how to extract data from an image graph

I'm looking to get that from a graph. but problem is that graph is in image form. Now I want to extract data in excel from that graph. how can i do it? I'm using office 2003.

Use Graph Extract Program. It is a free Windows based program to extract data from any graph image. You can load the graph as an image in the program and extract data in tabulated format. The program will accommodate linear, log-linear and log-log plots, and will work with scatter plots, line plots or bar charts. Extracted data can be viewed in CSV viewer or Excel program.

Good Luck!

I think that what you're looking for is a digitizing software. Have a look at im2graph.

Here's an overview from the website:

im2graph is a free digitizing software that converts graphs and plots to data, that is, to numbers. With behind the scenes fast and efficient image processing algorithms, im2graph effortlessly converts images to graphs with a click of a button. For more complex use cases,a highly tuned user-assisted GUI is available, enabling fast and effortless conversions from graph images to values. Using im2graph is intuitive, addictive and fun and requires very little knowledge or effort on your part. im2graph is the OCR equivalent of graphs– instead of converting scanned images to text, im2graph converts scanned graphs to data.

You can download it directly from the website. There's a user's manual that comes with the software but you can also read it online.