Vision-impaired students have several issues accessing mathematical documents, which are associated with the representation of mathematical expressions and graphs of mathematical functions. Graphs of mathematical functions are visual presentations of mathematical information and useful to illustrate numerical or qualitative information, which are sometimes difficult or even impossible to describe. A graph is a picture that shows how sets of data are related to each other. Graphs of mathematical functions generally convey the intended message of a mathematical document. Therefore, access to graphs is essential in learning mathematics. Finding a solution to represent graphs of mathematical functions in an accessible format is necessary for the vision-impaired. This paper describes an approach to develop an application to address this issue by detecting, extracting and categorising important information from graphs of mathematical functions using three open source packages, namely, ImageMagick, GNUPLOT and Octave.