Kontrasztkorrekció

Kontrasztkorrekció, in image processing and photography, refers to the adjustment of the difference in luminance or color that makes an object distinguishable from other objects and the background. Essentially, it manipulates the range of tones within an image to make it appear more or less dramatic, clearer, or richer.

There are several ways to achieve contrast correction. One common method involves adjusting the image's histogram. The histogram displays the distribution of pixel intensities in an image. By stretching or compressing this histogram, one can alter the overall contrast. For example, stretching the histogram to occupy a wider range of the available tonal values will increase contrast, making the dark areas darker and the bright areas brighter. Conversely, compressing the histogram will reduce contrast, leading to a flatter or more muted appearance.

Another approach is to use specific algorithms that analyze local image regions. These methods, such as adaptive histogram equalization, can enhance contrast in specific areas of an image without over-amplifying noise or blowing out highlights in others. This is particularly useful for images with varying lighting conditions.

Contrast correction can be applied to both grayscale and color images. In color images, contrast can be adjusted across individual color channels (red, green, blue) or by manipulating the luminance component of a color space. The goal is typically to improve the visual appeal, clarity, or impact of the image, helping to draw attention to details or create a specific mood. However, excessive contrast correction can lead to the loss of detail in very dark or very bright areas, a phenomenon known as "clipping."