Imaging systems with weathering detection pixels

An imaging device may have an array of image sensor pixels. The array of image sensor pixels may have main pixels and reference pixels that are overlapped by optical stacks. The reference pixels may be more resistant to weathering, such as solar degradation, than the main pixels. For example, optical stacks overlapping the main pixels may include antireflection coatings, while optical stacks overlapping the reference pixels may not include antireflection coatings. Alternatively or additionally, the optical stacks overlapping the main pixels may include color filter resist formed from a first pigment, and the optical stacks overlapping the reference pixels may include color filter resist formed from a second pigment that is more resistant to weathering than the first pigment. Processing circuitry may compare outputs of the main pixels and the reference pixels to determine whether pixels in the array have been damaged.