There was a discussion about a related problem a few months back, and the general consensus was: not really possible. I have done things like this, very time consuming, limited accuracy. If you want to scan the data and use it in a document, probably OK. Attempting to retrieve data from the graph, you will loose lots of precision. I would suggest that you get data from original sources if you can. If you can't, too bad. Edward Cannon
On Mon, Feb 7, 2011 at 1:39 PM, <[email protected]> wrote: > Greetings: > > This is a question probably more related to machine vision, but I want > to digitize a lot of hand-drawn graphs that we have accumulated over > the years. I would like to scan them, have a clerical person select a > line on the graph (maybe in several spots), and get back a set of XY > coordinates of the line. (A bonus would be to select points on the > axes and enter the values to automatically do scaling.) To confound > the process, there is a grid on the image, and there are several lines > which may cross each other at various angles. > > My first thought is someone must have had this problem before and > solved it -- if so, can I adapt your solution? (There was a product > available commercially, but it didn't work worth a darn.) > > If not, can anyone suggest an approach? My first thought is to > set an image threshold to convert it to ones and zeros, then do some > kind of line-following algorithm that would take guidance from a > human being. Fortunately, the desired data form smooth curves. > It will be hard to discriminate between the line and the grid though. > > Regards, > Allen > -- > Allen Windhorn, P.E. (MN), CEng (507) 345-2782 > Kato Engineering > P.O. Box 8447, N. Mankato, MN 56002 > [email protected] > _______________________________________________ > Image-SIG maillist - [email protected] > http://mail.python.org/mailman/listinfo/image-sig > _______________________________________________ Image-SIG maillist - [email protected] http://mail.python.org/mailman/listinfo/image-sig
