How to analyze the data from a graph saved as a .png image?

Hey!

I have this .png image of some graphs and I want to store the data of all the info found in this type of graph (turbine graphs), in different vectors. Can anyone help?

[Miguel Capelo]

For instante, in this case identify the best efficiency point and its efficiency (94.12), and the Q, H and Power for that point (6.45 m3/s, 24.05m and aprox. 1.4MW)

Answer 1

[KSSV]

Try this file form file exchange: https://www.mathworks.com/matlabcentral/fileexchange/7173-grabit

Note that it is a tedious job and it is on our patience.

[Miguel Capelo]

I've already seen that, but with Grabit you have to do it yourself for every image (calibrate the axes, etc). Isn't there any code to do that automatically?