Engauge digitizing software converts an image file showing a graph or map, 
into numbers. The image file can come from a scanner, digital camera or 
screenshot. The numbers can be read on the screen, and written or copied 
to a spreadsheet. Engauge Digitizer compensates for rotation, scaling 
and skew (also known as shearing) in graphs. Engauge recognizes BMP, GIF,
JPG, PNG, PNM, and XPM bitmaps.

This requires fftw (and qt3 from the /extra/kde3-compat/ packages).