Leptonica is open source software that is broadly useful for image processing
and image analysis applications.
Featured operations are:
Rasterop (a.k.a. bitblt)
Affine transformations (scaling, translation, rotation, shear) on images
of arbitrary pixel depth
Binary and gray-scale morphology, rank order, and convolution
Seedfill and connected components
Image transformations combining changes in scale and pixel depth
Pixelwise masking, blending, enhancement, arithmetic ops, etc.