Masking Images in Photoshop.

1/. Find three images which could be masked together. In this example - a house, a fire and a tree.

2/. Resize the images so they are proportioned, to the appropriate size. The background should be large.

The final image used here is a cottage, with a fire out front and a tree.

1/. A cottage 2/. A fire 3/. A tree 4/. The finished image.

The full sized images are linked to the thumbs above.

This is how it is all done in Photoshop using layers and a layer mask.

1/. Open the background image.

2/. Open the next two images.

3/. Copy/paste the two images to the same file as the background, ensuring the background image is the bottom layer. If layers are not shown, Window/Layers turn on the layers.

4/. Select all the layers - Shift/Click, so they are highlighted.

5/. Edit/Auto-Blend Layers and use the settings - Stack Images and Seamless Tones and Colours.

 

Here's a more complex example, that requires a lot of background removal on the image:

A desert scene A ship (with a lot of background removed - using the eraser) A fire The result

Here's another example:

Take a forest Add a fire Add a train, twice, with the second image rotated The result