image rotation

Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
Posts: 18
Joined: 2018-01-07T13:18:56-07:00
Authentication code: 1152

Re: image rotation

Post by dav1988 » 2018-03-03T20:34:12-07:00

ok thanks now i understand better!
anyway so we can say that it does not exist a way to estabilish if the differences are caused by a rotation or not, right?

Posts: 9868
Joined: 2010-01-23T23:01:33-07:00
Authentication code: 1151
Location: England, UK

Re: image rotation

Post by snibgo » 2018-03-03T21:11:22-07:00

We can look at a differences image and see if the difference can be explained by a rotation. For example, we take one image and find the difference with a small rotation of that image, 0.01 degrees:

Code: Select all

convert rkdgyr.jpg ( +clone -rotate 0.01 +repage ) -gravity Center  -compose Difference -composite -auto-level rdg_rot_diff.png
We can look at rdg_rot_diff.png and see that differences occur at high-contrast object boundaries, eg around the woman, and they are strongest when the boundary is a radial from the centre. This strongly suggests a rotation around the centre.

By contrast, the differences between your original two images are very noisy, and not stronger in any direction.
snibgo's IM pages:

Post Reply