Isn't it super easy to resize images? I wrote a program to resize images after watching a computerphile video on the subject and it took like ten to twenty minutes to get something that seems functionally identical to "real" resizing. If you can read your image as a two dimensional array of bytes you can resize easily enough.
The power of ImageMagick is when you need to support multiple formats. Resizing BMP is easy, the hard part is supporting the various ways that data is encoded.
