[APh] How do I add chromatic aberrations?

[Alex_M]

In Photoshop there's a Lens Correction filter which allows you to add chromatic aberrations to the image. How do I add chromatic aberrations in Affinity Photo? I sometimes add this effect to 3D rendered images to make them look a bit more realistic.

 

Thanks

[verysame]

You can use the Channel Mixer.

Here are the steps:

 

• Duplicate your base layer three times
• Add a Channel Mixer adjustment to each layer and nest the adjustments respectively
• Now you need to split the channels so in order to extract the red channel you pick the Green from the Output Channel in the Channel Mixer and move the red to -200 and the blue to -200, same goes for the Blue Channel, you move the red to -200 and the blue to -200. At the end of the operation, you're left with the red channel only
• Repeat the process above for the remaining two channels: so, for the green just use the Red and Blue channels and move to -200 respectively the red and blue
• Once you've done, change the blend mode of the two top layers to ADD and now you get the default beauty pass with no chromatic aberration yet
• Start shifting the two top layers in the direction that pleases the look you are looking for, you'll see the Chromatic Aberration showing up as you move the layers.

Here's an example:

 

Regular beauty pass

 

With Chromatic Aberration

 

You could even add some lens distortion, either to the individual layers or to the top of the stack, it's up to you.

 

 

This is the layer setup:

[Anna Susanna]

I was wondering about this lol,I watched how you could "get rid" of it,but not add it (yet). I also have a plug-in for GIMP,that can create this too,and was going to use that,if there wasn't a way (yet) in Affinity Photo. And Thanks for sharing :).

[Alex_M]

Thanks, verysame! A bit too complicated for my liking but at least it does the trick. I was hoping for a filter of some sort like in Photoshop. Is this something that can be added in a future update?

[verysame]

NP.

 

There's always room for improvement.

A live filter would be more convenient, but the process above seems more complicated to explain than actually doing it ;)

[ronnyb]

Record a Macro and share it on the forum ;)

[Alex_M]

I got it working with verysame's method. Now I need to know how to make the aberrations have effect only towards the edges of the image because offsetting the color channels is not exactly how aberrations work in the real world. Cameras show aberrations only towards the edges of the frame. I tried adding Lens Distortion filter in one of the extracted RGB channels but I can't seem to make aberrations appear only in the edges with it. To the contrary - it made my aberrations stronger in the center which is wrong.

 

I know I can apply a mask and mask the aberrations effect in the central part of the image but it's still not correct this way because aberrations in the real world are offset with a larger distance at the edges and less distance in the center rather than being equally offset and being less opque in the center and fully opaque at the edges. So a simple offset of the extracted RGB channels and applying a mask is not the correct way to do it. Maybe there's a filter that that I can apply to the channels that stretches the channel outwards while keeping the central part more stationary?

[verysame]

Spot on, Alex_M,

 

 

That's exactly where I stopped. Also, to finesse the effect even further, I was thinking to find a way to have a smoother transition between the separations.

A lens chromatic aberration is not that perfect. With the method posted above, by nit-picking the image one is able to tell where the shift happens.

In other words, it needs to be more organic and less digital.

Just too little time... :(

 

Anyway, for the distortion only along the edges, I was thinking to investigate some displacement technique which, theoretically, should be a good candidate as with the proper displacement map it should be possible to preserve the center and affect the edges in a smooth, balanced way.

 

Hope to find some time this weekend to play more with it.

[Alex_M]

Indeed. Do let us know here if you find an elegant solution to this. I'll do so too if I find one myself.

[anon1]

Spot on, Alex_M,

 

 

That's exactly where I stopped. Also, to finesse the effect even further, I was thinking to find a way to have a smoother transition between the separations.

A lens chromatic aberration is not that perfect. With the method posted above, by nit-picking the image one is able to tell where the shift happens.

In other words, it needs to be more organic and less digital.

Just too little time... :(

 

Anyway, for the distortion only along the edges, I was thinking to investigate some displacement technique which, theoretically, should be a good candidate as with the proper displacement map it should be possible to preserve the center and affect the edges in a smooth, balanced way.

 

Hope to find some time this weekend to play more with it.

Or maybe use the source layer

Filter > detect edges

Layer > Rasterise to mask

 

Cheers

[verysame]

Or maybe use the source layer

Filter > detect edges

Layer > Rasterise to mask

 

Cheers

 

Hm... that mask would affect the whole canvas based on the edges detected, whereas the fx should be more intense toward the edges and less in the center.

An extreme example:

[Allan Windmill]

On 2/12/2017 at 5:02 PM, verysame said:

You can use the Channel Mixer.

Here are the steps:

 

• Duplicate your base layer three times
• Add a Channel Mixer adjustment to each layer and nest the adjustments respectively
• Now you need to split the channels so in order to extract the red channel you pick the Green from the Output Channel in the Channel Mixer and move the red to -200 and the blue to -200, same goes for the Blue Channel, you move the red to -200 and the blue to -200. At the end of the operation, you're left with the red channel only
• Repeat the process above for the remaining two channels: so, for the green just use the Red and Blue channels and move to -200 respectively the red and blue
• Once you've done, change the blend mode of the two top layers to ADD and now you get the default beauty pass with no chromatic aberration yet
• Start shifting the two top layers in the direction that pleases the look you are looking for, you'll see the Chromatic Aberration showing up as you move the layers.

Here's an example:

 

Regular beauty pass

 

With Chromatic Aberration

 

You could even add some lens distortion, either to the individual layers or to the top of the stack, it's up to you.

 

 

This is the layer setup:

verysame's answer is great, but I find the set up of channel mixers can be simplified as:

- If you want just the Red channel, simply change all the rest channel's contribution to zero.

For instance, after you duplicating the original image 3 times, and rename them properly as "Original_Red", "Original_Green", "Original_Blue"; Add 3 channel mixers to each later.

Now inside the Channel Mixer for Original_Red, select green output and change its green contribution to 0, select blue output and change its blue contribution to 0.
Similarly, inside the Channel Mixer for Original_Green, select red output and change its red contribution to 0, select blue output and change its blue contribution to 0.
Finally, inside the Channel Mixer for Original_Blue, select red output and change its red contribution to 0, select green output and change its green contribution to 0.