The commands in the modify the colorization of pixels. Many common photo editing adjustments are available and all have associated keyboard shortcuts.
This example image will be used to illustrate the various adjustments:
Auto-Level is used to equalize the range of colors in an image.
The adjustment attempts to bring images which are under exposed or over exposed (overly dark or bright) back within normal range. Auto-Level has no configurable options and does not display a dialog.
The Auto-Level adjustment is equivalent to using the Levels adjustment and clicking the "Auto" button.
After applying Auto-Level.
Black & White
This adjustment desaturates an image, removing all color information and rendering the image in grayscale. The resultant image will be reinterpreted in black, white & shades of gray.
Image desaturated with Black & White.
Brightness / Contrast
This adjustment is used to make an image brighter or darker (Brightness), or to make colors stand out more or less from other colors (Contrast).
Both increased brightness and contrast
The Curves adjustment is used to adjust the luminosity and/or RGB (Red, Green & Blue) color curves of an image. This powerful adjustment is covered in detail in the Curves section.
This adjustment is primarily used to change the saturation, or vividness, of the colors in an image. The gamut of Hues can be rotated to render the image in a different palette while maintaining the same levels of contrast. The adjustment also allows the modification of the images Lightness, which is similar to the Brightness adjustment (see above).
Modified image showing Hue rotated to 88 and Saturation of 158.
This adjustment is very similar to a photographic negative. Colors are swapped for the hue found on the opposite side of the color wheel. Black become White and vice versa for example. Applying the adjustment a second time restores the original image coloration.
Image with inverted colors.
This complex adjustment is used to adjust the color range and gamma index of an image. A detailed discussion of this adjustment can be found in the Levels section.
This adjustment reduces the number of available color values that each pixel can use. Normally, each of the RGB (Red, Green & Blue) color channels has 256 possible values (0 through 255). This adjustment limits the range from as few as 2 to a maximum of 64 possible values. The effect gives an image a "posterized" or even a retro or "faux dithered" look.
This adjustment mimics an aged photograph by rendering the image in black & white, and adding a sepia tone. This can be used to give images an "aged" look.
Image after the "Sepia" Adjustment