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Re: color value interpolation from colorbar [message #64125 is a reply to message #64124] Thu, 04 December 2008 11:15 Go to previous messageGo to previous message
j.coenia@gmail.com is currently offline  j.coenia@gmail.com
Messages: 36
Registered: December 2008
Member
The images are digitized, unfortunately, from analog recordings of
medical scanning sessions. This is the reason the colors are not
true. There is no way to retrieve the *exact* colors as they
presumably appeared on the original equipment screen.

Still, the recorded image quality on the tapes is considered good
enough for review and even diagnosis. When radiologists look at these
images, no one objects that the colorbars are incorrect, and that
their reds and yellows don't exactly match the images' reds and
yellows. No one can even tell, in fact. It is however clear to the
human eye which areas are more yellow and which are more red. A
computer should also be able to both find the image colors and assign
interpolated colorbar values for more quantitative analysis.

Even without the errors introduced by analog recording onto tape and
digitization, I can imagine a color-coded image with gradations from
red to yellow too fine to discern with the human eye. A colorbar
could be created with a smaller sampling of discrete representative
hues from most yellow to most red, say 25 hues. A human observer
could interpret such a colorbar. Isn't it possible to write a
computer program to interpolate values to the unknown colors from the
colorspace traversed by a partial colorbar?

Even in the very simple case of a two-hue colorbar, with yellow at 0
and red at 100, we would still interpolate a value for an orange
somewhere between 0 and 100, probably 50, based on certain assumptions
we hold about color gradients. With more intermediate hues and more
gradient values, shouldn't it be possible assign a reasonable value
for that orange?

It's clear that I do not know that much about color theory, but the
motivation for this is that if a human observer can perform rough
color interpolation on corrupted color-coded images, then a computer
should be able to perform finer interpolation.

Thanks

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