How i did this : keep a new layer, make a line with default gradient black and white color, go to render - differnce cloud - push control "I" which will invert the position.
Now go into the curves and enhance the white part and then cut the un wanted black area, after that you need to manage the thresh hold to make it look real, and on the back ground layer you can put filter - render - lense flare where ever require. . .
