Figure 4.

Examples of volume rendering based on the true colors of the histological stain. (a) Amira volume rendering of a RGBA stack based on 55 inverted section images taken from toluidine blue-stained resin sections of an early Cristatella mucedo bud. Because of color-inversion the background is black, and by using the inverted grayscale channel as alpha channel we achieved total transparency in these background voxels. (b) The re-inverted snapshot of the same volume. Through re-inversion the volume can be visualized using the original colors of the toluidine blue stain. (c) Amira volume rendering of a RGBA stack based on 115 inverted section images taken from Azan-stained paraffin wax sections of Phoronis australis. (d) The re-inverted snapshot of the same volume visualized using the original colors of Heidenhain's Azan trichrome stain. Scale bar for a and b = 50 μm. Scale bar for c and d = 500 μm.