Edge color cast of SLR photos

What is the concept of edge color cast? Is the color of the corner and middle part of the whole photo different, or is the edge of the object in the photo colored?

If the corner color is different, it should be because your lens has dark corners and the coating is not good. Dark corners themselves darken the color. If the lens color correction is not good, the darkened color may be biased towards other tones.

If the edge of an object has obvious colored edges, the term is called dispersion. Generally, it is mainly blue or purple. Usually, film heads are used in digital machines. Because the optical path has not been corrected, it produces a prism-like color separation effect at the edge of Gao Fancha, resulting in a colored edge, which is usually more obvious at the corner of the photo.

Basically, it's the lens ... if it's a dark corner, you can add a bright and dark corner with ps or lightroom, and then adjust the tone to eliminate it. Dispersion can be corrected by lens correction tool.