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?".
Please clarify. Do you want to resize them to the same size? Or do you just want to resize to make them all smaller? You can use -resize to do the resize and +append to put them size by side. But you will have to loop over your directories to select the pairs of images and then use convert to do the processing.
It would help if you clarified further.
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Please, always provide your IM version and platform when asking questions, since syntax may differ.
Also provide your exact command line and your images, if possible.