Hey,
You can get the plot information by interpolating the data. For 1-D data interpolation you can refer interp1 function of MATLAB and for 2-D data you can refer interp2 function of MATLAB. Both functions can be accessed from the below links.
This can also be tried to be solved by finding the plot equations and getting the value of unknown variable by putting the known variable. If the graph looks linear in a region, it can be approximated to get approximate values as well.
To do so, you can try curve fitting to the available data. You can refer this link for more information regarding the same.
