This could be usefull, but wouldn't this result in a regular blur in images with more details/transitions? You might also want to tap diagonally, because the colored dots in your image are stretched in horizontal and vertical direction.

If you want to do a real bloom, you should first do a bright pass where you filter out the dark parts, then blur that and then mix it with the original image. If you are interested I could send you a non-working example project. The shaders are written and they all work seperately, but I couldn't find a way to properly use the result of the first shader in the next because if the view-entity isn't perfectly alligned to the screen the image will be offset..