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.