As it says, at this point it's getting pretty subjective, and so you'll need a blinded subjective test to really judge which one is better: The improvement i

As it says, at this point it's getting pretty subjective, and so you'll need a blinded subjective test to really judge which one is better: The improvement in quality compared to the previous status update is quite obvious. Daala is now much better than both WebP and JPEG (libjpeg-turbo is the most commonly used JPEG encoder). As for Daala vs BPG/HEVC, the artifacts are obviously different and hard to judge from just four images. Opinions are likely to vary based on the viewer and the input image. At this point, what we'd really need is a full subjective test. Fortunately, this is exactly what is going to take place shortly, as Daala has been submitted as a candidate for the Image Compression Grand Challenge at ICIP 2016. The results should be available in September. In the mean time, you can read the paper we will be presenting. What I generally do is toggle between three images, the original, Daala, and HEVC, and focus on a different area each time. There is always some obvious distortion from the original, so I try to determine for each area I'm focusing on, which one is closer to the original perceptually. It is a subjective process, but if you make this evaluation for each area of the image, count up your judgements over the whole image, do that over multiple images, and have multiple people all do that and combine their results, you can come up with a reasonable evaluation of the quality.