I used to digitize experimental curve with engauge. However, I don't know how to digitize a curve evenly using it? Could anyone has such kind of experience or using other software? Thanks advance.

What do you mean by "evenly"? Smoothly? Using engauge you have full control over the sampling locations. Choose them by hand instead of trying to digitize the curve automatically. Spending this effort will usually give much better results.

Try Plot Digitizer, its free!

http://plotdigitizer.sourceforge.net/

The 'evenly', I mean the independent variable is evenly. Like function F(x,y), the value of x is evenly, say 10, 20, 30...., then get the value of y from the curve.Can engauge do that. You know by hand you can't locate evenly the value of x.

No, I don't think engauge can do that. I also used Plot Digitizer (suggested by agg), but don't remember such option.

Well, what you can do is digitize the curve by choosing points by hand (this way getting a smooth result), and output the data points to a file. Then you use a second software (try xmgrace, which is a superb data plotting and analysis tool), to interpolate your curve on a specified abscissa (e.g. uniformly). If you don't have xmgrace, or any equivalent tool, you could also write your own little program to read the sampled data and interpolate it. That wouldn't be difficult to do.

I see, Thanks a lot!