Having gone through quite a few libraries, the ones that intrigued me the most are Boost.Algorithms and Boost.GIL. I had an idea for Boost.GIl in fact. Basically what I wish to propose(please do correct me if it already exist) is a library that will have the functionality to convert a image to a negative one (I found the conversion of colour image to black and white functionality, but not this). Also, the process can be massively sped up by the incorporation of parallel programming paradigms like OpenMP. Do let me know what you guys think about this.