How do you deal with chromatic aberrations?

[sgofferj]

Hi,

one of the reasons why I don't use MLV that often yet is that with my 24-105 f/4 L IS I have really lots of chromatic aberrations. The worst is water and sunlight but also many other scenes in the nature are prone to it. When shooting h.264 with my 6D, the camera seems to process the aberrations out but in MLV they are really massively visible and ugly. How do you deal with those? Do you just ignore them or do you have a workflow to remove them in post? Maybe some Resolve plugin?

-Stefan

[Danne]

Tried acr?

[sgofferj]

ACR?

[ansius]

Adobe Camera RAW

[sgofferj]

No, never heard of it... For photos I use Darktable but AFAIK that can't be scripted, so applying the chromatic aberration filter to all DNGs of a sequence would be fairly tedious...

[ansius]

you can also look at RawTherapee, quite powerful tool, not the fastest tough, and can be unstable on windows (at least mine is)

[Levas]

Are you sure its chromatic abberation( colored borders in high contrast scene, bleu, red or purple)?
Or are you talking about moire( colored particles(not borders) in parts of the frame with lots of detail)?
Is it worse on wide angle, 24 mm then on 105mm, then its probably color moire.

I see lots of moire on my 6d mlv files, and fix it in post(raw therapee).
But for color moire most video editors can be used, seperate luma and chroma channel and apply a blur on the chroma

If it truly is chromatic abberiation, you can try raw therapee and use the 'defringe' tool( normally works for purple fringing), but you can adjust the colors it should look for, so also works for blue and red.

[Danne]

Put up an examle dng. I think ACR does a decent job and it,s fairly fast to apply.

[sgofferj]

@Levas: probably both but in this instance I'm talking more about aberrations, I think. Imagine pointing your camera to water on a sunny day. The sparkle of the sun is full of purple spots... I do a lot of nature photography and I love high contrast scenes and that's where I usually see purple dots or fringes.

[sgofferj]

Sample DNG: http://home.gofferje.net/ML/M16-1151_000085.dng

[ansius]

in that DNG I see moire color artifacts, not aberrations.
please read this: https://en.wikipedia.org/wiki/Chromatic_aberration

and with moire it is easier to deal while shooting.

[Danne]

http://www.mosaicengineering.com/products/vaf/6d.html

Havn, t checked the file yet but if it, s moire maybe above could help.

[Levas]

I would call that color moire too.
It's due to the combination of high detail/contrast and the line skipping video in the 6d (in video mode, it only reads ever third line of sensor).

I've uploaded some processed examples of your file:
http://drive.google.com/folderview?id=0B1BxGc3dfMDaWWJ0V3haR3lzN1U&usp=sharing

The jpg's are done with RawTherapee (free/open source raw editor).
The beauty of RawTherapee is that it offers different debayering options.
Most raw editors use some form of EAHD debayering, which gives bad results with line skipping Canon raw video.
LMMSE debayering works much better, the jpg also includes defringing(the purple stuff), also available in raw therapee.

Another option to get rid of it is in a video editor and somehow separating your color channels to luma and chroma (so RGB->LAB or YUV)
After separating, apply a blur to the chroma channels in LAB that means, blurring the A and B channel and in YUV that means blurring the U and V channels.
This was done in the Davinci resolve tiff file, which I had also scaled to 1920 wide resolution.

There's also another tiff file, it's the rawtherapee LMMSE file upscaled in Davinci Resolve.
Which is the workflow that I think that gives me best result.

Quickest option is loading the dng's in Davinci Resolve(or another video editor), set the clip to LAB color space, deactivate the L channel and apply a blur.

[DeafEyeJedi]

Excellent work @Levas!

[sgofferj]

@Levas:
Wow, thanks for te effort! I'll definitely try those out!

[sgofferj]

So, I have been tinkering this weekend but I couldn't figure out how to change the color space in Resolve 12. Any hints on that?

[Levas]

You can change color space when you are in the 'color' tab/window.
Here you can do a right mouse click on a node( the miniature clip in the upper right window.
If you do the right click on the node you can see colorspace and ser RGB is selected by default, choose YUV or LAB.
Under the colorspace menu you see also the three channels, which are enabled by default.
Declick the first channel, now you can apply a blur, most of the times, a radius of .75 is enough.

[sgofferj]

On a node... ah, thanks!

[JeDaiL]

Levas,

This helped a lot to deal with those ugly artifacts in Resolve.

Would you have an alternative in premiere to do so?

Does the 5Dmkiii suffer with those?


cheers

J

[Levas]

I have the 6d, so I don't know how good the 5dIII is, but it probably does a far better job, because it doesn't use lineskipping for video recording.
I don't have any experience with Premiere, but most video editors are able to separate a video in a luma and chroma part or change the colorspace to YUV.
Once you are able to only applie a blur to the color channels (the UV channels in YUV space) this should work.

[andy kh]

Great job levas

[JeDaiL]

Thanks alot for your contribution Levas!