Gradationskurven

Gradationskurven, often translated as tone curves or gamma curves, are a fundamental tool in image editing and digital photography used to adjust the tonal range and contrast of an image. They graphically represent the relationship between the original brightness values of an image and the new brightness values after adjustment. The horizontal axis typically represents the input (original) brightness, ranging from black (0) on the left to white (255 in an 8-bit image) on the right. The vertical axis represents the output (adjusted) brightness.

A straight diagonal line from the bottom-left corner to the top-right corner indicates no change in brightness; the image's tones remain as they were. By manipulating this line, users can alter the image's contrast and brightness. Raising a portion of the curve above the diagonal line brightens those tonal values, while lowering it darkens them. A steeper slope in a particular section of the curve signifies increased contrast in that tonal range, whereas a flatter slope indicates reduced contrast.

Gradationskurven are particularly powerful because they allow for precise control over specific tonal ranges, unlike simpler brightness or contrast adjustments that affect the entire image uniformly. For example, a photographer might use a gradationskurve to selectively brighten shadows without blowing out highlights, or to increase mid-tone contrast for a more dramatic effect. Understanding and utilizing gradationskurven is a key skill for achieving professional-looking image results.