Author Topic: "in-render" chromatic aberration and other photography experiments!  (Read 2120 times)

2017-03-03, 01:17:12

mferster

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Hey all,

I've been thinking a lot about photography and lenses lately, and thought I would post some experiments I have done regarding recreating such effects in corona.

First up is a chromatic aberration test.

Chromatic aberration occurs when you have a lens that is unable to converge all the color wave lengths on the same point. Going off this knowledge I proceeded to model a lens, placed it in-front of the camera and rendered out the different color channels (R,G,B) using the tint controls in the frame buffer.  With each RGB render I changed the IOR of the lens R(1.42) G(1.45) B(1.47)[For accuracy green is always the middle IOR value due to it's place on the color spectrum]. I then took each rendered color channel and the combined them in photoshop with additive blending. Here is the result.

As you can see, like in a real camera the aberration becomes more pronounced the further away from the center. pretty neat

2017-03-03, 03:24:19
Reply #1

vicmds

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Wow, that's actually pretty interesting! I shouldn't be surprised it works as you'd expect

2017-03-03, 10:52:12
Reply #2

romullus

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Quite interesting. Could you compare it with traditional method of adding CA in post? Necessity to render everything through refractive lens and to do it three times for each view, seems for me huge overkill. Did you tried to simulate CA with custom bokeh mask? You can get interesting results that way too.
I'm not Corona Team member. Everything i say, is my personal opinion only.

2017-03-03, 17:34:36
Reply #3

mferster

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Oh it for sure isn't feasible for a standard workflow, way too cumbersome.

Here is a follow up, for some of the other options.

The first one is with the custom a custom bokeh mask, as suggested by Romullus. Unfortunately, it isn't all that accurate it only works on things that are out of focus rather than things that are closer to the edge of the frame. Also the colors don't swap  positions when they cross the center of the frame as they do with a camera. It also gives a tinged hue to the whole image.

The second is with a post process with Arion Fx for photoshop. The simulated chromatic aberration color isn't actually correct, the color shift should be reversed for it to be accurate. Unfortunately for it to work it has to blanket blur the image to get the effect.
« Last Edit: 2017-03-03, 17:43:27 by mferster »

2017-03-13, 05:12:04
Reply #4

Christa Noel

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thanx mferster! I never knew that the CA I used in post-pro is incorrect.
I think coronaTeam have to take a look at this. eventhough CA isn't commonly used in photography but in some case the color produced is beautiful.