Wednesday, March 25, 2015

adobe photoshop - What is this shifted red and blue effect often seen in VR called? How can I achieve it?


I'm looking for more information regarding a specific type of visual effect that I have been trying to recreate many times in Photoshop, without any success. I would like to learn how to do this from tutorials, that is if I knew what to search for.


Below I have an image from an Oculus Rift game, and another from a movie trailer (Kung Fury). Notice how light at the edges of objects diffuses into two, sometimes three slight red green and blue colors (RGB). What is this effect called? Obviously the examples are very not alike but the result is pretty much the same thing, and I really want to learn how to accomplish this in Photoshop.



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Sorry if the question looks kinda dumb, but I knew no other place where I could ask this.



Answer



This is called chromatic aberration. Here's an example from Wikimedia:


Chromatic aberration (comparison)


The Oculus Developer Guide (PDF) provides a nice explanation:



Chromatic aberration is a visual artifact seen when viewing images through lenses. The phenomenon causes colored fringes to be visible around objects, and is increasingly more apparent as our view shifts away from the center of the lens.


Fortunately, programmable GPUs provide the means to significantly reduce the degree of visible chromatic aberration... This is done by pre-transforming the image so that after the lens causes chromatic aberration, the end result is a more normal looking image.




So the effect your seeing is added to the virtual reality games to actually reduce distortion due to chromatic aberration. I've found an interesting PDF that explains this technique: Improved Pre-Warping for Wide Angle, Head Mounted Displays


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