs (a polished truck fender) and another was may
> daughter's
> softly lit cheek. It's a high res 24 bit Photoshop display on the
> Mac, on a
> Sony Trinitron monitor. I was thinking there was somthing odd about
> my antique
> scanner, but the colors are smooth and continuous in the Epson print.
>
> One example is from an Ektachrome slide, the other from a high speed
> negative
> film. I thought of the grain aliasing discussed on the list, but I'm
> not sure
> what it looks like. It appears in all zoom settings of the display,
> so aliasing
> with scan lines wouldn't explain it.
>
> In the display it almost looks like the kind of color reversal you
> can get when
> you bend a curve too far. It don't show in the print though...
> weird.
>
> Any ideas?
>
> Rich
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