Layer Masks are your friend
When you work with multiple images, it’s usually tempting to go the ‘obvious’ route, and simply cut out what you need and paste it as a layer onto the second image:
Ten minutes later after some more manipulation work, I notice that I accidentally erased half of that poor gentleman’s coffee mug, and now no one will be able to appreciate his wry nerdy wit! It’s too late to undo, so my only choice is to recut him out of the original photo and drag him over again. Precious minutes, wasted.
Enter the layer mask!
Rather than just copying over the selection, we’ll copy the entire first photo over as a layer:
and then click this guy down here to create a layer mask:
Clicking this will give us that extra ‘layer’ to the right of our currently selected layer that is completely white. This is a layer mask.
Now, instead of cropping out parts of the photo, we’ll simply paint black on the layer mask. Make sure you have the white layer selected and your brush is set to black, and start painting away areas you don’t want to see:
Alright, that’s done. Oh no, it looks like I got rid of his mug again (I must be bad at this) However, it’s no problem, I can just paint over that area of the layer mask with white and it’ll be back!
Or, maybe I think he should have a ghost mug and it should be a little transparent. Anything you paint on a layer mask between white and black will be rendered partially transparent, so I can give my lego man a ghost mug:
So in the future, remember your good friend the layer mask and use him to your advantage. He’ll save you time and effort and let you make cooler effects quickly.