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Shaders In Games: Bloom In Post

For this week’s blog I wanted to go over something that was taught in the tutorial this week. Hopefully if I try to explain it here will help me learn how this process is done. The process I am talking about is adding Bloom in post rendering. So the process to do this can be done in four steps. Each step is done with a FBO (Frame Buffer Object) and a shader program that is applied to it. The steps are: a scene pass, a blur of the scene, then a bright pass to emphasise the bright area, then you composite the layers. It has been stated that ant effect that you can do in Photoshop can be a shader and become the end result for your game. Let’s bloom a picture in Photoshop first.

  I have taken a picture and put it into Photoshop. First we will do the scene pass and blur. For the scene pass that is an easy one it is just duplicating the layer. Then we go to Filter->blur->box blur. We are going to use a box blur because it is easy to do and we will get a good result.

  Now for the bright pass. This can be done with levels or curves take your pick. Using levels is straight forward, take the slider and crush the blacks so that you are left with just the bright area showing. Any bright areas will affected and the dark ones will not.

  And for the final step we are going to take the layer that we have been working on and blend it into the original. In Photoshop we can do this with layer blending. We are going to use the blending mode screen. This will add all of the bright area and forget the dark ones making the bright brighter.

  Once you have done all the steps above you can see the final product. The first picture is the original and the second one is the bloomed one.