Exposure Blending With Luminosity Masks

By YPLuminosity masks, Tutorials

I still remember, many years back, I was taking photos of the Inverness Castle with my Canon Ixus 400 (one of the earliest digital camera!).

An elderly man came to me and ask if I “photoshop” my images.

I felt insulted and replied instantly: “No I don’t, and never will”.

He smiled and said that sooner or later, I will.

I didn’t believe him back then.

And now here I am writing a tutorial on exposure blending with luminosity masks in Photoshop.

Alright…

This has nothing to do with this tutorial but it just came to my mind and I thought I’ll share it. 🙂

Exposure blending with luminosity masks is probably THE most used post-processing technique for landscape photographers.

It just makes sense, and I’ll explain.

 

Luminosity Masks

You can find EVERYTHING you need to know about luminosity masks in: The Kickstarter’s Guide To Luminosity Mask.

For the purpose of this tutorial, I’ll explain it in brief.

It’s a way of making a selection in your image based on the luminosity value of the pixels. A technique first pioneered by a photographer called Tony Kuyper.

The benefit of luminosity masks is the precise and quantitative method of making the selection.

But that’s not it.

The self-feathering nature of the masks is probably what makes it so likable by photographers.

Finding Luminosity Masks

First of all:

It’s not a standard tool you can select from the menu.

It’s in the Channels Panel in Photoshop.

Almost everyone who uses this technique has a Photoshop Action or a panel that creates the masks automatically.

Click here to download the Photoshop Action for luminosity masks for free.

 

 

Exposure Blending With Luminosity Masks

Personally, I prefer to blend with luminosity masks because it works for me every time.

I often shoot into the sunlight and I like to include the flares to add energy to my image.

Without luminosity masks, it would be extremely time consuming and challenging to blend in the flares from the darker exposure.

To get the best result, some planning ahead is necessary.

Blending with luminosity masks can essentially be broken down into 3 steps:

  1. Planning for multiple exposures
  2. Choose the right luminosity mask
  3. Blending in the exposure

 

#Step 1: Planning For Multiple Exposure

Every exposure blending requires a bit of planning before hand, this is no exception for blending with luminosity masks.

What does it mean?

It means you should always shoot with post-processing in mind.

Decide which part of the image needs blending in from a darker or brighter exposure.

Commonly, the sky will need a darker exposure to blend in. Also, consider foreground elements because it can often get underexposed.

The histogram is your best friend here!

 

#Step 2: Choose The Right Luminosity Mask

Before you start…

You should stack your images in layers and choose an image as the base image.

“Which should be the base image?”

I normally use the image exposed for foreground or one that requires the least area to blend in.

exposure blending with luminosity masks
In this example, I’ve chosen the image exposed for the foreground as my based image.

Use An Image With Good Contrast To Create Luminosity Masks

Again, you need to pick an image to generate the masks.

“Which one?”

Before I explain further, remember that luminosity masks are created based on the luminosity value of the pixels in the image you use to create the masks.

So, to answer the question:

Choose an image that has good contrast. In the example above, you can use either.

This is because both images have good tonal separation for the sky and the foreground. When the masks are created, there will be one that targets the sky, which includes the flares fairly well.

Increase Tonal Separation With Levels Or Curves Adjustment Tool

If the sky and the foreground have similar tonal range, the luminosity masks targeting the sky may bleed over into the foreground.

This defeats the benefit of using luminosity masks.

But there’s a way to get around this.

You can add a Levels or Curves adjustment layer to increase the contrast so that the darks become darker and the brights become brighter.

Create luminosity masks with the new tonal values and delete the Levels or Curves adjustment layer after.

Problem solved! 🙂

levels to increase tonal separation
Increase contrast with Curves or Levels for better tonal separation

Choose A Luminosity Mask Targeting The Highlights

Choosing the right luminosity mask will help you blend in the darker or brighter exposure more smoothly.

Going back to our image above, we want to blend in the darker exposure for the sky.

So, we need to choose a brights mask targeting the sky and the flares only.

We may not find the perfect mask but one that’s close enough will be just fine.

choosing a brights luminosity mask

Looking through the brights mask, brights 4, 5 and 6 are definitely out.

They are too restrictive and the flares are being cut out.

So, the question is:

Which would you choose, brights 1, 2 or 3?

Brights 1 includes the foreground, which means the darker exposure may bleed into it.

That’s not a big issue.

Because we can use “painting a mask” technique (see Learn More on tonal adjustment with luminosity masks).

Brights 2 looks about right, but is it too restrictive for the sun flare?

Keep On Experimenting Is the Key To Success With Luminosity Masks

The thing about luminosity masks is that it never has a definite answer.

You have to experiment with a different mask and see the effect yourself.

In the image above, I used brights 1 to blend in the darker exposure in the sky. I used “painting a mask” technique to restrict the effect to the sky and the transitional zone only. I left the foreground as it is.

 

 

#Step 3: Blending In The Exposure

Once you’ve found a mask to use, the rest is pretty simple.

You can either load the mask directly onto the layer mask, which will blend in the exposure for you straight away.

Or…

Use the “painting a mask” technique.

I prefer the latter because it gives me more control over the blended effect.

 

Conclusion

Exposure blending with luminosity masks gives you the control and flexibility that you need in digital blending.

The keys to good results are:

  • Choosing an image with good tonal separation to generate luminosity masks.
  • Choosing a luminosity mask that targets the selection you need to blend.

 

Learn More

 

  • Neil Hobbs

    Some great articles here, I am still trying to get my head around luminosity masking. One problem that really bugs me with your website is that I can’t use spacebar or page down buttons, you have to click in the scroll bar to move the page down. Please try & fix this, much nicer to use keyboard to scroll 🙂

    • Hi Neil, thanks for the feedback 🙂 I haven’t done anything to disable scrolling with the spacebar. Is it a browser specific issue? I shall look into that.

      • Neil Hobbs

        I’ve tried on 2 PCs, win10 with Chrome, win7 with IE7 both the same