I agree completely :-). However, as a writer first and photographer second, I sometimes split hairs over terminology. In any case, thanks for the excellent illustration of some important concepts. Paul
> I think our difference on the notion of "overall lightening/ > darkening" is simple: I consider white clip and black clip to be > fixed in such adjustment, where you change the bias of the whole > curve. Fair point, but I'm comfortable with my approach .... I > consider white and black clip to be independent. > > Gamma correction is, however, the relative shape of the slope between > white and black clip points so I differ with your interpretation > there. In that sense, all three of these are gamma corrections of a > sort, but I pick the two-node curve as being a "typical" gamma > correction where the single node corrections are more simplistically > used for overall light/dark. > > All these curves are somewhat exaggerated to show the effect clearly, > of course. If exposure is correct, real adjustments would be > significantly smaller. > > Of course, part of the reason to post the curves and their effects on > a gray gradient as well as a photo is to show what I meant, which I > struggle with in words. So consider them as examples of typical > curves in the Curves Adjustment tool and their effect on image > characteristic, regardless of the adjective used to describe what > kind of correction they represent... ;-) > > (Boris, the pages will be there ... I rarely dump stuff until I run > out of space, and then usually in the "oldest first" order.) > > Godfrey > > On Oct 18, 2005, at 3:47 AM, Paul Stenquist wrote: > > > A good illustration. However, I wouldn't say that 02 and 03 are > > "overall" lightening and darkening curves. The end points remain > > fixed. They are midrange lightening and darkening curves. Because > > the ends are ffixed, the brightest highlights and deepest shadows > > remain unchanged. Rather than calling 04 a "gamma correction > > curve," which cold be anything, I would describe it as a curve > > intended to increase midrange contrast. Once again, the ends are > > fixed. > > On Oct 18, 2005, at 12:04 AM, Boris Liberman wrote: > > > >> Great many thanks... I will try to keep in mind the word "beer" if > >> we get to meet in person. Please don't remove that page from your > >> web site, will you? > >> > >>> - Boris, all is revealed at > >>> http://homepage.mac.com/godders/grayscale20051017/ >
