On Tue, 5 Jan 2021 at 00:18, Tanya Riseman <[email protected]> wrote:
> You are supposed to use the tone equalizer module instead of the zone system > module now. According to the manual, zone system is deprecated. > > The zone system is pretty easy for beginners to pick up. > The tone equalizer is much harder to get up to speed with. It lacks a 2D zone > image. > It only has crosshairs that correspond to a hard to understand contrast mask, > not the zone. The zone system was just one of the ways to define a tone curve. The resulting curve was applied at the pixel level (all pixels with a given value were affected the same way, without taking their surroundings into account). To replicate the same behaviour, you don't need the mask: select the 'simple tone curve' preset from the tone equalizer (this disables masking), switch to the 'advanced' tab, hover over the image, and start scrolling up and down to adjust brightness. That's pretty simple to use, I think. You could also use one of the other curves, too. It's important to understand what the tone EQ mask achieves. By using the mask, you establish the *average brightness level of each part* of the image, and then raise or lower the brightness of *each part* (it's still not completely local: all areas of the same average brightness will be treated the same way -- you can apply further masks, just like for any other module, to change that). This difference is very important: it allows you to keep local contrast. That is, if in a relatively dark region you have a few brighter details (say, in the midtones), raising the brightness of the dark *pixels* (whether using the zone system, the tone curve, RGB curve, base curve, or tone EQ without masking) the midtone pixels will be less affected (or not at all): the brightness difference decreases, contrast is lost in details. With the mask, all pixels in that region are affected the same way: the midtone pixels in a dark area will be brightened along with their surroundings, and contrast is kept. If you use the tone EQ to compress the dynamic range (global contrast), the same midtone pixels, in the middle of a bright area, could be darkened, maintaining local contrast intact; with traditional curves (and the zone system module) the midtone pixels would be either brightened or darkened everywhere the same way. The 'zone map' of the zone system module is actually misleading, as it implies the module really divides the image into areas based on brightness, and then acts on the areas, but it does not actually do that. Kofa ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to [email protected]
