Camera lens; large speck like dust; gives a slight center color cast on raw images.
(cast is hard to detect or not so obvious; noticeable in the resulting images)
Best ways in removal; so as to restore back original color?
Shoot against a black or dark background at all focal lengths to determine size and color of speck cast?
Then apply counter numerical filters or certain tools in removing the cast then somehow adjusting the area colors back to original?
Or another alternative method?