This tool computes (dis)similarity between two or more PNG images using an algorithm approximating human vision.
Comparison is done using the SSIM algorithm at multiple weighed resolutions.
The value returned is 1/SSIM-1, where 0 means identical image, and >0 (unbounded) is amount of difference. Values are not directly comparable with other tools. See below on interpreting the values.
dssim file-original.png file-modified.png
Will output something like "0.02341" (smaller is better) followed by a filename.
You can supply multiple filenames to compare them all with the first file:
dssim file.png modified1.png modified2.png modified3.png
You can save an image visualising the difference between the files:
dssim -o difference.png file.png file-modified.png
It's also usable as a library.
The amount of difference goes from 0 to infinity. It's not a percentage.
If you're comparing two different image compression codecs, then ensure you either:
More about benchmarking image compression.
When you quote results, please include DSSIM version, since the scale has changed between versions.
The version is printed when you run
You need Rust
cargo build --release
Will give you
Scores for version 2.9 measured against TID2013 database:
TID2013 Category | Spearman correlation --- | --- Noise | -0.930 Actual | -0.937 Simple | -0.945 Exotic | -0.844 New | -0.800 Color | -0.808 Full | -0.860
DSSIM is dual-licensed under AGPL or commercial license.
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