cyvips

An experiment in making a full Python binding for libvips using Cython.

Instructions

python3 setup.py build_ext --inplace
python3 test.py

Debugging

cython --gdb src/cyvips.pyx
python3 setup.py build_ext --inplace --debug
cygdb . -- -ex r --args python3 test.py

Benchmarks

# Disable the CPU frequency scaling while running the benchmark
sudo cpupower frequency-set --governor performance

# tune your system to run stable benchmarks
python3 -m pyperf system tune

python3 perf/operation-call-pyvips.py -o operation-call-pyvips.json
python3 -m pyperf stats operation-call-pyvips.json

python3 perf/operation-call-cyvips.py -o operation-call-cyvips.json
python3 -m pyperf stats operation-call-cyvips.json

# command to test if the difference is significant
python3 -m pyperf compare_to operation-call-pyvips.json operation-call-cyvips.json --table

# Prepare test-images
mkdir tmp/
vips colourspace perf/images/sample2.v tmp/t1.v srgb
vips replicate tmp/t1.v tmp/t2.v 20 15
vips extract_area tmp/t2.v tmp/x.tif[tile] 0 0 5000 5000
vips copy tmp/x.tif tmp/x.jpg
vipsheader tmp/x.jpg

python3 perf/pyvips-bench.py -o pyvips-bench.json
python3 -m pyperf stats pyvips-bench.json

python3 perf/cyvips-bench.py -o cyvips-bench.json
python3 -m pyperf stats cyvips-bench.json

python3 -m pyperf compare_to pyvips-bench.json cyvips-bench.json --table

# After benchmarking you can go back to the more conservative option
sudo cpupower frequency-set --governor powersave

Benchmark	operation-call-pyvips	operation-call-cyvips
Operation.call	70.7 us	18.5 us: 3.83x faster (-74%)

Benchmark	pyvips-bench	cyvips-bench
vips bench	190 ms	189 ms: 1.01x faster (-1%)

Conclusion

In terms of performance, there's no significant difference between pyvips (using CFFI API mode) and cyvips (using Cython).