The Adaptive tab sheet controls the adaptive contrast effect. The adaptive contrast effect is not as dramatic as the dynamic contrast effect, but is nice for improving the contrast in textured areas. The Adaptive Contrast effect renders quite fast in a small preview, but needs overproportional longer for large images. Depending on the Radius value and your processor it can take up to several minutes on a 10 Megapixel image. To avoid that you can also try activating the Speedup check box.
The Arrow-Down Button
Clicking on the arrow-down button will display a menu with various local presets. These local presets are useful settings for the controls of the current tab sheet. Each tab sheet has its own arrow-down menu with different presets. Only the "Reset" option is the same. It sets the controls of the tab sheet to their default values.
The Intensity slider is only available in Adaptive Contrast mode. In Expert Mode it is replaced by the Adaptive slider on the Mix tab sheet. The Intensity adjust the intensity of the effect. A slider value of zero means no effect and a slider value of 100 applies the effect at full intensity.
The Radius slider adjusts the size of the details that are emphasized. Low slider values focus on small details in the image whereas high slider values bring out the contrast in large details. The unit of the slider is not pixels, but a percentage of the image size. So the same Radius value will produce the same effect for images of different size.
If the check box at the left of the Radius slider is activated, the radius value varies for each pixel. For example if the Radius slider is set to 4, the actual radius values will lie between 0.5 to 8. Textured image areas will be processed with a lower radius value whereas smooth image areas will be processed with a higher radius value. This usually produces a better look. However, if the Speedup check box is activated, the Radius check box will only double the radius value.
The Speedup check box renders the adaptive contrast effect up to eight times faster on large images, but the effect will be a bit be different. In several cases the effect will be be rougher or of lower quality. The Speedup check box also influences the behaviour of the Radius check box by only doubling the radius value, which results in a less balanced effect. It also makes the Range slider work a bit differently.
At high slider values the Range slider emphasizes larger details and produces a softer look. At lower slider values it makes the effect look more rough and brings out smaller details. A medium slider values is best for avoiding halos or a rough look.
The Boost slider increases the strength of the effect. It is set to a medium value by default. So using lower values will weaken the effect and higher values will increase the effect strength. Activating the check box at the left of the Boost slider will emphasize some edges and highlights.
The Soften slider makes the effect look softer. At high values, it helps to reduce halos, but may produce blown highlights.
The Highlights slider darkens the highlights at higher slider values and brightens them at lower slider values. The Shadows slider brightens the shadows at higher values and darkens them at slider values. Both sliders adjust the highlights and shadows using the adaptive contrast algorithm, so they do not work like the Highlights and Shadows sliders of the dynamic contrast effect.