Step 1: Select control points

For example, here is a orthogonal coordinate images as 'gird.bmp' and taken calibration images 'calibration.bmp'. Using cpselect, we can relationship between control points of pair images.

cpselect('grid.bmp','calibration.bmp')

The control points are landmarks that you can find in both images.

The number of control points depends on which transformation will you used. The `projective' transformation requires 4 pairs, the linear, second and third order polynomial transformations require 2, 6, 10 pairs. After selection of pairs, please save the data.

Save control points by choosing the `File menu', then the `Save Points' to Workspace option. Save the points, overwriting variables input_points and base_points.