Luminous Landscape Forum
Raw & Post Processing, Printing => Adobe Lightroom Q&A => Topic started by: dreed on September 30, 2011, 06:23:49 am
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Are there any plugins for Lightroom that can correct the polarisation of a blue sky for photos created with a circular-polariser?
What do I mean by correct?
Using a polarising filter can often result in part of the sky being a nice dark blue but other parts being closer to white. A plugin to correct that would look for deep/saturated colours and then spread that throughout the sky in the image.
If none are available, how hard is it to develop a LR plugin?
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Under PS, such a work might be conceivable but probably not easy (select the sky only, with a nice cutout work for the tree branches at the edge ;D, and in this selection equalize S and L -if not H- layers).
Under LR, it's much easier to shoot without polarizer, and then bring the L down and the S a tad up of the blues in the HSL panel.
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Are you using your polarizer on a wide angle lens? That's the only time I've seen the extremes in the polarization that you're describing (dark blue to near white).
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Are you using your polarizer on a wide angle lens? That's the only time I've seen the extremes in the polarization that you're describing (dark blue to near white).
+1 ... I'd say the solution is to avoid using a polarizer with wide-angle lenses pointed at the sky ...
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As others have pointed out this usually happens when you are using a lens with a long dimension angle of view greater than the equivalent of what you get with a 28mm lens on a 24x36mm format frame ( example if you are using an APS-C format camera any focal length shorter than 19mm ) or if you are using a polarizer on a shorter focal length lens but shooting panoramas. This is simply the physics of polarization at work.
If you absolutely need a polarizing filter (hey it happens) a hypothetical solution might be to shoot multiple frames of the scene with the polarizer rotated to different angle and then in Photoshop build a layered composite. Once you are satisfied with the blending job in the sky, flatten it and add it to your Lightroom catalog. I'm pretty sure this would make it very difficult for a panoramic stitching program but it seems to be worth experimenting with.
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An evenly blue sky would look as fake as hell. It would take some pretty fancy programming to make it look real.
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Depending upon where the blue part is vs the white part, and your desired results, you might be able to use the Graduated Filter to get a result you like better. Don't forget it can do a lot more than just GND, it can introduce colors and modify exposure, brightness, contrast, saturation, Clarity, Sharpness. And you can use multiple filters on top of each other. It's pretty powerful.
Good luck, Bob.