04 Desaturate the layer
We don’t want any colour information in this layer because this will distort the colours in the final image once the effect’s been completed, so use the shift-ctrl/command-U shortcut to Desaturate the layer. It should now look like a black and white negative image.
05 Switch to overlay mode
This is where it starts to get interesting. Using the drop-down blend mode menu on the Layers palette, switch this top layer’s blend mode to overlay. What happens now is that the lighter parts of this layer will lighten corresponding areas on the layer below, while the darker parts will have a darkening effect.
Now we’re getting somewhere. The landscape is brighter and the sky is darker… but we’ve got the same problem we had with the Elements Shadows/Highlights dialog – the transitions are too sharp and the image looks unrealistic and ‘processed’. But the technique I’ve used means I can fix this very easily.
06 Blur the overlay layer
Remember what I was saying earlier, that Photoshop had Radius sliders to smooth the transitions? You can get the same effect here by blurring the top, ‘overlay’ layer you’ve just created. You can experiment with different amounts of blur, but the maximum value of 250 pixels often gives the best results. (Smaller blur amounts often leave visible ‘glow’ effects around object outlines.)