After image is the term used for the image that persists in the eye even after the original image that the eye was being exposed to is removed.
After image is a type of an optical illusion and can either be a positive or a negative after image.
If the colors of the original image is retained in the after image then this is termed as positive after image.
If the colors of the original image are reversed in the after image then this is termed as negative after image.
After image can occur either due to a prolonged exposure to a very bright light against a dark background such as headlights or after a prolonged exposure to a colored image.
NPP can be directly assessed by measuring plant traits or harvesting plant material on the ground, but across large areas remotely sensed images can be used to estimate NPP.. im trying to help
