Blacklevel

Blacklevel is the luminance value that defines the darkest parts of an image in a recording, display, or processing chain. It serves as the baseline from which all other brightness levels are measured. In digital video and photography, the black level often corresponds to a pedestal or offset added to the signal to guarantee a valid minimum code value and to prevent interpretation of noise as true blacks.

In sensor and camera workflows, the black level is influenced by dark current, sensor bias, and analog-to-digital converter offsets. Proper calibration sets the black level so shadow detail is preserved and crushed blacks are avoided. Temperature changes and aging can shift the black point, requiring periodic re-calibration.

Video standards and display systems describe black level in relation to encoded or mapped luminance. Many broadcast and mastering workflows use limited-range video, where 16 represents black and 235 represents white in an 8-bit scale (0–255). Full-range signals use the entire 0–255 span, with 0 as true black. Standards such as Rec. 709 and Rec. 2020, and reference formulas like BT.1886, specify how black level should be handled after gamma correction to maintain consistent shadow rendition across displays.

Practical considerations include ensuring the black level is not set so high that detail is lost in shadows, nor so low that noise becomes visible as apparent detail. Calibration tools, scopes, and waveform monitors are commonly used to set and verify the black level for consistent image quality across devices.

See also: black point, pedestal, gamma, white level, display calibration.