Editor’s Note: Don’t miss this week’s free event on when to jump from Lightroom to Photoshop.
Photoshop Luminance Masks are a great way to edit an image targeting just the areas you want. These masks aren’t solid black and whites but mirror the luminance values of a channel or channels. Lets jump into Photoshop and see how its done;
For this post Im using the image The Bride by anastasiyaand at Fotolia.
Using the Photoshop Workspace of Essentials or Photography you’ll find Channels grouped with the Layers and Paths panels. If youre using your own workspace without Channels then you can open the panel by going to; Window > Channels
Channels look like Layers but actually hold the luminance values of each or the red, green and blue channels. Where the channel is lightest is where more of that colour is added. To see each channel individually, click on it anywhere but its thumbnail
No surprise then that in this example the red channel is quite bright on the brides skin;
Selecting The Channel Luminance
To select the luminance of the channel take the mouse over the thumbnail of the channel and press Ctrl (PC) or Cmd (Mac);
Adding To The Selection
With all selection tools in Photoshop there are a couple of Modifier Keys. Pressing Shift will add to a selection while Alt (PC) or Option (Mac) will subtract from it. Selecting luminance values is no different.
You don’t need to stick to the same channel. Adding luminance values from different channels can make for interesting selections and results.
Using The Selection
Once you have the selection you want you can use it in any way you would use any other selection. In this example Ive selected the luminance of the Blue channel and then chosen a Selective Color Adjustment Layer.
I added a little yellow into the Neutrals to add a little warmth.
As you can see, a couple of steps can yield some dramatic effects.
A little while ago I did a video on Luminance masks at TipSquirrel.com.