From Nickolay Rodionov:
Graph Digitizer is used for digitization of orthogonal graphs (scanned from books, papers). The input graph image file should be in BMP, JPEG, TIFF, or GIF format. Image of the graph can be scanned or pasted from clipboard. A bad image map can be edited and rotated. A tie to real coordinates of chart implements by allocation of rectangular area and coordinates setting of two points. There are three modes of digitization: Automatic digitization - you define curve color and area of search, Semi-automatic digitization - when you move cursor on (along) a curve, and Manual digitization - you click in a point, the value is recorded in the table. Tabled data Y(X) may be edited and saved in data-file format, or pasted into clipboard or MS Excel.