ImageMagick is a program capable of reading, converting and representing images in a large number of formats thanks to the large number of libraries it includes.
With ImageMagick you can crop your images, add some effects, combine text and polygons, add rotations, etc. The program supports almost 100 different image formats, from the most popular like TIFF, JPG, PNG, GIF, BMP or PDF to more specific ones.
ImageMagick also works as an image converter. In addition, the application is completely free and is distributed with its source code in case you want to alter and improve its operation.