deflickering

Deflickering is the process of reducing or removing flicker artifacts in video sequences and time-lapse imagery by compensating for periodic brightness variations. Flicker can manifest as frame-to-frame brightness shifts, banding, or strobing, and it can degrade visual quality and hinder automated analysis.

Causes of flicker include lighting that fluctuates with mains electricity (such as fluorescent or some LED sources), light sources driven by PWM dimming, and camera effects like rolling shutters or mismatches between frame rate and light flicker. Exposure settings, white balance, and rapid motion can also interact with flicker to produce artifacts, especially in long sequences or high-contrast scenes.

Deflickering techniques fall into post-processing and in-camera approaches. Common post-processing methods include temporal normalization across frames, adaptive filtering to smooth luminance variations while preserving detail, and frequency-domain or multi-frame averaging approaches that remove periodic components without removing genuine motion. Some methods rely on estimating the flicker frequency and phase to remove the corresponding signal component, while others use scene-aware adjustments to avoid color shifts or noise amplification. In-camera options may include anti-flicker modes, higher shutter speeds, or electronic shutter settings designed to minimize frame-to-frame luminance changes.

Applications span video production, time-lapse photography, surveillance, and scientific imaging where stable luminance is important. While deflickering can improve perceptual quality and analysis accuracy, aggressive processing can introduce artifacts or blur fine detail, so methods are often chosen to balance flicker reduction with image integrity.