chromasignalen

Chromasignalen are the color information components of a video signal that carry hue and saturation, while the luminance, or brightness, is transmitted separately. By separating color from brightness, video systems can compress and process data more efficiently without sacrificing perceived image quality.

In common color encoding schemes used in video, chroma is represented by two channels: Cb and Cr (also known as U and V in some formats), or as color-difference signals relative to luminance. The luma signal is designated Y. The color differences are derived from RGB values so that Y reflects brightness and Cb/Cr encode how blue and red differ from luminance, enabling reconstruction of color when combined.

In analog television, chromasignalen are modulated onto a subcarrier and added to the luminance signal. Different standards use different subcarrier frequencies, for example NTSC typically uses a chroma subcarrier around 3.58 MHz, while PAL uses around 4.43 MHz, with encoding schemes that maintain hue information despite timing and phase variations.

In digital video, YCbCr (or YUVW) is used and chroma can be subsampled to save bandwidth. Common schemes include 4:2:2 (half horizontal chroma resolution), 4:2:0 (quarter chroma resolution, widely used in video compression and streaming), and 4:4:4 (no chroma subsampling). The color information can be converted to and from RGB for processing, storage, and display.

Chromasignalen are fundamental to color reproduction in broadcasting, video storage, and digital imaging. Subsampling and color space conversions aim to balance image quality with bandwidth and storage constraints, while avoiding artifacts such as color bleeding or misalignment.