Correcting lens distortion – what's your method?


(BenjaminJohnson) #1

Hi,

I’ve been sort of obsessing about this for a little while now – I’m trying to determine the best course of action when it comes to dealing with lens distortion.I started out using Photoshop’s Lens Correction filter which works ok in a generic kind of way, then I gave DxO a shot which works extremely well for distortion correction (more on that in a minute), and recently tried Capture NX 2 as I noticed it has lens correction as well. This got me pretty excited at first as I thought Nikon must know their lens characteristics even better than DxO does, but it seems their correction method is more along the generic lines of what Photoshop does rather than truly customized to a particular lens and when comparing it to DxO results, they don’t look quite as good. I’ll give Nikon credit for at least making it “automatic” and possible on NEFs.Back to DxO – The main issue is distortion correction is really all I want to use it for and I’m a little frustrated by how it integrates with Lightroom – I can’t (or shouldn’t, according to DxO) make any adjustments to my file in Lightroom prior to correcting distortion which seems totally ass-backwards to me. IMO, distortion correction should be the last or next to last step if you’re output sharpening. I want to be able to make all my image edit to the RAW data and then I’m happy to duplicate the files that require lens correction (obviously correcting distortion right in the RAW file would be ideal – ahem, Adobe?).

Please help.

I didn’t find the right solution from the Internet.

References:-
https://arstechnica.com/civis/viewtopic.php?t=45031
Motion graphics agency

Thanks!


(Marie-Catherine) #2

Hello @BenjaminJohnson,

Our modules to correct optical defects, including distortion, are made with measurements done on specific targets. For distortion we look at variation of defect on focal length and focusing distance. So our modules are pretty accurate to the lens profile.

If you want to use distorsion correction but apply it on RAW I can suggest to go first in PhotoLab and save your images in dng. Apply only distortion correction and maybe denoising which is really good in PhotoLab :slight_smile: Then all color management, exposure, etc. will be handled by Lightroom.
We have a plug-in for LR that allows automatic export and import from one soft to the other.

regards,


(Rick - Bay Area) #3

DxO Lens Correction Modules coupled with ViewPoint… What can be better than that?

I’d rather sharpen a corrected or distortion free image before final sharpening and output.

Maybe I don’t understand?


(Platypus) #4

What is distortion correction? It changes the location of your image’s pixels in a way to make crooked lines straight. But the source pixels are in a well defined position and if you move the pixels, they will miss their target location more or less because target positions also exist in predefined positions only. Correcting geometric properties of a lens will therefore introduce some (geometric) noise in your images. Geometric noise means that lines/edges will be less sharp than they were before correction.Whether you’ll see this or not is another discussion though…

My methods sticking to raw:

  1. As Marie-Catherine proposes (general, mixed/nature shoots)
  2. Open original folder with DPL, correct images where necessary, save to Lr (architectural shoots) Note: Just lens distortion, leave keystoning etc. alone, Lr handles this easily and I prefer Lr’s crop functionality.

Caveat: DPL can cause colors to change in a way that makes them hard to correct in Lr. See here for details: https://feedback.dxo.com/t/export-to-lightroom-kills-reds/1455


(Rick - Bay Area) #5

I see what you are saying. You want to maintain as much non-manipulated integrity as possible prior to output. Thanks for explaining.


(Peter) #6

probably not really your question answering but reading your quest started me to think about what is optical and what is perspective, non lens error , but point of view?
And this artical is rather clearing that up.
and spherical aberration
and chromatic aberration

So the optical module on dxo does three things in one automatic go,
pincushion/barrel things, aberration and vignetting.
and some things like lens corner light losses. Shading which is the mild form of vignetting.
comparing to my other program vignetting can be done better at first glans but i find out that dxo has a wider image angle, uses less crop or uses more of the sensor?, to cut out vignetting. cropping to the same angle is the same.

same as chromatic ab. at first it looked less good to fine tune but because of the non realtime viewing of the corrected image the ab correction kicks in when zoomed in.
there lens sharpening optic module does give a instant kick in the right direction.

So as far as optical correction without any manual help it is doing a fine job i think.

as far as viewpoint correction the auto mode does surprise me that it over shoots on occation at 100% and gets unnatural. but tuning down to 75% does help.
That artical does showed me why, The brain corrects by sampling wile looking up, focussing at smal points and rebuilding that to straight lines in your brain like to look at it at a more distance,
If you over correct the image by straighten al lines, your place of eye hight is lifting to a point that you standing at 4m high. in stead of on the ground. and thus looking unnatural. the same theory goes for horizontal lines so some / and ( •> in horizontal lining is needed.

Al this has nothing to do with your question but more understanding what your doing wile correcting and that is also the case in applications. Atleast in my case, i learn every time how less i know of theoretical details as a non trained photographer. who just enjoys taking pictures and enhance them in post.(read correct my flaws😋)
As platypus explained correction is changing location of pixels and i believe its best to do that with the highest resolution, most pixels, and in one application from raw.
and if one app does things better then others most is due knowledge of handling the tools or there automated algorithm does help you more.
So i think its best to do all corrections geometric/viewpoint and optical distortions, like barrel things and flaring and aberrations in one raw developer. to get less artifacts and mismatches by faulty placed pixels.
And if a other app does something better and if i used that application longer its more likely my lack of craft. (That all said i heard LR is rather good in autocorrecting, :blush:)

so in sort (ish): i practice and learning as much as i can of one application and try not to export to much in threetrap stages, . i did it before between two rawdevelopers and it started to frustrated me that there wasn’t a perfect transition point for general alkinds of images. color errors. you can do double correction in dng of wb , color and exposure and contrast and such , dng is linear raw so not real raw. So colors didn’t looked the same after transition but also not nontouched, double work in color taste and WB,

So it is the dxo labguys job to close the gabs and holes in Pl suite. so we don’t need LR or Capture one or Silkypix or … :blush: