Fast SSIMULACRA2 Implementation in Zig

fssimu2 Fast SSIMULACRA2 derivative implementation in Zig. Usage fssimu2 | [version] usage: fssimu2 [options] < reference > < distorted > options: --json output result as json --err-map < out > save error map to .png/.tga -h, --help show this help -v, --version show version information sRGB PNG, PAM, JPEG, WebP, or AVIF input expected Example output: $ ./ssimu2 ref.png dst.png 79.83781132 Performance Performance tested on the Intel Core i7 13700k using a 3840x2160 test image. The numbers indicate that this implementation is up to 23% faster and uses ~40% less memory compared to the reference implementation. poop "ssimulacra2 medium.png dst.png" "./ssimu2 medium.png dst.png" Benchmark 1 (7 runs): ssimulacra2 medium.png dst.png measurement mean ± σ min … max outliers delta wall_time 809ms ± 46.8ms 760ms … 857ms 0 ( 0%) 0% peak_rss 1.34GB ± 1.51MB 1.34GB … 1.34GB 0 ( 0%) 0% cpu_cycles 3.90G ± 243M 3.65G … 4.15G 0 ( 0%) 0% instructions 9.33G ± 3.00M 9.32G … 9.33G 1 (14%) 0% cache_references 118M ± 1.33M 116M … 119M 0 ( 0%) 0% cache_misses 60.0M ± 3.00M 57.0M … 63.4M 0 ( 0%) 0% branch_misses 16.6M ± 101K 16.5M … 16.8M 0 ( 0%) 0% Benchmark 2 (9 runs): ./ssimu2 medium.png dst.png measurement mean ± σ min … max outliers delta wall_time 618ms ± 10.4ms 603ms … 631ms 0 ( 0%) ⚡- 23.6% ± 4.2% peak_rss 817MB ± 118KB 816MB … 817MB 0 ( 0%) ⚡- 39.1% ± 0.1% cpu_cycles 3.05G ± 45.1M 2.99G … 3.10G 0 ( 0%) ⚡- 21.7% ± 4.5% instructions 6.17G ± 24.8M 6.11G … 6.18G 3 (33%) ⚡- 33.8% ± 0.2% cache_references 74.7M ± 13.7K 74.7M … 74.7M 1 (11%) ⚡- 36.6% ± 0.8% cache_misses 34.9M ± 686K 34.1M … 35.8M 0 ( 0%) ⚡- 41.9% ± 3.7% branch_misses 11.4M ± 138K 11.0M … 11.5M 1 (11%) ⚡- 31.2% ± 0.8% Conformance to the reference SSIMULACRA2 implementation can be tested with validate.py by supplying the ssimu2 binary. validate.py requires uv and libjxl . validate.py --custom ~ /git-cloning/fssimu2/zig-out/bin/ssimu2 ~ /git-cloning/gb82-image-set/png/ * Output on the gb82 image set invoking the above command: SAMPLES: 75 LEVELS: 1.0 2.0 4.0 == custom vs ref == pairs: 75 ref mean: 77.5116 std: 10.6899 custom mean: 76.9932 std: 11.1606 mean diff (other - ref): -0.518406 diff stddev: 0.541576 diff stderr: 0.0625359 percentage error (mean diff / ref mean): 0.669% max absolute error: 1.9165 == correlation == PCC (Pearson): 0.999700 SRCC (Spearman): 0.999403 KRCC (Kendall): 0.987748 Error Map The ssimu2 binary optionally allows specifying an error map output image as either an uncompressed .tga (Targa) or PNG. Error maps use the Turbo color map for error visualization, which emphasizes visually obvious errors well. An example output is provided here, generated using ./ssimu2 --err-map map.png ref.png dst_bad.png which resulted in a score of 49.37005220 . Compilation Compilation requires: Run zig build --release=fast , and the binary will emit to zig-out/bin/ssimu2 . The library will emit to zig-out/lib/libssimu2.so (or .dylib on macOS, .dll on Windows) and the include will be moved to zig-out/include/ssimu2.h . C ABI fssimu2 provides a C-compatible ABI with the ssimu2.h include file. Header The exposed functionality is as follows: // Compute a SSIMULACRA2 score // The caller must ensure that the reference and distorted buffers // are at least (width * height * channels) bytes long. If not, // could lead to UB in ReleaseFast int ssimulacra2_score ( const uint8_t * reference , const uint8_t * distorted , const unsigned width , const unsigned height , const unsigned channels , const double * out_score ); Example Usage An example C program is provided in the c_abi_example/ directory, featuring a simple PAM decoder and SSIMULACRA2 computation. See the test.c file for usage. In order to build the test example, enter the c_abi_example/ dir and run: cc test.c pam_dec.c -I../zig-out/include -L../zig-out/lib -lssimu2 -o test # Set library path for Linux LD_LIBRARY_PATH=../zig-out/lib ./test ref.pam dst.pam # Set library path for macOS DYLD_LIBRARY_PATH=../zig-out/lib ./test ref.pam dst.pam When fssimu2 is properly installed system-wide, the library path specifier isn't needed. License This project is under the Apache 2.0 license. More details in LICENSE.