Quick guide to creating photoshop masks based on the original image. This is useful for lifting shadow areas where you didn’t have something like a fill-in flash but still have information in the shadow.
Take the image below as an example. Looks like the metering setting was wrong when the photo was taken – it seems too dark in the shadows but the sky and mid-tones look ok and don’t need to be brightened up.
I need to lift the shadows, especially under the roof of the watchtower, without washing-out the intensity of the sky color. Here’s where a mask based on the image can be used to good effect. I’m going to mask out the sky and try lifting the brightness of the rest of the photo. This won’t work, of course, if the camera hasn’t recorded any information in those shadows.
Firstly, I create a duplicate layer above the original image. It’s always a good idea to work with copies.
Working with this copy, I isloate the sky by using the magic wand on the blue -there’s a strong colour contrast between the sky an the rest of the image and it should work quite well. The tolerance is at 40, the selection is anti-aliased and to make sure I get the sky showing between the safety rails at the top, I uncheck the ‘contiguous’ option. Imperfections in the selection because of the largetolerance figure picks up some spots in the watchtower but I can easily deselect them.
Creating the mask
Once I’m happy with my selection of sky I create a new, empty layer to hold a mask image. At this point, my selection is still active but I’m now focussed on the new layer I’ve just created
To create the mask I use the fill tool to fill my selection in black. I make sure the ‘contiguous’ option is unchecked here, too, to be sure I fill all of my selected area in the new and currently empty layer.
Now, I need to copy this proto-mask into a real mask layer for the original image. I create a mask on the original image Select/All on the the mask preparation layer, copy it to the lipboard and then paste it into the newly created mask. The layers panel looks like this:
I switch off the mask preparation layer and then I’m free to adjust the shadows of the watchtower without worrying that I’ll washout the sky. Comparing the two images:
You’ll see the fire engine has more detail to it, the fire officers are wearing bright yellow jackets, and the detail under the roof of the watchtower is clearly visible.