In the middle corona, medium frequencies were boosted in the azimuthal direction but very high frequencies were suppressed for all orientations. Finally, in the outer corona, middle and high frequencies were suppressed, but much more strongly in the radial direction than in the azimuthal direction. This had the neat effect of letting what would otherwise look like a set of disorganized slightly brighter film grains lying along a radial line from the sun snap into a faint coronal streamer when the filter was turned on. A special localized high pass boost filter was applied to bring out a magnetic loop near the sun's southwest limb. The input photographs, other photographs and photographic mosaics, and my memory of the eclipse all served as guides to check on particular coronal details and other aspects of the mosaic.
Color rendition is one of the more artistic aspects of the mosaic.
The trick is to preserve the color balance of the image in the face of locally varying and enhanced image intensities. This produces unrealistic results. The upshot is that darker inner corona areas should take on a more truly yellowish gray appearance rather than the blue sky color that is only appropriate in the outer corona. The inner corona was portrayed as mostly white with a slight hint of yellow, I took the color of the sun itself as a guide. A starting point in producing these color relationships were some color scans of photographs made for an earlier version of the mosaic.