how does the speed compare with opencv? about fast_image_resize HOT 14 OPEN

It would be nice to add a comparison with libvips.

from fast_image_resize.

@negezor I've done first comparison of libvips with fast_image_resize.
I've used libvips v8.12.1 from Ubuntu 22.04 repository.
libvips was tested in single-threaded mode with disabled caches.

from fast_image_resize.

I have not yet done a benchmark to measure the speed of opencv.
I plan to do that after I add multithreading support. Because, as I understand it, opencv already has this feature.

from fast_image_resize.

With threads turned off, the results look like this:

benchmark code: https://github.com/bend-n/imenchmark/blob/main/benches/resizing.rs

from fast_image_resize.

I have found out that OpenCV returns incorrect results if we downscale image with different interpolations. All results, except INTER_AREA, look like INTER_NEAREST. With such results I'll can't make any correct benchmarks.

Image bellow is result of downscaling with different interpolations (result was upscaled x2 for better pixels visibility).

from fast_image_resize.

@Cykooz hoping for it!

from fast_image_resize.

I would also love to see comparison with libvips (not only raw performance, but also peak memory usage)

from fast_image_resize.

@bend-n Thank you for your work.

from fast_image_resize.

@bend-n I have only one note about your opencv benchmark. OpenCV doesn't have Lanczos3 implementation. It has only Lanczos4. Lanczoz4 is more complicated (requires more calculations) than Lanczos3.

from fast_image_resize.

Oh yeah i forgot to rename the field to lanczos.

from fast_image_resize.

re: libvips, i cant seem to be able to get it to work properly.

from fast_image_resize.

Why is that? Is opencv bugged? How is it for upscaling?

from fast_image_resize.

Upscaling looks better. I don't know why downscaling is so bad.

from fast_image_resize.

I've understood the reason. OpenCV uses "convolution" with fixed kernel size (it is essentially just Affine Transformations). In this case, downscaling very big image into very small one looks like a result of nearest "interpolation".

fast_image_resize uses convolution with adaptive kernel size. It requires more computations but makes more beter result.

It seems that only INTER_AREA in OpenCV uses real convolution with Box filter and minimal kernel size 1x1px.

from fast_image_resize.