Five tips for painless tones shifts
Method 2: Split Tones with Curves
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Use this technique when you want to add two different tones—one for highlights and one for shadows. Make a Curves Adjustment layer and set its blend mode to Color. Then use the pulldown menu to choose the Blue Channel rather than RGB. Make a subtle S-curve, lifting the shadows and pulling down the highlights. This will bring a blue tone into your shadows and blue’s opposite, yellow, into your highlights.