Use of YCrCb color space model in ImageJ to differenciate weeds from crops

I am currently working on ImageJ to determine soil coverage by crop and soil coverage by weeds (and to know how much soil in uncovered).

Considering the bibliography (,
I wanted to use the YCrCb color space model with the Cg components.
I already have download the converter from RGB pictures to YCrCb.
At this point I don’t know how can I go further into my analysis to calculate the area of crops and the area of weeds.

Thank you so much for your help !


PS : this image is one of the image I would like to analyse

Bibliography says : “Cg component can be obtained by matrix trans-formations fromRGBcolor space model. Thus, conversion algo-rithm was simpler and calculation was smaller. The conversionformula is as shown in formula(1) Ghazali et al., 2012.” Tang et al., 2016.
I have a matrice but how can I translate that for image J ?