http://imagej.273.s1.nabble.com/Color-thresholding-and-obtaining-Lab-values-tp5020700p5020703.html
Joel B. Sheffield, Ph.D
> 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
>
>
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