Deforum's anti-blur applies an unsharp mask to counteract the progressive blurring that builds during long animations

During Deforum animations, repeated frame-warping and diffusion sampling gradually introduce blur. The anti-blur feature applies an unsharp mask: it computes a Gaussian blur of the current frame, subtracts it from the source to isolate edge/high-frequency information, then adds that back scaled by amount_schedule. threshold_schedule sets the minimum pixel-value difference that counts as an ‘edge’ to sharpen, so smooth tonal areas (sky, skin, water) can be protected from blemishes; kernel_schedule sets the Gaussian kernel dimensions and sigma_schedule the blur width per pixel. All three take effect only when amount_schedule > 0.

Examples

amount_schedule 0:(0.5) — moderate sharpening. threshold_schedule 0:(0.01) — sharpen most edges. threshold_schedule 0:(0.04) — only sharpen strong edges, protecting skin tones or sky gradients.

Assessment

Explain why Deforum animations become progressively blurrier over many frames, and describe how setting threshold_schedule protects smooth areas like sky from anti-blur artefacts.