A lot of people have problems with masking trees. All those leaves are a lot of work, they think.
I promise you I can show you how to do this in just 3 minutes and put a new background behind it along the way!
First we need 2 sources:
For the tree we use: http://www.sxc.hu/photo/1184924
and as a new background: http://www.sxc.hu/photo/1211288
Open up Photoshop and resize both images to the same width, we'll start working on the tree image.
We'll be using a tool which is hardly ever used: the "Background Eraser Tool".
On top you're able to change some settings:
1. take a nice big soft brush, I used one with a 2013 diameter
2. set the sampling to contigious
3. set limits to discontigious
4. the tolerance high: 40 (we can do this because the blue background behind the tree has a nice contrast with the green tree, if the contrast isn't that high you must set the tolerance lower)
5. check the Protect Foreground Color box
6. we've checked the Protect Foreground Color box so we must select a foreground color; click on the foreground color > the color Picker menu will open > now use the color picker to select an average green in the tree. This will protect this color and it will not be erased later on.
Now the funpart starts.
Because we use a big brush you'll probably just see the cross in the centre of that brush, that's OK because that's just what we need. Start clicking on the blue and you'll see all the blue disappear, do this also on the other colors which are left (some whites and other light colors.
Check between the leaves for some left over spots of blue and remove them the same way.
You'll be left with just the tree and the grass. To show you below there's twice the same tree, once a black background and once a white background.
If you just wanted to mask the tree: CONGRATS, YOU ARE DONE!
I'll add a new background to this as well, as a bonus ;)
Add the sky as a new layer below the tree.
If you look closely you'll there's still some white lines surrounding the leaves. That's why I'll show you as well on how to remove those.
In the layers pallette: select the layer with the tree and right click on it. A new menu will open and select "Blending Options" on top. This will open a new window.
All we are going to do is set the "Blend Mode" to "Darken Color" and click "OK"
There's some rubbish coming through the grass, just select your layer with the sky and gently erase them.
Now all you have to do is finetuning your image, use a smal soft blur brush and blur the edge of the grass and new sky (be sure you have checked the "Sample All Layers" box on top) and so on.
That wasn't that hard, was it?