  There are many resources useful for processing images, most of them freely
available and quite friendly to use. In spite of this abundance of tools, a
study of the processing methods is still worthy of efforts. Here, we want to
discuss the possibilities arising from the use of fractional differential
calculus. This calculus evolved in the research field of pure mathematics until
1920, when applied science started to use it. Only recently, fractional
calculus was involved in image processing methods. As we shall see, the
fractional calculation is able to enhance the quality of images, with
interesting possibilities in edge detection and image restoration. We suggest
also the fractional differentiation as a tool to reveal faint objects in
astronomical images.
