FIGURE 12. Two
specimens of Chancelloria and one of the sponge Vauxia from the
Burgess Shale, British Columbia (ROM 49605). Immersed in water. A.
Without crossed nicols; green channel. B. With crossed nicols; green
channel. C. Image obtained by subtracting the pixel values of B
from those of A, using the Adobe Photoshop “Subtract” blending mode
(settings: Opacity = 100, Offset = 100, Scale = 1) and subsequently adjusting
the levels in the combined channel. D. Image
obtained as in C, except that values of A are subtracted from those of B (this
has the same effect as inverting the values of C). (Click on the picture
to toggle between different views, or select one of the following links: A,
B, C, D.)