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How to convert RGB to CIE lab

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  • 2 years later...

Thank you so much.
Can you recommend me a good place to find basic tutorials for vision. I have just started using this 3 days ago for my and I couldn´t figure out how to modify this for my program.
I need to automatically take pictures every 10 minutes with a user defined exposure and convert them from RGB to LAB.
Can you please help me out with this?

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Hello Greg

Sorry again but in this one does the L out a out and b out
what are they doing? are they storing the image somewhere. 
usually when I right click and click on help they give a description but there was nothing on this one.


It does the work fine though when I connect it to an image display. Is there a way to get pixel by pixel value of luminance and store it in a text file?

Edited by Nikhil Ratna Shakya
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There appear to be a couple of reasons they don't match.


1. LabVIEW returns L in the range 0-255, whereas it is more common to use 0-100 as EasyRGB does.

2. It looks as though that website does a Gamma correction when converting RGB to XYZ (see the formulas - notice it raises to the power of 2.4) whereas LabVIEW does it without correction.  That will make a huge difference, and it's non-linear as well.


You can always code up the formulas from the EasyRGB website if you want to use the same!  But without a good understanding of color spaces and the acquisition of your particular images, I'm not sure you're really any better off.


The formulae LabVIEW uses are hidden at the bottom of the Color Pattern Matching help page - took ages to find them!

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