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Butteraugli – a tool for measuring differences between images

71 points by aorth 10y ago

aorth 10y ago
For reference, I found this tool mentioned in an interesting Medium post: https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3257c#.58x5cckba https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3...
- ibotty 10y ago
  Thank you for linking it! Great post.
- chriswarbo 10y ago
  Slightly off-topic, but it annoys me when Windows filename conventions (e.g. a ".jpg" suffix) are used in lieu of a format's name (e.g. JPEG). Especially when such names are short, well-known, etc. If, for example, I saw an article titled "Parsing HTM with BeautifulSoup", I'd be a little wary of the content.
  - radarsat1 10y ago
    You might have a point in another context, but '.jpg' is so completely ubiquitous that you come off as pointlessly pedantic.
ComputerGuru 10y ago
This couldn't have come at a better time (for me). I'm playing with a genetic programming library to recreate images from some basic rules and I've been really unhappy with the fitness equality functions I've been able to find. This looks like it may have been made for the job.
tauchunfall 10y ago
Would be interesting how this compares to tools like pixelmatch [1] which basically compares each pixel within YIQ color space using euclidian color distance. [1] https://github.com/mapbox/pixelmatch-cpp https://github.com/mapbox/pixelmatch-cpp
electic 10y ago
How is this better than phashes? I am new to this, would love for someone with expertise to explain what the best way to hash images are.
- ratsbane 10y ago
  phashes compute a hash on one image which you can then compare with the hashes for other images; butteraugli computes the difference between two images. If you're trying to find duplicates among a set of images, phashes will work in O(n log n) time and this will run in O(n^2) time, but with more accurate results.
tveita 10y ago
There is definitely room for better and less gameable quality evaluation functions than PSNR and SSIM, but I would have liked to see at a minimum a description of how the algorithm was designed and a practical evaluation against other similarity metrics. See e.g. the graphs in https://ece.uwaterloo.ca/~z70wang/research/ssimplus/ https://ece.uwaterloo.ca/~z70wang/research/ssimplus/ comparing human assigned scores against different similarity metrics.
- lpaone 10y ago
  Thanks for the link. Very interesting. I agree with you about PSNR and SSIM. There are plenty of times where they do a less than stellar job and a quick eye test makes it obvious. Unfortunately the VPxs and h.26xs of the world tune their internal comparison metrics for these to make their codecs score better on comparison tests. Consequently, this can sometimes lead to less than optimal video quality. If this can be applied generally, work better than PSNR/SSIM and be made to run fast enough, it would be interesting to see if this could be used to improve block matching in video codecs. *Edit grammar.
Florin_Andrei 10y ago
Sounds interesting, but some examples would be nice.

71 points by aorth 10y ago

aorth 10y ago

For reference, I found this tool mentioned in an interesting Medium post: https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3257c#.58x5cckba https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3...

ibotty 10y ago
Thank you for linking it! Great post.
chriswarbo 10y ago
Slightly off-topic, but it annoys me when Windows filename conventions (e.g. a ".jpg" suffix) are used in lieu of a format's name (e.g. JPEG). Especially when such names are short, well-known, etc. If, for example, I saw an article titled "Parsing HTM with BeautifulSoup", I'd be a little wary of the content.
- radarsat1 10y ago
  You might have a point in another context, but '.jpg' is so completely ubiquitous that you come off as pointlessly pedantic.

ComputerGuru 10y ago

This couldn't have come at a better time (for me). I'm playing with a genetic programming library to recreate images from some basic rules and I've been really unhappy with the fitness equality functions I've been able to find. This looks like it may have been made for the job.

tauchunfall 10y ago

Would be interesting how this compares to tools like pixelmatch [1] which basically compares each pixel within YIQ color space using euclidian color distance. [1] https://github.com/mapbox/pixelmatch-cpp https://github.com/mapbox/pixelmatch-cpp

electic 10y ago

How is this better than phashes? I am new to this, would love for someone with expertise to explain what the best way to hash images are.

ratsbane 10y ago
phashes compute a hash on one image which you can then compare with the hashes for other images; butteraugli computes the difference between two images. If you're trying to find duplicates among a set of images, phashes will work in O(n log n) time and this will run in O(n^2) time, but with more accurate results.

tveita 10y ago

There is definitely room for better and less gameable quality evaluation functions than PSNR and SSIM, but I would have liked to see at a minimum a description of how the algorithm was designed and a practical evaluation against other similarity metrics. See e.g. the graphs in https://ece.uwaterloo.ca/~z70wang/research/ssimplus/ https://ece.uwaterloo.ca/~z70wang/research/ssimplus/ comparing human assigned scores against different similarity metrics.

lpaone 10y ago
Thanks for the link. Very interesting. I agree with you about PSNR and SSIM. There are plenty of times where they do a less than stellar job and a quick eye test makes it obvious. Unfortunately the VPxs and h.26xs of the world tune their internal comparison metrics for these to make their codecs score better on comparison tests. Consequently, this can sometimes lead to less than optimal video quality. If this can be applied generally, work better than PSNR/SSIM and be made to run fast enough, it would be interesting to see if this could be used to improve block matching in video codecs. *Edit grammar.

Florin_Andrei 10y ago

Sounds interesting, but some examples would be nice.