This is a good introduction to local contrast: http://www.cambridgeincolour.com/tutorials/local-contrast-enhancement.htm
Everything from this point on: this is my understanding, and could easily be wrong - probably is, in parts. I think coarseness of the local contrast is analogous to the radius of USM described above. Contrast and detail are like amount, although I don't know the exact inner workings. I usually use the equalizer. It works like an audio equalizer. Lower frequencies provide a low-resolution view of your image; boosting them will increase local contrast (such as a dark cup will stand out more when placed on a white table cloth). High frequencies are the details; boosting them will sharpen the image (the individual pixels that form e.g. the edge between a stand of fiber in the cloth or a fissure in the cup will stand apart more from their neighbours). Playing with frequencies in between will let you smooth skin without eliminating all detail like pores). Local contrast, sharpen and equalizer always take into consideration the surrounding pixels when determining how a given pixel should be modified. Contrast, tone curve, base curve, zone system just check the values of an individual pixel, without looking at its neighbours. Base curve is in "RGB", in camera colour space, unless I'm mistaken. Each channel is mapped individually, thus colour is affected: applying a steep curve to a pixel with high red value and low blue will increase red and decrease blue, making the colour more saturated (and shifting its hue?). Tone curve operates in Lab, you adjust the L channel and darktable auto-adjusts colour (a and b), unless you tell it you want to do it yourself. Contrast applies a kind of centered tone curve. The zone system tool is also like the tone curve, as far as I know. I haven't had time to watch the videos in the open source photography course, but I guess it covers most of these. Maybe Robert Hutton and others have some useful and free videos, too. Kofa On 19 Sep 2016 16:22, <darkta...@911networks.com> wrote: On Mon, 19 Sep 2016 06:33:31 +0200 KOVÁCS István <k...@kovacs-telekes.org> wrote: >Please read the manual. I did: Much more versatility for contrast and brightness adjustment is offered by the tone curve, levels, and zone system modules and Likewise you may adjust color saturation in a more detailed way with the tone curve, color contrast, and color zones modules and contrast This slider adjusts the image's contrast. brightness This slider adjusts the image's brightness. saturation This slider adjusts the color saturation. Is there some table that compares the various multiple ways of doing the same thing in DT? -- sknahT vyS ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
