CVL is a library for image and data processing using graphics processing units (GPUs). It is suitable as a base for GPGPU applications. Cvtool is a general-purpose computer vision tool that is based on the CVL library. It works as a filter by reading streams of data from standard input and writing manipulated data and/or analysis results to standard output. Complex analysis tasks can easily be realized in scripts. Many image and video manipulation and analysis functions are included, as well as some advanced computer vision techniques.