I just ran qoibench on the photos they used[1] and QOI does indeed fair pretty badly with a compression ratio of 71.1% vs. 49.3% for PNG.
The photos in the QOI benchmark suite[2] somehow compress a lot better (e.g. photo_kodak/, photo_tecnick/ and photo_wikipedia/). I guess it's the film grain with the high resolution photos used in [1].
I just ran qoibench on the photos they used[1] and QOI does indeed fair pretty badly with a compression ratio of 71.1% vs. 49.3% for PNG.
The photos in the QOI benchmark suite[2] somehow compress a lot better (e.g. photo_kodak/, photo_tecnick/ and photo_wikipedia/). I guess it's the film grain with the high resolution photos used in [1].
[1] https://imagecompression.info/test_images/
[2] https://qoiformat.org/benchmark/