Fixing with Luminosity masks

Luminosity (Luminance) masks are an interesting tool. Consider the situation where you need to apply a fix to an image but the lighter portions of the image are ok, it’s the darks that aren’t – or vice versa.

Start by duplicating the image layer and apply the fix to the top layer. Concentrate on the portion of the image that needs fixing, ignore the disaster that’s happening in the areas that don’t need fixing.

When you have the fix in place, it’s time for the fun stuff. Locate a channel which has the detail you want for your mask. You need a channel that is dark where you want the fix to be less and light where you want it more (or vice versa, as you can invert the mask). When you have your channel, Control + Click on the channel (Command + Click on the Mac) to load it as a mask. Now go back to the image and add a mask to the layer – it is automatically created as a luminosity mask based on the channel you used. So, your new mask is white where the channel is light and dark where the channel is dark. Of course, if you need it in reverse, add your mask, select it and press Control + I to invert it. Where the mask is lighter, the fix is more strongly applied and where the mask is darker, the fix is least strongly applied.

In the image above, shot in Harajuku, Tokyo on New Year’s Day, I’ve used a Luminosity mask based on the image’s own red channel to add some extra contrast and colour to the wonderful hat. I duplicated the image layer and applied a simple Overlay blend mode to that layer. Then I added the Luminosity mask to force the fix into the areas lightest in the red channel – ie where the reds in the image are located and less so in areas which weren’t red. (If this sounds wrong to you, remember that in RGB mode, the red channel is lightest where red is located and darker where it isn’t, ditto the green channel – it’s lighter where the green is and darker where it isn’t, etc..)

There’s also a handy shortcut you can use to make your masks if you know which channel to use. Use Control + Alt + 1 for the Red channel in a RGB image, Control + Alt + 2 for the Green and Control + Alt + 3 for the Blue. In LAB, the same shortcuts will get you the L, a and b channels respectively.


Helen Bradley

I am an expatriate Australian lifestyle writer, videographer and photographer. I write tutorials and produce videos on Photoshop, Lightroom and Illustrator as well as photography, office computer applications and DIY crafts. I have written for most of the big names in consumer tech including PC World, PC […]

Topic Filter: Commercial / Landscape / Portrait / Stock / What's Hot

Related Tutorials


Martin Lawrence

After many years as a keen amateur photographer, I decided to start a small landscape photography business called Lakescenes which I ran alongside my main job as an IT Manager. As business increased, I found myself working long, but rewarding, hours just to keep up […]

Read More

Rob Sheppard

Rob Sheppard is a naturalist, nature photographer and videographer who says his favorite location is the one he is in at any time. He is the author/photographer of over 40 books, as well as a well-known speaker and workshop leader, and a Fellow with the […]

Read More

Gary Hart

Gary Hart has photographed California’s natural beauty for over 30 years. Gary’s photos and writing have appeared in many publications, most recently Outdoor Photographer and Sierra Heritage magazines. You’ll also find his images in greeting cards, postcards, calendars, and many galleries and private collections throughout the world.

Read More

Jaroslav Wieczorkiewicz

Originally from Poland, based in London UK, Jaroslav has background in Fine Arts, degree in Architecture, and wide array of experience. Being an Architect taught him how to be resourceful and to solve complex problems with simple, yet innovative solutions. Constant passion for graphic & […]

Read More

What's Hot

Beauty Lighting for Stills and Video

Trying New Things I definitely fall into the category of photographers who get bored doing the same thing over and over again. Although I am often hired to shoot a style that my clients see on my website or portfolio, or shoot images for a […]

Click to Watch

Taking Control of Contrast, Saturation and Sharpness

Taking Control of Contrast, Saturation and Sharpness is at the very heart of photography. When you shoot a photo on your camera one of two things happen. Either the camera saves the image as a Raw file or as a Jpeg. The fundamental difference between […]

Read More

Take your best ever Christmas photos

While the packed supermarkets, heaving shopping malls and congested traffic networks can try the patience of even the biggest Christmas fan, there is no doubt that this is a really magical time of year for the family photographer. Here are five ways to get your […]

Read More