HutchColor HCT, Руководство пользователя

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HCT User Guide page 14
Copyright © 2001 HutchColor, LLC User_Guide_43.docx 2/10/19
associate those falsely-light RGB values with the true “darkness” (L*) of what is really a very dark
patch. This means the profile will add density to images with less scanner flare.
An 'extended range' profile will often solve this problem.
Darkness caused by viewing conditions
Another explanation for the apparent 'darkness' of 35mm profiles is that 35mm transparencies
submitted for reproduction are usually selected under non-standard viewing conditions that make
them seem lighter than if they were viewed on a normal light box. For example, 35mm slides are
usually viewed under a magnifying loupe or on a slide projector which produces a pure-black
surround. Unless the eye can simultaneously see some of the illuminating source at the side of the
image (e.g. part of the light box), we have no way of judging relative brightness, or exposure, so
even a quite dark image can look pleasing when it would look too dark if seen on a light table. The
same thing happens when 4x5 or 8x10 inch transparencies are viewed inside a black mask.
For this reason, a scanner profile that works well for 4x5 or 8x10 inch transparencies viewed on a
light box (with some surrounding area of white) will usually SEEM too dark when used on 35mm
transparencies, or larger transparencies viewed inside a black mask.
The simple solution is to make an “auto-lightening” profile, as described below.
Auto-lightening profiles
If, after setting white and black (e.g. with Photoshop Levels), all scans seem consistently too dark,
you can build a lightening effect into the scanner profile by DARKENING the HCT scan slightly with a
simple curve or levels adjustment. This fools the profiling software into believing the darkness is a
scanner characteristic, which it 'corrects' with a complimentary amount of lightening. If you adjust
the darkening curve to suit your average original, most images will look pleasing after assigning the
profile and setting white and black.
Just remember an auto-lightening scanner profile that works well for 35mm scans may cause large-
format or normally-exposed transparencies to appear too light.