Application of optimal image processing. The optimized image processing protocol as described in Figure 6, was applied to the four most promising papers identified based on spectral imaging (Figure 3). A: Images of roots grown on Anchor, Whatman blue and white or Sebio paper. Two images were taken with flash light from the right/left side and combined to one image. B: Conversion into greyscale using the red channel for conversion. C: Segmentation of the root system using the adaptive threshold of GiARoots.