Gradierungskurve

Gradierungskurve is a German term that translates to "tone curve" or "gradational curve" in English. It is a fundamental concept in image processing and digital photography, used to adjust the tonal range and contrast of an image. Essentially, a gradierungskurve is a graphical representation of how brightness values in an image are mapped from their original input to their new output.

The curve is typically plotted on a two-dimensional graph, with the horizontal axis representing the original brightness levels (input) and the vertical axis representing the adjusted brightness levels (output). The diagonal line from the bottom left to the top right corner represents a linear mapping, meaning no change in brightness.

By manipulating the shape of the gradierungskurve, users can selectively alter the brightness of different tonal ranges within an image. For instance, an upward curve in a specific section will brighten that tonal range, while a downward curve will darken it. Steep slopes indicate a greater change in brightness for a small change in input, leading to increased contrast. Conversely, flatter slopes result in less contrast.

Common adjustments include increasing overall contrast by creating an "S" shape (brightening highlights and darkening shadows), reducing contrast by flattening the curve, or selectively adjusting midtones, highlights, or shadows independently. Photographers and graphic designers use gradierungskurven extensively in post-processing software like Adobe Photoshop and Lightroom to achieve desired aesthetic effects, correct exposure issues, and enhance image detail.