Good practices for sky enhancement?

On some occasions and light situations the sky gets a bit dull, too bright and grey in my photos.
Formerly I was using a tonecurve on the L channel to bring down parts of the sky and increase contrast. But this didn’t improve the color situation there.

After researching in various tutorials around the web I found a way of sky enhancing using the ‘colorize’ module with a ‘multiply’ blend mode. The steps to reproduce:

  • Add colorize module
  • Saturation: 0
  • Lightness: 100%
  • Source mix: 0%

Now there should be just a white area

  • Blend: parametric Mask
  • Blend mode: multiply

And now’s the original image back.

To prepare the effect we should restrict the module to the sky. A parametric mask that only selects the brighter part of the image is a good start, maybe it should be complemented with a drawn mask.

Once you’ve found a mask that only selects the sky you can continue:
Bring down the lightness to around 50-60%.
Now the sky might look a bit dull since you may have reduced its contrast. In this case it can be a good idea to decrease the effect’s amount in the highlights (see the parametric mask in the screenshot below).

Experiment with the lightness parameter of the module and the upper boundary range to find a good compromise for the sky’s lightness and contrast.
Moreover you can try the ‘mask contrast’ slider to adjust the effect.

Now let’s go for the colors:

  • Select a hue somewhere in the blue area
  • Add saturation

Experiment with both sliders to find the right color and saturation.

Example:

With this method I’ve got control over contrast and color cast in one module. I compared it with using a tone curve with LAB independent channels. The ‘mask contrast’ and ‘lightness’ sliders give me a more fine control of the cloud details than the tonecurve on the L channel.
Moreover the color controls with hue and saturation are easier to control in the colorize module.

@TheStoryOfRico recently made a video about working on the sky using hazeremoval and local contrast:

Haze removal didn’t work in my photo, but local contrast enhanced it a lot (although it takes down your saturation):

What are your thoughts and practices? Other ideas and methods I’ve overseen?

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Blend mode ‘subtract’ makes the effect of the ‘colorize’ module more intense and gives more contrast.

Haze removal algorithms generally ignore (bright) skies.

I used to do this with the tone curve L, then saturate the blues using tone curve B.

Now I use the color zone module, darkten the blue luminance and raise the blue saturation. I also apply a gradient mask if necessary.

I do this way too. Less fancy, very fast. Pity in 2.7 it is set to “strong” by default, which creates weired artefacts.

Theres a preset in channel mixer to increase color contrast. This can be used in combination with an appropriate mask to bring out blue skies like using a polarizing filter.

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What about adding clarity with the equalizer (so the clouds look nicer)?

Big fan of experimenting with blend modes in the modules…its not often presented to new users and it has dramatic affects…in some images I use sharpen with multiply and then draw the opacity down to 10-20% …gives a nice enhancement …often try this when dehaze fails …conversely I have used a simple linear tone curve of modestly tweaked with either multiply or screen to darken or lighten and image and with the ability to tweak it with opacity it can also be effective…

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Always shooting with polarizing filters on all my lenses, except when I can’t afford to lose 1.3 stops, I never had to care about bringing the skies back (it’s actually sometimes the opposite).

As a general rule, you need to recall that bright colours can’t be very saturated as well (limits of colour spaces gamut), so the first thing to do would be to pull down the lightness. Then you can add more saturation (but is it sane ?).

I would just use an exposure module blended in multiply mode with 20% opacity there (poor-man dodge & burn) with a drawn mask to isolate the sky, then a little bit of local contrast, and be done.

The problem I see with your methods based on (Lab) colorize module is they make the sky look way sharper than the rest, which is not very natural (almost as if the sky was taken from another picture).

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I agree that just for bringing back an overexposed sky the exposure module is most effective. However, I do not complicate things with blend modes. I just pull down the exposure slider and limit the effect with a parametric mask to the sky. First I exclude everything but the blues in the H channel, then, if necessary, I exclude the dark colors in the L channel.

Thanks for your input. I tested your method with the exposure module and found out the results look more natural than with the colorize module.
To increase colors I used the color zones module with the same mask as in exposure.
Seems like the blend mode is the key, with blend mode ‘normal’ I don’t get a satisfying contrast.

This and:

Blue%20sky%202

plus saturation with Velvia module:

Color look up table also works very well:

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