Re: Assessing bird colouration

Posted by dscho on Dec 20, 2010; 12:30am
URL: http://imagej.273.s1.nabble.com/Assessing-bird-colouration-tp3686141p3686146.html

Hi,

On Sun, 19 Dec 2010, Robert Dougherty wrote:

> Ericson seems to have based his analysis on a 3-D color space "designed
> to fit the human perception of color hues."  Since the RGB / HSB color
> space used in ImageJ is also presumably oriented around human
> perception, is it possible that an RGB image might be sufficient in this
> particular case?

First of all, there are so many different definitions of RGB out there
that you cannot speak of a single RGB space.

> I'm suggesting that if the illumination and the RBG filters in the
> camera and everything else were lined up correctly, that it might be
> possible to get equivalent results.  Even if the color values did not
> exactly match Ericon's, they still might be rich enough to classify
> Hoopoes by sex and subspecies.

You can actually convert from sRGB (or any well-defined RGB) to CIELAB.
There is even a weakly-tested version of this algorithm (expecting the
current RGB image to be in sRGB, really) in Fiji's Image>Color menu.

Whether that is enough to reproduce the results of the paper remains to be
tested, though (the paper is really funny in that they go out of their way
to record a full-blown spectrogram, but then they reduce it to CIELAB
again...).

Ciao,
Johannes