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Author Topic: Correcting out of gamma problems  (Read 654 times)

vanderloo

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Correcting out of gamma problems
« on: April 19, 2017, 05:50:08 PM »

I hope I chose the correct forum. Otherwise please advise.
Wondering what the best method is for correcting out of gamma colors in lightroom cc.
I'm using ProPhotoRGB color space. I have several sunset shots from Costa Rica that all have the same issue.
Thank You

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Mark D Segal

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Re: Correcting out of gamma problems
« Reply #1 on: April 19, 2017, 06:16:40 PM »

If there are recoverable highlights you can reduce Highlights until they come into gamut, add masks and reduce highlights again. But if there is complete burnout, you cannot recover real information and will need to "heal" or "clone" with a good deal of feathering either in LR or PS.
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Mark D Segal (formerly MarkDS)
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Jim Kasson

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Re: Correcting out of gamma problems
« Reply #2 on: April 19, 2017, 06:28:57 PM »

I hope I chose the correct forum. Otherwise please advise.
Wondering what the best method is for correcting out of gamma colors in lightroom cc.
I'm using ProPhotoRGB color space. I have several sunset shots from Costa Rica that all have the same issue.
Thank You

First off, I think you mean "gamut" not "gamma". If you're shhowing us a soft proof screen, these are colors in your edited image that your printer can't print.

Make a small test print. You may like the way the color management software on your computer maps the colors that are OOG to what the printer can print. Tyr both Relative colorimetric and Perceptual rendering intests.

If you don't like what you see, you'll have to take matters into your own hands and edit the colors. Try local desaturation first.

Jim

BobShaw

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Re: Correcting out of gamma problems
« Reply #3 on: April 19, 2017, 07:53:37 PM »

I think even more "first off" is that this is not a sunset shot. Sunset and sunrise are defined as when the top of the sun crosses the horizon.
There is little you can do to fix it other than what others have said.
Do you have and shots taken later? Work on those.
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bjanes

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Re: Correcting out of gamma problems
« Reply #4 on: April 20, 2017, 10:01:36 AM »


First off, I think you mean "gamut" not "gamma". If you're shhowing us a soft proof screen, these are colors in your edited image that your printer can't print.

Make a small test print. You may like the way the color management software on your computer maps the colors that are OOG to what the printer can print. Try both Relative colorimetric and Perceptual rendering intents
If you don't like what you see, you'll have to take matters into your own hands and edit the colors. Try local desaturation first.

Jim

I suspect that the out of gamut situation has more to do with luminance than chroma (saturation). For example, we can compare the gamuts of the Epson 3880 using Epson Premium Luster paper using the slicer function in Colorthink. At L* = 90, the gamut is very small and it is considerably greater at L* = 50. I suspect that the out of gamut areas are blown out and you can try recovery as Mr Segal suggests and also play with saturation.

Bill
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Mark D Segal

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Re: Correcting out of gamma problems
« Reply #5 on: April 20, 2017, 10:16:02 AM »

Hi Bill, for the most part you may be correct about that, but I have also noticed that saturation clipping can be non-negligible, so yes, useful to pay attention to both.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml

Doug Gray

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Re: Correcting out of gamma problems
« Reply #6 on: April 21, 2017, 03:55:06 PM »

Unlike monitors which are light emissive, gamut shrinkage is an intrinsic property of reflective media. Such media creates colors only through attenuation of spectral frequencies. Yellows are the least affected because high saturation yellows need only attenuate blues which contribute little to luminance.

The Sun's luminance, about 500,000,000 cd/m^2 when low in the sky like in the image, is about 5 orders of magnitude greater than the luminance of reflected light from surfaces on the Earth.

I can't offer a solution other than Photoshop manipulation and soft proofing to create the most attractive result.
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Rand47

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Re: Correcting out of gamma problems
« Reply #7 on: April 24, 2017, 07:09:26 PM »

This is assuming your image is showing soft proof gamut warning and not the regular clipping indicator in Lightroom DEV panel. 

According to Jeff Schewe, and others, the out of gamut warning in Lightroom isn't very helpful.  It doesn't tell you "how much" out of gamut you are.  Have you made a print to see how it looks re screen to print match?

Often in situations like your example I'll use perceptual rendering intent, and prints look fine re STP match. 

Rand
« Last Edit: April 24, 2017, 07:13:43 PM by Rand47 »
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Schewe

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Re: Correcting out of gamma problems
« Reply #8 on: April 25, 2017, 01:58:07 AM »

According to Jeff Schewe, and others, the out of gamut warning in Lightroom isn't very helpful.  It doesn't tell you "how much" out of gamut you are. 

I've never said it isn't helpful, I said it could be a lot better when it comes to showing how much a color may be out of gamut–which it doesn't do now. I have said that people should not fall in love with the OOG warning and certainly shouldn't ruin their images in a misguided attempt at getting their images completely in gamut.
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Rand47

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Re: Correcting out of gamma problems
« Reply #9 on: April 25, 2017, 10:44:56 AM »

I've never said it isn't helpful, I said it could be a lot better when it comes to showing how much a color may be out of gamut–which it doesn't do now. I have said that people should not fall in love with the OOG warning and certainly shouldn't ruin their images in a misguided attempt at getting their images completely in gamut.

Jeff,

Thanks for the fuller explanation.  Sorry to put words in your mouth.  I translated your statement in the soft proof video, "One of the things I'd like to disabuse people of is the notion that the gamut warning means anything useful, it doesn't." as, "not very helpful."  I should have been more precise. 

Rand
« Last Edit: April 25, 2017, 11:01:19 AM by Rand47 »
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