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Re: Filtering certain color range

Posted by Duane and Julie on May 13, 2008; 10:39am
URL: http://imagej.273.s1.nabble.com/Filtering-certain-color-range-tp3696226p3696234.html

First of all, yes, you can filter a certain color range.

For your particular problem, I converted the image to L*a*b* space and  
then used the a* channel.

The new image is now noticeably bimodal in the center of the histogram  
with some spikes at either end.  I thresholded the image to leave the  
bimodal section and then drew a line for the profile.  It seemed to be  
effective.

If you were to spend more than the 60 seconds I did, you would  
probably get pretty good results.

    duane

On May 12, 2008, at 10:36 PM, rasheed wrote:

> 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.jpg
> 2010.00-2020.00+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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