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NI MAQ Vision Color Matching with extremely close hues

I am working on developing a vision system which detects differences in color for a product testing station. Three colors that I am trying to identify are extremely similar.

-The IMAQ ColorMatch tool identifies them as identical and varying the match saturation threshold does not help.  

-The color classification tool which is integrated into the NI Vision Assistant is inconstant on matching the correct classification to each color and will vary its match correlation number based on which ROI is selected.

-The only consistent way to identify what the color that I have found is via the histograms which are visually different.


I am wondering if there are any VIs out which compare color histograms and provide a match number or match percentage to a template histogram. The match number is important since there needs to be an acceptable range of variation.


Attached are the 3 captured colors and their corresponding histograms. Note, I am only showing the green histogram since it is the only important one.

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Hi sstats,

Unfortunately, I haven’t seen any already built VI within LabVEW for that type of operations. I did find some other people providing examples for such operations. Please consider the next 2 resources as a a reference:



And G


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Thanks AGJ, i ended up writing a custom histogram matching VI for my aplication since i didnt want to get into dealing with C++. I aprecaite the references though!


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