The right image was inverted, reduced to a 50% transparency and overlaid on top of the left image.  Differences between these images are the regions that are not uniformly gray.  The apparent relief to this image tells us what is in front of what.  It also indicates color/contrasts.

L from R subtraction

This is a gray anaglyph version of a region of interest enlarged 2X.  If one uses SPM to zoom inot an image they can crop, save as a cropped version, and zoom agiain.  This reduces the image to a managable size as in the version below.
cropped closup gray anaglyph

Do the clouds look further away than they should?

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