Expand description
SSIMULACRA2 metric calculation.
SSIMULACRA2 is a perceptual image quality metric that correlates well with human visual perception. Higher scores indicate better quality.
Score interpretation:
- 100: Identical
-
90: Imperceptible difference
-
80: Marginal difference
-
70: Subtle difference
-
50: Noticeable difference
- <= 50: Degraded
§Implementation
This module uses fast-ssim2 for SIMD-accelerated SSIMULACRA2 calculation.
It provides significantly better performance than the reference ssimulacra2
implementation while producing identical results.
§ICC Profile Support
When comparing images with embedded ICC profiles, use calculate_ssimulacra2_icc
to ensure accurate color space conversion before comparison. This is critical for:
- XYB JPEGs from jpegli (which embed custom ICC profiles)
- Wide-gamut images (Display P3, Rec.2020)
- Any image with non-sRGB color space
Without proper ICC handling, scores can be off by 1-2 points at high quality levels.
Functions§
- calculate_
ssimulacra2 - Calculate SSIMULACRA2 between two images.
- calculate_
ssimulacra2_ icc - Calculate SSIMULACRA2 with ICC profile support.