image degradation; video degradation
Technical term used in computing and digital media to describe loss of quality in images or video, often due to compression, scaling, or transmission errors.
To prevent image degradation, please save it at high resolution.
The video degradation is so severe that I can't tell what's being shown.
画質劣化 is a near-synonym also meaning 'image quality degradation', but 画像劣化 is more specifically about the degradation of the image or video data itself, often in a technical computing context.
Compound of 画像 (image) and 劣化 (degradation, deterioration). The exact historical derivation is uncertain, but the term follows standard Sino-Japanese compounding patterns.