Compare Images (PSNR SSIM)

@opencv1 VersionCalculate

Compares a candidate Image against a reference Image and emits full-reference quality metrics, either as a {psnr: Double, ssim: Double, mse: Double} record or as [Analytics.Metric].

How it fits

Typical backends

Compare two image sources and log the quality metrics.

Compare an image against a denoised version of itself to measure how much an enhancement step changed it.

Caveats

I/O contractThe two inputs are aligned pairwise; the metrics measure pixel-level agreement between a candidate and its reference, not perceptual or semantic similarity.
I/O contractA size mismatch is reconciled by resizing the candidate to the reference geometry before scoring, so a mismatched pair never stops the stream; feed images that already share dimensions for the truest per-pixel comparison.
AccuracyIdentical inputs report a maximal PSNR sentinel rather than infinity, so a perfect-match score is a capped value, not an unbounded one.
LimitationThe metrics are full-reference and require a known good reference image; use a single-image quality estimator when no reference is available.

Versions

4b9e359alatestdefault
Automated release
6/29/2026