This tool computes (dis)similarity between two or more PNG &/or JPEG images using an algorithm approximating human vision. Comparison is done using a variant of the SSIM algorithm.
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.
Please be mindful about color profiles in the images. Different profiles, or lack of support for profiles in other tools, can make images appear different even when the pixels are the same.
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 the DSSIM version. The scale has changed between versions.
The version is printed when you run dssim -h
.
Download from releases page. It's also available in Mac Homebrew and Ubuntu Snaps.
You'll need Rust 1.52 or later. Clone the repo and run:
cargo build --release
Will give you ./target/release/dssim
.
Scores for version 3.0 measured against TID2013 database:
TID2013 | Spearman | Kendall ---------|----------|-------- Noise | -0.9392 | -0.7789 Actual | -0.9448 | -0.7913 Simple | -0.9499 | -0.8082 Exotic | -0.8436 | -0.6574 New | -0.8717 | -0.6963 Color | -0.8789 | -0.7032 Full | -0.8711 | -0.6984
DSSIM is dual-licensed under AGPL or commercial license.
For compatibility with single-threaded WASM runtimes, disable the threads
Cargo feature. It's enabled by default, so to disable it, disable default features:
toml
dssim-core = { version = "3.2", default-features = false }