Oh, ok. I thought those were paper curves in the diagram. Sorry about that.
Can someone let me know where this is in Haist? I didn't remember anything about tone reproduction being in the sensitometry section at the end of Volume 1 (the Sensitometry section is excellent, by the way, and details not only ISO test methods but also addresses some of the problems involved in both sensitometry and image evaluation). But there is nothing really about tone reproduction.
Is it somewhere in Volume 2? I haven't had a chance to check.