Watch video: How to use the LAB mode in Photoshop CC
Most of us will normally work on our Photoshop CC (opens in new tab) images in the RGB color mode. In this mode, each pixel is given a certain value for red, green and blue. These combine to create millions of colors. As such, RGB mode is the principal mode for most edits. But it does drawbacks… In RGB mode the color and brightness of your image is tied into one. Adjust the red, green or blue value of any pixel and, as well as changing the color, you’ll also affect brightness.
This is where LAB mode comes in. Like RGB, LAB is also an acronym. It stands for Lightness, A and B channels. These represent an entirely different set of values for each pixel. The Lightness values determine how bright the pixels are, while the A and B values set the color. Put simply, LAB Mode lets us edit color and brightness independently of one another – something that is harder to achieve in RGB mode.
Not only is this very useful for boosting color intensity and making images ‘pop’ with color, it’s also a very powerful means for changing colors completely.
In this tutorial we’ll look at how it’s done. First, we’ll enhance the colors in the image by squeezing the A and B color channels, which gives a powerful yet natural boost to the image. Once done, we’ll go on to enhance the contrast, control the effect with a mask, and experiment with color-changing shifts.
01 Switch to LAB(opens in new tab)
Open up your image or use our start file which can be downloaded here (opens in new tab). Go to Image > Mode > LAB Color. If your shot has a few layers, press Cmd / Ctrl + Shift + Alt + E to merge a copy of the layers, then right-click the layer and ‘Convert to Smart Object’. Double-click the Smart Object thumbnail to open it in a new window, then convert this to LAB.
02 Target the A Channel
Go to the Layers panel and click the Adjustment Layer icon. Choose Curves. Expand the Properties panel to display a large graph. Click on the channel dropdown (where it says Lightness) and choose A. This represents the green-magenta spectrum of colors.
03 Boost the greens(opens in new tab)
Drag the black and white arrows along the bottom of the graph in by equal amounts, ensuring the diagonal line intersects the centre of the graph (if it doesn’t stay over the centre, the colors will shift). The result is a powerful, natural-looking, boost to the greens.
04 Squeeze the B Channel(opens in new tab)
Next, go to the channel dropdown and choose the B channel. This controls the yellow-blue spectrum of colors. Repeat by dragging the arrows in (or, drag the top and bottom points on the curve line). The further inwards you drag, the stronger the boost in color.
05 Increase the contrast
The Lightness channel lets us change the luminance values in the image without affecting the colors. Drag a point near the top of the line upwards, and a second point downwards to boost the contrast with a shallow S-shaped curve.
06 Fine-tune with a mask
If you find parts of the shot look over-saturated you can reduce the effect by painting on the layer mask attached to the Curves layer. Highlight the mask thumbnail, grab the brush tool, set color to black and brush opacity to 20%, then paint to soften the effect.
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