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Re: Color thresholding and obtaining Lab values

Posted by Krs5 on May 24, 2018; 3:59pm
URL: http://imagej.273.s1.nabble.com/Color-thresholding-and-obtaining-Lab-values-tp5020700p5020729.html

Did you do your step 4: >   Image --> Type --> Lab stack?

Kees

-----Original Message-----
From: Rie Sadohara [mailto:[hidden email]]
Sent: 24 May 2018 16:58
To: [hidden email]
Subject: Re: Color thresholding and obtaining Lab values

Dr. Staatman,

Thank you for the suggestion. I was able to add the thresholded area to selection, and it was circled by light blue lines.
However, when I hit Measure, it only gives the area and gray area values, because it is what is checked in the Analyze -> Set Measurements... option.
There is no L, a, b values to be selected in that option. It seems that I need to convert the image to Lab stack then hit Measure (or Plugins -> Stack -> Measure stack) to obtain L, a, and b values. But when the image is converted to Lab stack, the selection is lost, and the L, a, b values are based on the entire image including the portions that I do not want to include.

I guess my question is: Is it possible to convert the color-thresholded selection to a Lab stack, or is there a way to measure L, a, b values without converting the image into Lab stack?

Kind regards,

Rie






On 24 May 2018 at 03:24, Straatman, Kees (Dr.) <[hidden email]> wrote:

> Dear Rie,
>
> To measure only your selection you can use:
> - Edit > Selection > Add to Manager
> - in the ROI Manager menus select More > Multi Measure
> - in the menu presented select "Measure all 3 slices" and deselect
> "One row per slice"
>
> I hope this solves your problem.
>
> Best wishes
>
> Kees
>
>
> Dr Ir K.R. Straatman
> Senior Experimental Officer
> Advanced Imaging Facility
> Centre for Core Biotechnology Services University of Leicester
> www.le.ac.uk/advanced-imaging-facility
>
>
> -----Original Message-----
> From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of
> Rie Sadohara
> Sent: 22 May 2018 22:13
> To: [hidden email]
> Subject: Color thresholding and obtaining Lab values
>
> 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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> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>
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> 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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