Bloom is used to reproduce the effects that occur in real cameras when taking pictures in a bright environment. The bloom effect simulates fringes of light extending from the borders of bright areas, creating the illusion of a bright light overwhelming the camera.
The following figure shows bloom at the entrance of the cave in the Ice Cave demo:
Figure 5-62 Bloom at the entrance of the cave as implemented in the Ice Cave demo
The bloom effect occurs on real lenses because they cannot focus perfectly. When the light passes through the circular aperture of the camera, some light is diffracted creating a bright disk around the image. This effect is not typically noticeable under most conditions, but it is visible under intense lighting.
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