Re: Filtering certain color range

Posted by Michael Schmid on May 14, 2008; 2:40pm
URL: http://imagej.273.s1.nabble.com/Filtering-certain-color-range-tp3696226p3696228.html

Hi,

This looks like a problem for Principal Component Analysis (PCA)
to me - you will find such plugins by searching the web for
"ImageJ plugin pca" or
"ImageJ plugin Principal-Component-Analysis".

PCA will automatically select a suitable way to segment the
color space.

To reduce image noise, you can try preprocessing by an
edge-conserving smoothing algorithm:
Anisotropic Diffusion or Sigma filter, on the ImageJ web site,
   http://rsb.info.nih.gov/ij/plugins/
Thresholded Blur or Surface Blur on the Documentation wiki
   http://imagejdocu.tudor.lu/imagej-documentation-wiki/plugins

Michael
________________________________________________________________

On 14 May 2008, at 14:25, Carl Sebeny wrote:

> 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: [hidden email]
>
>
> -----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.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.
> --
> View this message in context: http://www.nabble.com/Filtering- 
> certain-color-range-tp17182225p17182225.html
> Sent from the ImageJ mailing list archive at Nabble.com.