Strange colors between sprocket holes?

I used to see that effect a lot near the ends of large motion picture film rolls. As it was always near the first few wraps of waste film, I never worried about it much. I do suspect that it was near the light trap of a film magazine. If this is reloaded from a larger roll, I'd suspect something like that.

Martin

Likely it is plain exposure of at least one side of a spooled film. Not limited to the sprocket area, but on the whole width. The outer layers shading the inner layers. Only at the perforation holes, slightly overlapping, the light penetrated to deeper layers, resulting in typical back-light red-fog. The fully exposed outer layers were discarded.