Where o is the point-wise multiplic

Where o is the point-wise multiplication trying to express the interaction effects of background layer and rain layers saying internal refraction and reflection. Comparing to linear composite model, blend model assumes that the background and rain layers have impacts on the performance of each other, the internal display of image can be determined according to the exposure radiance, which means that when the light is sufficient, the background layer in the image will show vividly, and the interference of the rain layer will not have much impact. On the contrary, if the light is in poor condition, the contrast between background layer and rain layers is not obvious enough which means the rain layer show great interference.