Image processing
To allow standardisation of colour measurements, a Spyder
CheckrĀ® 24 card (Datacolor, NJ, USA) was scanned in
the flatbed scanner under the same settings as the diaspores, and used
to calculate a colour conversion matrix (CCM). The CCM was then applied
to images for optimal colour reproduction
(https://github.com/rdayrell/colour_calibration). In some images,
undesired elements, such as broken seeds and particles, were removed
from image with the brush and clone stamp tools in Adobe Photoshop.
Images were saved in PNG format throughout all processing steps to avoid
compression artifacts. Processed images (Figure 5) comprise the image
dataset and were used as inputs for automated trait extraction.