GSA Image Analyser is a program for the scientific evaluation of 2D images (image analysis). The possibilities of the program are varied and can be divided in three main groups object surface calculation, object length calculation and object counting. The surfaces of all recognized objects are automatically calculated. In addition the surface calculation of single objects is possible. The program offers the possibility to calculate the relations of the ascertained surfaces to each other and to the whole image or background. The GSA Image Analyser has a set of functions which have been developed especially for the direct length calculation of very complex and much ramified objects. In addition to the direct length calculation, an indirect calculation with a grid intersection (developed by Tennant) is possible. For this function, the grid size can be freely defined. The automatic count function determines the number of all recognized objects and, offers the possibility to count overlapping objects apart. This separation can make over the object form, the object surface and over the object intensity.The grid intersection count function serves for the indirect object number regulation. Beside the automatic count functions, the program has two manual count procedures included. One method marks the objects inside of the image and the other cuts the image into several smaller parts to make it easier for human eyes to follow many small objects. The GSA Image Analyser can read known picture formats (JPEG, GIF, TIFF, BMP, and PNG). The program provides interfaces to scanners, microscopes, and digital cameras (TWAIN) as well as to video cameras (Video grabber, TV cams).