[Updated April 2017]
Luminosity mask is an incredibly powerful image editing tool in Photoshop. It allows you to make a selection specific to the area you want in your image.
This technique becomes even more versatile with the introduction of the new infinity mask recently.
If you’re new to photography, you might be wondering:
What’s the big deal about selection tool?
Well, a good image is about applying the right amount of adjustments in the right place.
Having a robust editing tool enables you to achieve that efficiently. In general, luminosity mask delivers results, saves time, saves you from getting frustrated and makes post-processing more enjoyable.
By the end of this tutorial, you’ll learn how to create and apply luminosity mask in Photoshop, how to use it to apply basic tonal and color adjustment, and the pitfalls.
This is a long post (5290 words). If you’re in a rush, download the PDF and read it at your own leisure!
What This Tutorial Is Not About
This tutorial is NOT written to teach you the technical aspect of using luminosity mask (e.g. exposure blending). It’s quite impossible to cover everything under the sun on the application of luminosity mask in one single post.
If you’re looking for an in-depth tutorial on how to post-process with luminosity mask, check out the tutorial on exposure blending, tonal and color adjustment. You can find more of these on the sidebar of this page.
Think Your Images Are Flat and Dull?
Ever felt your images are stale and your post-processing is repetitive?
Are you looking for a way to distinguish your images from the others?
Enter luminosity mask, or luminance mask – how most professional photographers (especially landscape) use to post-process their images.
I can almost feel your heartbeat and heavy breaths already 😉
Take Control of Tonal and Colour Balance
Luminosity mask helps you create highly specific and targeted selection. The applications include exposure blending, local adjustments and more!
Many photographers use this in their post-processing workflow and so should you.
But there’s something you need to do first…
Layer Masking Is The Foundation
Yes, layer mask in Photoshop.
It’s fundamental and you MUST know it before you proceed.
Everything about luminosity mask builds on the basis of layer masking. This is because it’s essentially a layer mask.
So, make sure you take your time to learn and understand how it works before hand.
Fortunately, it’s not a difficult subject to learn.
If you don’t know layer mask yet or simply want to refresh your memory, watch the official video tutorial on layer masking by Adobe.
It’s a selection tool based on the luminosity value of the image.
Once the selection is made, it is then applied as a layer mask to conceal or reveal part of the image.
It was first published by Tony Kuyper in 2006 and has since been adopted by photographers in their workflow.
I know you probably have ONE question now:
What is luminosity value?
Luminosity = Brightness
So, to sum it up, it’s the brightness of the pixel.
A pixel is the building block of an image. Thousands and millions of pixels of different color make up an image.
Every pixel in an image has a luminosity value (0-100%). This determines how bright or dark it is.
The different level of brightness in each pixel determines if it’s being selected or not, based on the type of luminosity mask you choose. (I’ll explain further below)
Making A Selection Based On The Brightness of The Pixels
Unlike other selection tools in Photoshop, luminosity mask allows you to create a targeted selection with more natural feathering.
Have you tried making a selection of the sky and you just couldn’t get it all selected properly? There’s always a part that gets left out or an unwanted part gets included.
With luminosity mask, this becomes less of an issue.
Where can you use luminosity mask in post-processing?
The truth is:
You can use it any way you want.
In fact, I encourage you to experiment with it and try to think outside the box once you understand the principle.
But for the purpose of the basics, there are 2 ways to apply this technique:
- Exposure blending
- Targeted local tonal and color adjustment
As the name implies, it involves merging images of the same frame taken at different exposure together.
In photography, the process of merging exposure is called blending.
Images are often blended together to create a high dynamic range (HDR) image.
Learn more: The Ultimate Guide To HDR Photography.
I know what you’re thinking:
Aren’t there HDR software to do that already?
You’re absolutely right, there are plenty! But some photographers don’t like the so-called “HDR effect” created by HDR software. The images are typically oversaturated and unnatural looking.
The main advantage of blending over HDR software is that you can decide how you want to blend the images.
With luminosity mask, you have more control and flexibility over the blending process.
The final blended image is often thought to be cleaner and more natural, especially among nature photographers.
Learn more: The Ultimate Guide To Exposure Blending.
Targeted Local Adjustments
Have you ever applied a Curves adjustment in Photoshop but only want to affect the sky?
This typically involves making a selection of the sky using one of Photoshop’s selection tools. It takes time depending on the complexity of your image. You might have to re-do the selection a few times and your final adjustment might still not look natural.
You’re not alone, we have all been there 🙂
It’s frustrating, demoralizing and makes you question your post-processing skills.
With luminosity mask, making a selection can never be easier. It’s quick, more precise and with feathering. This means your adjustment blends in more naturally.
There will be times when the area can be over selected, but there are ways to deal with that.
In terms of software, all you need is Adobe Photoshop. With the current Adobe Creative Cloud (CC), you pay a low month subscription fee and get both Photoshop and Lightroom under the photography bundle. You can get a free trial here.
Personally, I think it’s good value as it’s highly affordable and you get any latest update downloaded instantaneously.
Another software that works with luminosity mask is GIMP. You can find out more information here.
There are many free and premium plugins available that generate the mask automatically for you. Most plugins also come with other useful tools for post-processing. The links to these plugins are provided in the coming section below.
One thing you need to know is that:
It’s not a tool you can choose from the menu.
Luminosity mask live in the hidden place called the channels panel. By default, Photoshop generates 3 color based luminosity mask for every image: red, green and blue.
As you can see, our selection is going to be pretty restricted if we were to use the default mask. So, we need to create more variations.
To help you understand the fundamentals, I’ll go through the process of creating the mask later on.
The Brights, Darks and Midtones Luminosity Mask
A set of luminosity masks targets all 3 main zones of an image: the highlights, the shadows and the midtones.
These are often called brights, darks and midtones masks.
Similar to a layer mask, white reveals, black conceals and gray partially reveals or conceals depending on the luminosity value.
Creating a set of luminosity masks manually takes time, and you wouldn’t enjoy spending 5-10 minutes creating it for every image.
Here’s the solution:
Automation! Yes, it’s about working smart and efficiently.
So, here are a few ways to get that automation process for yourself:
- Create it yourself once, record it and save it as a Photoshop actions. You can then automate the process the next time you need it.
- Download the luminosity mask Photoshop Actions here for free.
- Download one of the free Photoshop luminosity mask plugin which I’ll explain below.
For the purpose of this tutorial, I’ll go through the steps for creating the mask manually.
Alternatively, you can watch the video below too 🙂
Creating Luminosity Mask Manually
You’re going to use the channels panel, rather than the layers panel that you normally work in.
I use a Mac, so bear in mind that Cmd = Ctrl in a PC and Opt = Alt. Remember to save it as Photoshop Actions so you don’t have to repeat this painful process again.
- Open your image in Photoshop.
- Go to the channels panel.
- Cmd + click on RGB and save the selection as a new channel by clicking the little button at the bottom of the channels panel that looks exactly like the layer mask icon.
- Now you should see the new channel saved as alpha 1.
- Without deselecting, hold down shift + cmd + opt and click on alpha 1 to intersect the selection.
- Again, save it as a new channel by clicking the little button at the bottom. You should now see it saved as alpha 2.
- Repeat step 5 and 6 until you reach alpha 6.
- Now rename all alpha 1-6 to brights 1-6. These are your luminosity masks for highlights.
- Now deselect the selection by holding cmd + D. We’re now going to create the dark masks (which are the inverse of brights masks).
- Cmd + click on brights 1, inverse the selection by shift + cmd + I. Save this as a new channel by clicking the little button at the bottom again.
- You should see it saved as alpha 1 (this is because you have renamed the previous alpha 1 to brights 1. Don’t worry about the name as you are going to rename it later).
- Repeat step 9 and 10 on brights 2-6 until you arrive at alpha 6.
- Now rename the new alpha 1-6 to darks 1-6. These are your luminosity masks for shadows.
- Cmd + D to deselect everything. Now we need to subtract shadows from the brights to create the midtones masks.
- Cmd + click on brights 1, then cmd + opt + click on darks 1 to subtract it.
- Save the selection as a new channel by clicking the little button below. It will be saved as alpha 1 (again, don’t worry about the name).
- Repeat step 15-16 for brights 2 and darks 2, brights 3 and darks 3 until you arrive at alpha 6.
- Rename all new alpha 1-6 to midtones 1-6. These are your luminosity masks for midtones.
If you prefer a more visual learning style, check out this video on how to create luminosity mask in Photoshop.
Luminosity Mask Panel
These are created by photographers for photographers.
Besides creating the basics, each luminosity mask panel offers different features and other tools for post-processing. You can check them out to see which you prefer.
These are all FREE.
Each of them also has a premium version which offers more advanced features.
- Luminosity mask starter kit by Tony Kuyper
- The easy panel by Jimmy McIntyre
- Luminosity masking actions for Photoshop by Greg Benz
- Interactive luminosity mask by Sven Stork
- ADPpanel Mini by Aaron Dowling
Once you have downloaded the installation file, just follow the manual to install it.
You should be able to use it right away in Photoshop. It doesn’t matter which one you use, you will be able to create the same 18 luminosity masks in the channels panel.
The fundamentals of luminosity mask are exactly the same as layer mask:
- Black = Completely conceals.
- Grey = Gives the layer different levels of transparency depending on the amount of gray there is.
- White = Completely reveals.
- A layer mask only affects the layer it applies to. This means the layer directly below it.
3 Important Rules of Luminosity Mask
For the purpose of this tutorial, let’s say a set of luminosity mask has 18 masks (6 brights, 6 darks and 6 midtones):
- Bright masks – The brightest areas are in white, less bright areas are in different shades of gray and the shadows are in black. The selected area becomes less from brights 1 to brights 6.
- Dark masks – The darkest areas are in white, less dark areas are in different shades of gray and the highlights are in black. The selected area becomes less from darks 1 to darks 6.
- Midtones masks – All masks are filled with different shades of gray. The shades of gray become less from midtones 1 to midtones 6.
You’ve probably noticed. The rules above are exactly the same as for layer mask.
Luminosity mask is a way of creating a layer mask. The advantage of it over other selection tools in Photoshop is its ability to make highly targeted and customizable selection.
Once you have the selection you need, you can then apply any adjustments to it.
This video shows you the basics of luminosity mask and how it creates a selection.
Now that you understood what is luminosity mask and how to create them, it’s time to dive into some action!
I’ll show you the 2 main applications of luminosity mask in this tutorial:
- Digital exposure blending
- Targeted local adjustment
Exposure blending is a post-processing technique to blend images of different exposure together.
Its aim is to extend the dynamic range and balancing the tonal values. You can blend two images or more to create an HDR image.
It may take longer than using an HDR software but the results are often more satisfying.
And what’s more:
Exposure blending stimulates your creativity and allows you to have total control of your image.
To give you an example, I’m going to use the image of the Pantheon in Rome I took.
The Pantheon has an incredible architecture and I felt tiny just by standing at the bottom of one of the pillars.
Shoot Multiple Exposure To Cover The Whole Dynamic Range
In this image, I’ve exposed for the foreground (the buildings), which left the background (the sky) to be overexposed.
This is because the dynamic range of the scene had exceeded what my camera can capture. Exposure bracketing was necessary to include the full dynamic range of the scene.
Even though the shadows between the pillars seem dark, I know from the histogram that there’s no shadows clipping and I can recover details during post-processing.
I’ve also taken another image to expose for the background (the sky), which left the foreground (the buildings) to be underexposed.
The aim here is to blend both images together using luminosity mask.
Create Luminosity Mask For The Base Image
Here’s what I did:
I opened both images in Photoshop. I used the first image as the base image to create the luminosity mask.
My aim was to replace the overexposed sky with the sky in the second image. Because the area I wanted to replace was bright, I needed to use a bright mask that targets the sky.
With a single click, I created 18 luminosity mask without having cramps in my fingers. (thanks to the Photoshop actions!)
These were the 6 bright masks in the channels panel. I wanted to pick one that has most of the sky selected (in white).
I also wanted to exclude the buildings from my selection, so I want the buildings to be in black (or darker shades of grey).
Looking through the bright masks, I thought Bright 2 or 3 were the most suitable ones. I picked Bright 2 in this case.
There Is No Right or Wrong On Which Mask To Use
Trial and error is often the key to success in blending and post-processing in general.
I encourage you to experiment with different mask to see which gives the best result you like.
Here’s what I did:
- Place the first image as the first layer and the second image as the second layer.
- Align the images by going to Edit > Auto-Align Layers. I did this because I shot the bracketed exposure handheld.
- Create a layer mask and fill it with black on the second image to mask everything. So now you should only see the first image because the second image is now invisible.
- Cmd + click to select Bright 2 luminosity mask from the Channels Panel and then click on the layer mask on the second image in the Layers Panel. You should now see the marching ants, which means selection from the luminosity mask you selected is now applied.
- Now select the brush tool, set the size to large and hardness to 0 (you want a large, soft brush). Make sure the foreground is set to white and start painting the layer mask in the sky to reveal the sky in the second image (top layer).
- If you find the marching ants annoying (which I often do), cmd + H to hide them. The selection will still be there but you won’t see the dotted line running around.
There are certainly other ways to blend images and this is one way to do it.
This is a straightforward example of how to blend images with luminosity mask. Sometimes you might need to blend more than 2 exposures to create an HDR image.
But this is not all to blending with luminosity mask.
There are other advanced blending techniques with luminosity mask. I have provided some useful links at the end of this tutorial if you like to learn more.
Another way of using luminosity mask is to apply adjustments in targeted areas on a single image.
Before you start,
I highly recommend you to use a RAW or TIFF file instead of a JPEG because of bit depth.
This is because you want the highest number of colors available to avoid posterization.
Just to recap:
Luminosity mask creates a highly targeted selection with seamless feathered transition.
This simply cannot be replicated with other selection tools in Photoshop.
I’ll use this image below to show you how to apply tonal adjustments with luminosity mask.
It was taken near midday so the image looks flat and washout in general.
Let’s bring this image to live!
Creating Luminosity Mask
I can sense you see a routine here.
Everything starts with “creating luminosity mask”.
Applying adjustments through a luminosity mask
These are the layers that I’ve applied to the image. Let’s go through it together.
- Layer 0 : I double clicked the background image to convert it to a layer.
- Layer 1: Curves adjustment layer applied to a Brights 2 to reduce the highlights.
- Layer 2: Levels adjustment layer applied to Darks 6 to brighten the shadows of the cactus.
- Layer 3: Curves adjustment layer applied to Brights 3 to reduce the highlights further. I changed the blend mode to multiply to fine tune the effect.
- Layer 4: Curves adjustment layer applied to Midtones 2 to bring up the overall contrast with a S-shaped curve. I changed the blend mode to luminosity to preserve the color saturation.
- Layer 5: Vibrance adjustment layer to boost the overall color.
- Layer 6 & 7: Dodge and burn with various brights and darks masks targeting only the clouds and the shadows of the cactus.
- Layer 8 & 9: Overall dodge and burn to create a vignette.
Here’s the before and the after.
Subtle Transformation of Your Image
The adjustments are subtle but it does make the image pop.
That’s the advantage of post-processing with luminosity mask.
You tease out the best of every pixel to make an overall effect on the image.
Let me show you one more thing:
If you look at the top right-hand corner (the deep blue sky), the tone and color have not changed because it was protected by luminosity masks.
This wouldn’t be possible if we’ve applied the adjustments globally. Even with layer masking, the transition still wouldn’t be as smooth and subtle.
Even though it can create a better selection, there are limitations to it.
But don’t you worry.
There are ways to deal with these common pitfalls!
In this tutorial, I’ll highlight a few that you may encounter during your workflow.
A pain and an unsightly problem.
Here’s the solution:
A better understanding of light.
This is caused by a significant difference in the brightness of each bracketed image.
The interval between the bracketed exposure is too wide and there isn’t enough tonal information to fill in the gap. This typically happens in high contrast scenes like this.
It was in the evening but the sun was still very bright. I spotted an interesting rock formation and used it to frame the sun. I’ve bracketed 3 exposure as below.
As you can see, the brightness in the +2EV is greater than the brightness in the 0EV and the -2EV.
There is a big gap between the brightest and the darkest image, and there is only 1 image in between for tonal transition.
What could I have done?
Take bracketed exposures at a closer interval to ease the transition from the dark to the bright.
In this case, 5 or even 7 bracketed images may have helped to reduce or even avoided the halos.
It seems intuitive.
Reduce highlights with a brights mask and brighten shadows with a darks mask.
But it doesn’t work that way for the shadows.
Why is that?
If you see the luminance mask on the far left below (Darks 2), the whitest part falls on the darkest area of the rock.
This means the darkest shadows are all selected.
And the problem:
If you brighten that up, all the shadows, including the darkest shadow will be brightened. This will cause the image to lose overall contrast and becoming flat.
Use A Dark Mask To Subtract The Darker Masks
You want to brighten the shadows yet maintain the contrast.
And if you think about it:
Contrast is when there is a difference in the darks and the brights. This means preserving the darkest shadows (maybe you can brighten it up a little) while brightening the less (or least) darker shadows.
To do that, select a dark mask and subtract the darker masks following it to preserve the darkest shadows.
Dark or bright edges sometimes occur when you try to blend images with high contrast together (it’s always high contrast that’s causing the problem!).
It often appears on the outlines such as tree branch (in this case), rocks or mountains. It’s actually not easy to spot them without zooming into the image.
If you can’t see it, why do you need to fix it?
This is because if you print your image large, it will show up in an obvious way and ruin your print. On the other hand, fixing it only takes a few minutes and there’s no reason not to do it 🙂
In this example, you can see the edges of the blue sky painted over the tree branch on the right.
On the left, it did the opposite, leaving a white edge between the blue sky and the tree branch.
The way to fix it:
Reverse select and paint over it. I’ll explain.
Fix Edging With Reverse Selection
To fix the white line on the left, select the magic wand tool in Photoshop.
Set the tolerance to 15 (in this case) and make a selection of the tree branch.
Now, modify the selection by going to Select > Modify > Contract, and retract the edge of the selection by 1 pixel to exclude the white line from the selection (2 or 3 pixels if you have a thicker white line). Inverse the selection so that the sky and the white line are now selected instead.
The next step is easy.
Select the brush tool, changed the foreground color to the color of the sky by opt/alt + click on the sky and paint it over the white line.
For the over-painted area on the right, do the same except select the sky first and inverse the selection after.
The inverse selection method can be used in any situations where edging is present.
There will be times when even the most suitable luminosity mask doesn’t make the selection you need.
The mask can either over-select (including areas that you don’t want) or under-select (not including areas that you want).
So, what can we do about it?
Here are a few tips to help you refine a mask or create a custom mask for your selection.
- Add or subtract luminosity masks. You can combine multiple masks together or subtract one from others. To do that, cmd/ctrl + click on a luminosity mask, then add other masks by holding down shift + cmd/ctrl + click. You can add as many masks as you want. Opt/alt + cmd/ctrl + click to exclude a mask from your selection if needed.
- Right click on the mask in the layers panel and select refine mask. Select the view mode to black and white and use the adjustments below to refine your mask. Very straight forward.
- Click on an empty layer mask in the layers panel, go to Select > Color Range. At the bottom of the panel, change the selection preview to grayscale so that you can see the changes directly on your image. You can play with the fuzziness to refine your selection, or you can pick a color from the drop-down menu. To sample a color, use the eyedropper tool on the right and click on the area in the image that you want to select. You can add or subtract selection by using the + or – eyedropper tool. This creates a color based mask instead of a tonal based mask. This means the luminosity mask is based on the shades of the color rather than the brightness.
It’s a head scratcher in blending.
If you’re using an HDR software, you can use de-ghost to fix the problem.
But we don’t have that luxury in blending, not yet.
How does ghosting look like?
If ghosting is not strong or only affecting the image minimally, you can reduce the opacity of the layer or use the clone stamp tool or healing brush to fix it.
But that’s not an option in this case.
The solution here is:
Double Processing A Single Raw Image
No, I don’t mean editing the image in both Photoshop and Lightroom. 🙂
It’s a post-processing technique where you take a single Raw image and make a duplicate copy.
You brighten up the shadows in one and darkening the highlights in the other, and you blend both together. In this case, with luminosity mask.
I know what you’re thinking.
Why can’t we brighten up the shadows and darken the highlights in the Raw image?
Remember the greatest strength of luminosity mask is also its weakness. The tonal adjustments will bleed over into the shadows and the highlights.
If you do it separately in 2 images, you don’t have to worry about that because you’re going to blend it.
Shadows that are brightened up in the highlights priority image will be recovered by the shadows priority image during blending and vice versa.
Now, because only a single image is used, you wouldn’t have a problem with ghosting!
Luminosity mask is a huge topic and it’s impossible to cover the details of using the mask in a single post.
I hope you’ve learned the fundamentals of luminosity mask and what you can achieve with it.
If you like more tutorials related to luminosity mask, you can find them in the “Related Posts” on the sidebar navigation menu.
Watching videos is often the easiest way to learn for some (certainly for me).
There aren’t many video courses that cover luminosity masking extensively. Having said that, these two video courses are probably the best there is on the market at the moment.
I have watched them both and I can honestly say that these are of high quality in terms of content and value. Both are excellent resources that focus on a slightly different aspect of luminosity mask in post-processing.
Alternatively, search “luminosity mask youtube” and you’ll find plenty of short tutorials.
The Art of Digital Blending
If you want to learn more about luminosity mask and take it to the next level, I highly recommend The Art of Digital Blending by Jimmy McIntyre.
There are 11 videos that come with JPEG files for you to practice as you go along. Each video is concise and straight to the point.
Besides covering the basics of luminosity mask in great detail, you’ll also learn how to blend in 6 different scenarios. It comes with a PDF of the entire course.
You can read my full review on The Art of Digital Blending here.
The Complete Guide To Luminosity Masks
Another awesome video course is the Complete Guide to Luminosity Masks, 2nd Edition by Sean Bagshaw. This video course focuses entirely on luminosity mask only.
Each video is much longer and dives deep into the topic. At the end of the course, you’ll learn both the basic and advanced use of luminosity mask in post-processing.
I hope you’ve learned the fundamentals of luminosity masking.
If you’re still feeling confused, try An Idiot’s Guide To Luminosity Masks where everything is broken down into small chunks of simplified explanations.
It does take some time understand the concept. The key to successfully mastering this technique is to have plenty of practice!
So, download the Photoshop Actions or a panel now and start experimenting with it today!
Once you start using it to post-process your images, I promise you’ll see a difference in result.