Posted by
Michael Schmid on
Dec 20, 2010; 2:13pm
URL: http://imagej.273.s1.nabble.com/Re-Assessing-bird-colouration-tp3686131p3686136.html
Hi,
just one remark that seems to have been omitted in the discussion so
far:
When using a digital camera instead of spectra, you must make sure
that the images are taken under equal illumination conditions.
Adjusting white balance will be not enough when using different light
sources such as sunlight, light bulbs or fluorescent lamps (the
latter is probably the worst).
The problem of color metamerism mentioned by Gabriel not only implies
that different spectral distributions are perceived as the same color
(this might be tolerated if there are only a few different pigments
or is interference is responsible for the colors).
Even more mimportant, the same actual color will give different R:B:G
ratios when the spectral distribution of the lamp is changed.
Michael
________________________________________________________________
On 20 Dec 2010, at 09:14, Ross Ahmed wrote:
> Many thanks for all the comments so far.
>
>
>
> I'll just quickly summarise the background to my query. In late
> November, a
> Hoopoe was found dead in Durham, UK and is now stored at the Discovery
> Museum in Newcastle, UK. To my eyes, the dark colouration of the
> orange on
> the bird suggests it may belong to the subspecies saturata (which
> originates
> from Asia), as opposed to the subspecies epops (which originates from
> Europe). As concluded by Ericson, a key difference between these
> subspecies
> is the colouration of the orange. A photo of the bird can be found
> here:
>
http://www.flickr.com/photos/31121749@N06/5276824748/>
>
>
> If it is possible to produce equivalent results as Ericson, this
> would help
> in deciding which subspecies the bird belongs to (and therefore
> whether it
> may have originated from Asia or Europe).
>
>
>
> So could anybody provide a step-by-step method, which would produce
> results
> comparable with those of Ericson, for photographing the bird (my
> camera is a
> Canon 40D) and analysing the photos in Image J (or any other program)?
> Robert Dougherty in particular hinted that this may be possible.
>
>
>
> Thanks again
>
>
>
> Ross
>