Your second edit nails it. I thought the brightness in HSB was equivalent to value, which is what I built my second graphic around. If you use my shitty grayscale converter (Desaturate in Photoshop) they all come out to the same gray, so I thought I had it right.

Using Black & White gets me results much closer to what you've made.

Thanks for criticizing my graphics and putting up improved ones. (The second one isn't working, but I understand your point about the green – again, Desaturate convinced me they were all the same value.)

It's really hard to isolate and demonstrate one property of color at a time.