GRABIT - POLYFIT

Grab data off an image with the ability to fit a polynomial over the selected data points.

Modified version of GRABIT by Jiro Doke, see this function for the full original description. Jiro Doke deserves all the credit, I just found this modification useful and would like to share it to those who can also use it.
Functions the same was as GRABIT, but a feature is added to plot a polyfit over the image and data points. This is useful if the order of the fit is not known, and you would like to see the fit over the original image. Original GRABIT directions below:
Following steps should be taken:

1. Load the image file.
2. Calibrate axes dimensions. You will be prompted to select 4 points on the image.
3. Grab points by clicking on points. Right-click to delete a point. Image can be zoomed during this stage.
4. Multiple data sets will remain in memory so long as the GUI is open. Variables can be renamed, saved to file, or edited in Array Editor.

Panning is achieved by clicking and dragging on the image. In addition to using the zoom button, there are keyboard shortcuts for zooming:

<shift> - center view
<a> - zoom in
<b> - zoom out
<space> - reset view

Again, a big thanks to Jiro Doke for the original code, it is a very useful tool.