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Re: Color thresholding and obtaining Lab values

Posted by Rie Sadohara on May 22, 2018; 11:52pm
URL: http://imagej.273.s1.nabble.com/Color-thresholding-and-obtaining-Lab-values-tp5020700p5020704.html

Dr. Sheffiled,

Thank you for the suggestion. I have already tried it, but it recognizes
numerous small dots (very very tiny compared to the beans) as particles,
and ignores the beans in the image. I do not know why, but it does not work
as I would like it to.

Rie

On 22 May 2018 at 19:15, Joel Sheffield <[hidden email]> wrote:

> How about using Analyze Particles?
>
>
>
> Joel B. Sheffield, Ph.D
> Department of Biology
> Temple University
> Philadelphia, PA 19122
> Voice: 215 204 8839
> e-mail: [hidden email]
> URL:  *https://bio.cst.temple.edu/~jbs/ <https://bio.cst.temple.edu/~jbs/>
> <http://tinyurl.com/khbouft>*
>
> On Tue, May 22, 2018 at 5:13 PM, Rie Sadohara <[hidden email]>
> wrote:
>
> > Hello all,
> >
> > I am trying to get Lab values from images of yellow beans. There are some
> > black and white parts in the image, so I want to remove those parts and
> > measure the yellowness of the bean seeds. Below are the steps I took, but
> > Lab values are calculated from the entire image. Could someone tell me
> how
> > to do it right?
> >
> > 1. Open --> Open my photo, which is an RGB color image.
> > 2. Image --> Adjust --> Color threshold... --> Then set the threshold of
> > L* value to be 71-216 so that the black and white parts will be excluded.
> > --> Select.
> > 3. The yellow parts (of which I want to know the Lab values) are circled
> > with yellow lines now.
> > 4.  Image --> Type --> Lab stack.
> > 5. Analyze --> Measure. for each stack (L, a, and b)
> > 6. The returned Lab values are based on the entire image. It works as
> > though there had been no color thresholding.
> >
> > My understanding is that the parts that are circled with bright yellow
> > lines after color thresholding are the area that are going to be used for
> > Lab measurements? (Please see the attachment. In the image, the yellow
> > parts (my ROI) are segregated correctly, but how can I get Lab values out
> > of this region?)
> >
> > Any advice would be greatly appreciated,
> >
> > Rie
> >
> >
> > --
> > ImageJ mailing list: http://imagej.nih.gov/ij/list.html
> >
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>



--
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*Rie** Sadohara  *
Graduate Research Assistant
Department of Plant, Soil and Microbial Sciences
Michigan State University
Plant and Soil Science Building
1066 Bogue St, Room A364
East Lansing, MI 48824
Email: *[hidden email] <[hidden email]>*
Find delicious bean recipes here:
*https://colorfulhealthfulflavorfulblog.wordpress.com/
<https://colorfulhealthfulflavorfulblog.wordpress.com/>*
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