Layer Masks
Skill level: Intermediate
Programs used: Photoshop 6
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| Layer masks are a useful tool in photoshop, as they can achieve
many different effects, but with added "insurance" against any
setbacks; you don't have to delete the image in the layer, just hide some
of it. |
Blending images using layer masks
If you have two images which you want to blend into each other seamlessly,
this can easily be done using layer masks. For best results make sure your
2 images have the same amount of dots per inch. The standard is 72 dpi.
Take note, this will not make each image seperate in it's blending, but
make both images equally viewable.
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1. Create a new canvas, which will comfortably fit both images into it
without having any transparency around the borders. Paste these two images
into the new canvas. It doesn't matter which one is on the top. Now in the
layers palette, make sure your top layer is activated, and press the "Add
a mask" button  .
This will activate a layer mask, enabling you to edit which parts of the
image will show, and which parts won't. |
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2. Now select the gradient tool, and select the gradient type to be linear,
black to white. Now click on the white square in the layer mask to make
sure you are working on the layer mask. A white stroke will appear around
the white square, indicating that the layer mask is activated (in the above
layers palette, the white stroke is around the image, while in the below
image, the mask is active). |
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3. Now draw a straight line gradient from anywhere to anywhere on your
canvas, and notice how the white square displays the gradient you just
drew:
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| However, the image itself shows both pictures. The areas in which the
gradient was black has disappeared on the top image to reveal the bottom
image. |
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| You can also try different types of gradients to achieve different effects,
such as the radial gradient over a pattern below: |
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Cropping without deleting
I'm sure it's happened to you once, you've spent a lot of time cropping
an image, only to realise you've made a mistake somewhere, and you need
to re-crop the image. Too bad you deleted it when you cropped it the usual
way :(
But using a layer mask, it's simple to go back to the original image after
having cropped it. Here's how: |
1. Activate the layer which you want cropped, and select the polygonal
lasso tool  .
Make a selection of everything you want to keep. |
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| 2. Now simply press the "Add a mask" button
and your image will be cropped straight away. There you have it, a cropping
of your image, but you can easily re-crop it if you make a mistake, by right
clicking on the mask and choosing to "Discard Layer Mask"! |
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Also try turning off the link 
between the image and the mask to be able to move the image around inside
the mask!
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