Layer Mask

Clive R. Haynes FRPS

Go through the following exercise to begin to understand Layer Mask.

Open an image with a single (Background) Layer.

Select (Marquee/Lasso) a portion of the image.

Edit / Copy > Edit / Paste

The selected/copied area has appeared on a new layer.

Use the 'Move' tool and re-position the copy image (upper layer) so you'll be able to see the effects of your work.

Make certain that the upper layer is activated.

A Layer Mask may be created in two ways

1. By clicking on the Layer Mask icon (white circle within a grey square) at the bottom of the Layers palette
2. Via, Layer > Add Layer Mask > Reveal All (more about the 'Hide All' option later)

As soon as the Layer Mask is created, the layer window will have two rectangles - one for the image (thumbnail) and one for the Layer Mask area thumbnail ( a white, 'empty' space). Notice the link symbol between the two. For most purposes keep this visible (clicking on it will remove the link). The link ensures that the image and its Layer Mask are locked together so that should the image be moved, the mask will follow it.

NB Make certain you recognise which icon is which. Look at the icon to the right of the 'eye' icon in the layers pallette, now, do this:

a) Click in the image rectangle (thumbnail) of the active layer and the Layer Mask (grey square with a white central circle) icon changes to a brush icon

b) Click in the Layer Mask rectangle and it changes back again to show the Layer Mask icon .

This is important - painting on the Layer Mask needs to be done with the Mask icon visible, whilst work on the image itself must be done when the Brush icon is visible.

Activate the layer containing both the image and the Layer Mask.

Make certain that the Foreground and Background colours (bottom l.h. of toolbox) are respectively black and white.

Choose either the airbrush or the paintbrush and a reasonable brush diameter (so you can see what's happening).

With the brush pressure/opacity at 100% paint in and around the image. You will see that the image is stripped away to reveal the layer beneath. Swap the foreground colour to white (a short cut for this is to press the 'X' key). Paint over a section that you've just erased. Magic, the brush paints it back again.

You can change between black and white paint to erase and restore as often as you like with different opacities/pressures and brush sizes.

You now have the use of a very powerful tool at your disposal enabling you to seamlessly meld images together.

Should you forget to click on the rectangle containing the Layer Mask to activate the Layer Mask icon, you'll paint black (or white) paint on your image - we've all done it! Thankfully it's easy to undo and carry on.

Should you wish to work on a specific area within the mask and not stray beyond, you can do this by simply making a selection ('inverse' it if you wish) and work away - painting on the mask will stop at the selection edge.