Theres two ways that i would use to do this in photoshop:
1. Make selection from red channel
- Go to Channels window and click red channel while holdin Ctrl button to make selection out of it.
- Make sure youre back in rgb channel and go back to layers window.
- Copy the selection Ctrl+j and there you go.
You could also invert slection and delete the background.. Works either way.
1. Make it into a brush
- Turn the image black and white.
- Invert colors Ctrl+I to make sure that the image you want to extract is now black andbackground white.
- Then go to Edit > New brush preset and make the image into a brush.
- If you get brush tool you can find this image as a brush in the brush list.
Its good to keep in mind that when you make aa brush dark and light colors are threated as opacity essentially ( black = 100%, white = 0% )
Also this will only work on single color...
Will add better explanations tomorrow when im on my pc.