Definition
Plain language
A score for how visually similar two images are, judging structure rather than exact pixels.
As stated in the literature
Structural Similarity Index Measure, a perceptual image-quality metric comparing luminance, contrast, and structure; paired with PSNR as an acceptance threshold for generated images.
Why it matters: By focusing on perceived structure rather than exact pixels, it better matches how people judge image quality, serving as an acceptance threshold.
For example, it judges two photos as similar if their structures and contrasts line up, even when individual pixel values differ slightly.
Heard on the show
“The Show-o2 checker accepts images with PSNR above thirty-five decibels and SSIM above point-nine-eight against the baseline.”Episode 027 — When AI Agents Build the Serving Stack: A Bet on Bespoke Infrastructure