I have a series of clips taken on an overcast morning in natural light. As time progressed, the overcast thinned and some of the clips are noticeably brighter than others. In order to adjust the luminance of the brighter clips to match the luminance of those taken earlier in the morning, I used the curves tool to "compress" the higher luminance values in the brighter clips and it worked just as expected.

However, the curves tool also introduced some interesting (unwanted) artifacts. There is a power pole in the far background that, for lack of a better technical term, "sparkles". The pixels around the outline of the pole appear to turn on and off in a random manner.

I can fix this easily enough but I'm curious about the cause of this odd effect. Does anyone know?

JackHughs