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Re: filmscanners: ColorSteps?
I ran into a problem with Photoshop 4.01 on the PC where it posterized
badly when I did levels adjustments in 16 bit. The problem did not
occur if I worked in 8 bit. It usually happened in midtones going quite
I never printed these so, I have no idea what they would have looked
like. However, I was told by some it was probably a graphic/video card
driver problem. I had upgraded to the newest version, so I contacted
Diamond, my videocard manufacturer. They admitted there were some
incompatibilities with the card I had and Photoshop, and suggested I
update the card on a trade in basis.
On a last attempt, I upgraded to Photoshop 5.0, and magically the
problem went away, so it was either a PS and Diamond problem, or a PS
only problem, but it's gone now, and I did not replace my videocard or
have I upgraded the driver since.
I recognize your situation is on a Mac, and I don't know if any of this
relates, but obviously PS Version 4 for Windows was buggy.
Richard Starr wrote:
> --- You wrote:
> You will be able to chack whether it is the file, or a problem with the
> display/graphics system, by viewing the histogram. Contouring shows up as
> missing bit values, leaving the histogram looking like a mangy dog's comb.
> What file type is this, and what processing has been done (and by what) en
> route to the screen? And what scanner/software?
> --- end of quote ---
> Thanks for the answers to this. I am still finding my way with my
> Nikon 3510AF. Full resolution scans take 15 minutes and correcting the color
> misregistration takes 10 more. Until I can afford a modern scanner, I'm still
> in the dark ages. The film in one case is either Kodak 1000 negative film or
> 800 negative film from maybe Agfa. Definitley available light material shot
> my little Olympus XA4 (a jewel.) I would have done some curves or gamma
> adjustments in Photoshop. Maybe a curves adjustment in the Nikon software for
> one of the pictures.
> The odd thing is that the posterization seems to show in the display and not
> the print. This suggests a bug somewhere in the software or hardware. It's
> Photoshop 4.0.1 on a SuperMac with an ATI video board and a Sony monitor.
> all good stuff.
> Still, this Photoshop version is a little buggy, I think. I used to use
> version on a 68000 Mac and it worked better with regard to previews anyway.
> the PPC Mac (it installs as a ppc version) checking and unchecking preview
> boxes may or may not affect the display depending on the thing being
> When the display is previewed, the adjustment affects the whole screen, so
> background becomes magenta or darker or whatever. It's hard to make subtle
> judgements that way even if the image fills most of the screen. I don't think
> the 68k Mac version did these things. Maybe later versions don't.
> (Holding the mouse down on the drag strip of the control window in many
> functions does cause the display to go back to the unpreviewed version in some
> of the control windows but not all. This seems to me to be sloppy
> probably corrected in later versions. )
> So given these little probs with Photoshop, maybe there is something that
> slightly unreliable display.