New Tutorial on Saturation Masks

[gmitchel]

“Expose to the right” is a popular refrain among digital photographers these days. Follow the advice, and you can end up with pictures that have a clipped channel. No highlight warning. The histogram does not indicate a problem, either. It's only when you get back and load your images into your RAW converter that you learn about the clipped channel.

Saturation masks allow you to make smooth saturation adjustments in order to bring back some highlight detail from the precipice and reeestablish smoother tonal transitions. You can also use their inverse to boost muted colors without oversaturating portions of the image that already have saturated colors. Read my new tutorial, "Restore Those Clipped Channels," to learn how to use saturation masks in your color correction.


http://www.thelightsright.com/DigitalDarkroom/Tutorials.htm#RestoreClippedChannelsTutorial


My TLR Saturation Mask action set makes it easy to generate saturation masks.


http://www.thelightsright.com/DigitalDarkroom/PhotoshopTools.htm#TLRSaturationMask


Cheers,

Mitch


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[CyberDyneSystems]

Awesome tutorial.. thanks for posting this! :)

[gmitchel]

I'm pleased you found it to be a helpful technique. :)

Cheers,

Mitch

[Jesper]

Thanks for your valuable technique! :)

It's well known that if you overexpose with a digital camera to the point that the image is blown out, you can forget about repairing the image, because the information simply isn't there.

But after trying your technique on one of my own flower photos (with a red and yellow tulip, in which the red channel was overexposed), I was amazed at how much detail I could get back in the yellow parts.

[gmitchel]

Thanks for your valuable technique! :)

It's well known that if you overexpose with a digital camera to the point that the image is blown out, you can forget about repairing the image, because the information simply isn't there.

But after trying your technique on one of my own flower photos (with a red and yellow tulip, in which the red channel was overexposed), I was amazed at how much detail I could get back in the yellow parts.

Yep. If you completely burn out data, i.e. take the value to 255, there is nothing to be done.

What often happens is the highlights get compressed. Some clip completely. So just get very close to 255. By using a saturation mask, you progressively affect those pixels with high values. You can affect them more than other values, lowering them and spreading them out more.

I refer to it as "pulling information back from the precipice." A cheesy metaphor, but I think it conveys the idea.

I'm pleased you found the technique helpful.

Cheers,

Mitch

[slejhamer]

I understand how to make the mask, but not how (or where) to apply it. The PDF does not seem to include this step. Do I save it as an alpha channel? Copy the luma channel from the mask? Apply it to a hue/sat layer? I can make it work, but I'm not at all sure I'm doing it correctly. Please help.

[Jesper]

I understand how to make the mask, but not how (or where) to apply it. The PDF does not seem to include this step. Do I save it as an alpha channel? Copy the luma channel from the mask? Apply it to a hue/sat layer? I can make it work, but I'm not at all sure I'm doing it correctly. Please help.
Yes, the tutorial is a bit brief about what to do with the saturation mask once you've made it... This is what you can do:

Copy the background layer, add a layer mask to the new layer (one of those little icons in the bottom of the Layers palette), select the saturation mask (click on the saturation mask layer and do Select All), copy it to the clipboard (Ctrl + C). Then make the layer mask active by Alt + clicking on it and do paste (Ctrl + V) to paste the saturation mask into the layer mask.

Now the copy of the background layer has the saturation mask as a layer mask, and you can tweak the saturation and lightness with the Hue/Saturation adjustment.

[slejhamer]

Excellent, Jesper. That's a good way to use it, and it seems those follow-up steps can be easily added to the action with a stop for the hue/sat adjustment. Thanks!

And Mitch, thanks for posting this useful tool!

[gmitchel]

Soory the article was light on what to do. I'll add some more text. Thanks for the suggestion.

I'm glad you found the technique to be helpful.

Cheers,

Mitch

[gmitchel]

I revised the action set to make both high saturation and low saturation masks.

The high saturation mask is the original. The low saturation mask is just the inverse.

The article was revised to describe how to use the low saturation mask to boost muted colors while not oversaturating other image features. Sample images were added, too.

Cheers,

Mitch

[slejhamer]

Thanks for this update! The low-sat mask looks to be very useful as well.

:)

[Belmondo]

I'm already thinking of a bunch of shots I want to try that on. Thanks very much.