Posted by
Carl Sebeny on
May 14, 2008; 12:25pm
URL: http://imagej.273.s1.nabble.com/Filtering-certain-color-range-tp3696226p3696227.html
Consider the following expression:
(R*R + G*G + B*B) - (R*G + R*B +G*B)
If R, G and B are the red, green and blue intensity levels for a pixel then the expression will be nil for any shade of grey (black thru white) and not nil for non-grey pixels. By coding a routine to compute the above expression for each pixel within an image and counting the occurrences of nil values, one can determine the number of grey and non-grey pixels within an image.
Carl Sebeny
Applied Vision, Inc.
eMail:
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-----Original Message-----
From: ImageJ Interest Group [mailto:
[hidden email]] On Behalf Of rasheed
Sent: Monday, May 12, 2008 10:37 PM
To:
[hidden email]
Subject: Filtering certain color range
Hi there everyone,
I would like to know if it is possible to subtract or filter a certain color
range. I have attached a photograph of a core(acquired while drilling the
hole looking for oil). From the image, three different major features (in
terms of color) can be seen, light brown, dark brown and gray.
http://www.nabble.com/file/p17182225/2010.00-2020.00%2Bm.jpg2010.00-2020.00+m.jpg .
What I would like to do is to know the total height of the sand(light and
dark brown) in the image removing the gray stuff which is shale/clay.
Therefore, if I could filter the gray stuff out, I can then plot a profile,
knowing that the low value(or black) is the shale/clay and the rest is sand.
The problem I have now is, when I plot a gray scale profile, it will not be
possible to differentiate the shale from sand as the shale seem to be
brighter than the dark brown sand.
Any advice on this matter is very much appreciated. Thanks guys/gals.
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