Boosting Contrast And Color With The Luminosity Mask
Free Adobe Photoshop Photo Editing Tutorials At Photoshop Essentials.com
Written by Steve Patterson, Photoshop Essentials.com
In this Photoshop photo editing tutorial, we're going to learn how to boost the contrast and color of an image using a little-known trick to select pixels based on their luminosity (lightness) values, which is officially known as "activating the luminosity mask". Once we have our selection, we're going to combine it with a layer blend mode to add more life to the image and give it a bit more visual snap.
Here's the image I'll be using for this tutorial. At the moment, the image is looking a little flat and the colors are a bit dull:
Here's how it will look when we're done:
Let's get started.
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Step 1: Ctrl/Cmd-Click On The RGB Channel To Create A Luminosity-Based Selection
The first thing I'm going to do is switch over to my Channels palette, which is grouped in beside the Layers palette:
Since my image is using the RGB color mode, and yours most likely is as well, the Channels palette is showing me my Red, Green and Blue channels. It's also showing me what appears to be a fourth channel at the top named "RGB", but it's not really a channel. It's just the composite of the Red, Green and Blue channels. If all this talk of channels is beyond your current Photoshop skill level, don't worry. You don't need to understand them for what we're doing here.
All you need to know is that to select pixels based on their luminosity values, simply hold down your Ctrl (Win) / Command (Mac) key and click anywhere on the RGB channel in the Channels palette. I'm going to click directly on the thumbnail, but you can click anywhere on the RGB channel:
Once you've clicked on the RGB channel, you'll see a rather crazy looking selection inside your image, as I have here:
What's happened is that Photoshop has gone through the image and selected pixels based on how bright they are. Pixels that are pure white are selected 100%. Pixels that are pure black are not selected at all, and pixels that fall somewhere between white and black are partially selected at a percentage based on how close they are to white. In other words, what we've just done is selected the lightest parts of the image.