[R] image color analysis

[Robert Baer]

On 3/13/2013 12:05 AM, ishi soichi wrote:
> I am not sure if I should ask this question in this list. But I'll try.
>
> Currently I am trying to analyze images using EBImage and biOps.
> One of the features that I need to extract from various images is the color
> spectrum, namely, which colors each image consists of.
>
> So, each image hopefully can be converted into some sort of color histogram
> so that color ingredients are easily comparable with each other.
>
> There are so many functionalities that these packages and others provide,
> and I am hoping that someone would give me some guideline for the analysis.
>
> Any suggestion?
Your question is quite general, so I'll make a couple of general 
comments, returning us to R at the end.

You need to read about spectral color systems, for example 
http://www.fourmilab.ch/documents/specrend/. You undoubtedly have used 
filters, whether a Bayer filter typically built into a color camera or 
more specific filters if you have used a monochrome camera to collect 
non-RGB channels.  You need to know what type of transforms might have 
been performed during the storage process.  For example, has the image 
already been transformed to RGB space before storage? In fluorescent 
spectroscopy, for example, it is common to use pseudo-coloring so the 
channels of the stored image may not be directly convertible into 
spectral color without additional information.

R can do all the appropriate matrix algebra once you define the 
specifics of your individual conversion.

Hope this helps,

Rob


>
> Thanks.
>
> ishida
>
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>
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-- 

Robert W. Baer, Ph.D.
Professor of Physiology
Kirksille College of Osteopathic Medicine
A. T. Still University of Health Sciences
Kirksville, MO 63501 USA