[filmscanners] Re: Advice on scanner settings

["gary" <lists@lazygranch.com>]

How about just changing the opacity and slide between one version and
the other, and look for differences.

I don't think printing is as accurate as looking on a monitor.

Preston Earle wrote:
> "Arthur Entlich" asked: "Anyone have a good idea how to check two images for
> changes against one another such that hue, color, contrast, brightness or
> any value change to a pixel would show up clearly as a changed pixel when
> comparing two images on top of one another?   I would like to see a
> quantitative visual indication of each pixel that is altered by a certain
> jpeg setting relative to the non-jpegged tiff."
> -------------------------------------
>
> One thought: flatten the "black" image and look at the Levels of that file.
> I think you'll find a lot of pixels of 0, 1, and 2 values. I suspect there
> will be few pixels of 6 or more value. This will give some idea of the
> quantity of changes in the JPEG file. (or maybe 255, etc., values. I never
> can remember whether 0 is black or white.)
>
> Second thought: make the "best" print possible of the two files and compare
> the two prints. This will give some idea of the quality of the changes. If
> you can see the difference in the two files without looking at the files at
> 200+% on pixel-for-pixel basis, I'd say you've got better eyes than 100% of
> other folks in the world.
>
> For really poor slides that need a lot of post processing, I think it makes
> sense to start with a TIFF file and convert to JPEG only after all image
> correction has been done. For slides where the first scan look pretty good,
> I doubt you can do any reasonable changes that would show a difference in
> starting with a JPEG or TIFF.
>
> Preston Earle
> PEarle@triad.rr.com
> www.sawdustforbrains.blogspot.com
>
>
>

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