  Images are used frequently in plant phenotyping to capture measurements. This
chapter offers a repeatable method for capturing two-dimensional measurements
of plant parts in field or laboratory settings using a variety of camera styles
(cellular phone, DSLR), with the addition of a printed calibration pattern. The
method is based on calibrating the camera using information available from the
EXIF tags from the image, as well as visual information from the pattern. Code
is provided to implement the method, as well as a dataset for testing. We
include steps to verify protocol correctness by imaging an artifact. The use of
this protocol for two-dimensional plant phenotyping will allow data capture
from different cameras and environments, with comparison on the same physical
scale. We abbreviate this method as CASS, for CAmera aS Scanner. Code and data
is available at http://doi.org/10.5281/zenodo.3677473.
