Reference for the math behind transform.get_matrix_m

[cgpadwick]

I was wondering if there was a link describing the math behind the function get_matrix_m in color_correction.py (https://github.com/danforthcenter/plantcv/blob/main/plantcv/plantcv/transform/color_correction.py#L215) that someone could point me to. The standard approach would tend to match that in affine_color_correction. The approach in get_matrix_m looks interesting and wondered if there was a reference anywhere that I could review. Thanks!