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Re: color value interpolation from colorbar [message #64311 is a reply to message #64200] Mon, 15 December 2008 19:49 Go to previous messageGo to previous message
j.coenia@gmail.com is currently offline  j.coenia@gmail.com
Messages: 36
Registered: December 2008
Member
I finally posted the results from the HSV color interpolation function
that was supplied to me. I used the colors it found to recolor the
images from red to yellow, instead of the original black-red-yellow,
which was harder to see. These colors were extruded according to
their interpolated gradient values to produce an animation that I
uploaded to Picasa:

http://picasaweb.google.com/j.coenia/ColorInterpolation?auth key=H9iPrIqxX1c#

I think now that this inefficient HSV interpolation function is not
necessary. As Dr. Fanning says, if the images were generated
correctly by the scanner, then originally the colorbar on them should
contain all the image colors. There are more colors (errors) in this
problem because these images are digitized frame grabs from a session
recorded to videotape from an analog source, but the colors should
still be close enough to extract something meaningful.

It might be preferable to just sample the colorbar; find all the
colors in the image; calculate how close the image colors are to the
colorbar colors (in HSV?); then assign corresponding values to the
image colors if they are closer to the nearest colorbar color than
some threshold. This is similar to what was originally proposed by
Jeremy Bailin, although not as elegant as the later fitting methods
described in this thread. There is even the
IDLgrPalette::NearestColor method that will find the nearest color for
you if supplied with both the sampled colorbar and the image color to
match, although I don’t know exactly how it finds the nearest color.

Thanks all.

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