digitize a heatmap you found on the internet
preliminary steps:
- (1) count the number of bins in each dimension
(nx, ny) - (2) estimate the number of pixels per bin, and multiply to get the total number of pixels along each axis. crop the image exactly
- (3) record the extrema of the colorbar values
(vmin, vmax) - (4) crop the heatmap to remove the black boundary
then call M = digitize_map( cropped_image_path, cropped_cbar_path, (nx, ny), (vmin, vmax) )