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LAB Mode A/B Channel Stepping

Adding Saturation Without Adding Chroma Noise.

I love saturated colors, but just moving the saturation slider can add a lot of Chroma Noise to your image. Here is a simple technique for adding saturation to an image without adding any chroma noise.

The secret to this is using Lab Mode.

Let start with this image... Interesting image... but could use some POP in the color.
labstep_starting_image.jpg


1) <image><mode><LAB Color>
This converts our image from RGB to LAB. Instead of a Red Green and Blue channels, we now have Luminosity, A and B (LAB) channels.

The Luminosity channel has all the bright and dark info on our image. The a and b channels store all of the color information.

LAB mode is VERY VERY VERY useful to the photographer as we will learn in other tutorials.

2) <Layer><New Adjustment Layer><Curves>

Leave the Luminosity Channel alone.

On the A Channel, move the top square about 10% to the left. Move the bottom square about 10% to the right.

Your curve should look like this:
labstep_a_curve.jpg


Switch over to the B Channel and do the exact same thing.

Your curve should look like this:
labstep_b_curve.jpg


3) Adjust the opacity of this layer to your taste.

4) <Layer><Flatten Image> (Always flatten your layers before you switch from LAB to RGB)

5) <Image><Mode><RGB Color> - Convert back to RGB Mode

Here is our final result.
labstep_final_image.jpg
 
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