Shadow Tints

Open a colour image from Lightroom in Photoshop.

1. Open the Layers tab
2. Select New Adjustment Layer icon.
3. Choose Black & White . . .

Black & White adjustment layer should now be immediately above the Background layer.

Adjust the Black & White adjustment layer sliders to maximise the monochrome effect.

1. Select the Channels tab.
2. Command + Click on the RGB Channel icon.

If you did the previous step correctly, you will have selected the image as indicated by the marching ants.
If not then repeat on the RGB channel.

Go Select > Inverse.
Note: this will invert the selection to mask the highlights istead of the shadows.

1. Open the Layers tab again.
2. Select New Adjustment Layer icon.
3. Choose Solid Color . . .

From the Solid Color palette, choose a colour for the shadow tint.

The colour now needs to be adjusted to maintain full tonality.

1. Change the Blend to Color.
2. Adjust the Opacity to about 20%.

The image will now have a tinted shadows colour without any colour in the highlights.