At 02:31 17/07/03, Laurie Solomon wrote:
>green on a slide
>represents green and is caputred as green while on negative film green
>represents its complimentary color while being captured by the scanner as
>green. However, in the case of negative film, this green is compromised by
>the addition of the color mask so it may not even present the same
>uncontaminated green that positive film would present nor the exact
>complement of its complementary color without some manipulation to remove
>the film mask and uncontaminate the color.
I think what shaf was saying is that if the scanner is accurately
calibrated color-space-wise, then it will take from the neg film the
'exact' colors as they are recorded on the neg film, complete with the
color biases, the mask etc. Then, because you have an accurate color
rendition you can apply a known transfer function to convert to positive by
removing the mask, inverting and allowing for color bias. To do this you
have to know the characteristics of the neg film - which differ film to
film - but at least you have a known starting point if you have the
'calibrated' color in the first place.
I know bugger-all about profiling, and have 1000 questions on the subject,
so looking for feedback here if this is not true.
I really get confused by what is the meaning of a color space vs "absolute
color". It seems to me that your (shaf's) explanation does not address the
fact that there is no such thing as "absolute" color, and once you conceive
of such a thing as a color space, the whole thing becomes much more
complicated. For example...
If my scanner is set up accurately and is profiled for RGB. I think this
means that the scanner is set up to convert whatever it sees on a slide
into a digital number representing the nearest best color that is available
in RGB color space. Is this true?
Now what does it mean to say that a MONITOR is profiled for RGB color
space? Does it mean that it assumes that the source digital data is "in
RGB", then it translates each digital number _with_that_assumption_ to the
nearest displayable equivalent 'color' on the screen, knowing the
characteristics of the screen?
If my understanding in above is correct, then I have more difficulty in
understanding what Photoshop etc mean when you set up a profile/color space
for them. What does this mean? What is the relationship between Photoshop
color space and the monitor color space when a photoshop image is being
displayed on screen?
Any help including ref to a good basic text welcomed.
Julian
Julian
Canberra, Australia
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