Or, you could blur the image a little, then use the Level curves to make the data a thin black line by squeezing the fully-black and fully-white arrow tags close together. Make the image indexed with one color. Finally, save the image as a .pgm or .xpm file. (.pbm is probably ideal but it seems like GIMP can't save in that format. Perhaps use ImageMagik's convert to go from pgm to pbm?) The data format for such files is very simple and with a quick read of the relevant man page, you will be all set to read the file, dump the data into an array and then off you go. If you have lots of pictures and would like to automate the process, you could even write a script to handle the GIMP part non-interactively. This has the advantage of probably being more accurate than using the mouse for coordinates, but perhaps this is not what you wanted. If that's the case, sorry... Alan
