Legacy ImageMagick Discussions Archive

Hi all,

We use the signature property to identify images in our product - using Magick::Image::signature or as shown by the identify.exe tool.
We were previously using version 5.3 and have now upgraded to version 6.5 and have found that the signatures returned from each image are different.
As we have large databases of signatures that we use to detect images this has caused big problems for us as all the signatures are now useless witht the new version.

Can anyone tell me when and why the signatures changed, and whether they are likely to do so again in future ?

I tried looking for answers to this problem on the boards but didnt find any, so sorry if its going over old ground.

Any help would be greatly appreciated.


Thanks,

Paul

Our goal in the ImageMagick 6 series was to make the image signature invariant across all quantum bit depths of ImageMagick (i.e. 8, 16, and 32-bits per pixel component). Previously the same image at Q8 and Q16 would produce different signatures which we consider a design flaw. It is *very* unlikely the algorithm will change again. If it did, we would default to the current signature method and require an option to use any new signature method we introduce.

Thank you so much for your quick response

Paul