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?".
What do you mean by "join"? You can append the images, if you want. "-layers merge" will put the cropped images back where they came from, provided you still have the canvas data.