I think they mean the absorption artificially increases the separation of the mean response wavelength for both the red and green cones. Essentially it is reduc

I think they mean the absorption artificially increases the separation of the mean response wavelength for both the red and green cones. Essentially it is reducing the overlap of their spectral response by filtering out the places where they can strongly overlap for the 99% of colorblind people with this type of colorblindess[0]. [0] 99% number is from the article. I have no idea if that's accurate or not. Edit: Clarifying wording, spelling