Automated Head swap

You can also try using Edit > Auto-Align Layers... to help with alignment.

sourabhverma 

What is you full workflow?  I'm wondering if you might be able to improve it a wee bit.

I'd prefer to keep the files separate to reduce confusion.  There are lots of ways to do this, but to make it easy.

Make an oversize selection of the new face with plenty of overlap.

Drag it to the master document, and position and scale by maybe reducing opacity temporarily.

Move the new face below the group layer and lock it's position.

Add layer mask to the group layer, and reveal the face below the layer.

Add a clipped curves layer between master and new face layer if you need to match brightness.

Note: you could also use Dodge or Burn on the new face layer, but make sure you select to appropriate tonal range in the options bar, or you can end up with a muddy mess.

I'm thinking this approach is flexible and simple.

Good luck

This is always going have to be done manual. I dont know how large the group is and therefore how much real estate each face takes up but try the face-aware liquify tool for small adjustments. For the others I would use the stamp tool to bring in the new face.

/G

Hi

I sometimes do this with larger wedding groups - take 2/3 shots and be prepared to swap heads on any that blinked. There is no quick way to do it convincingly though. Even with a camera on a tripod and a group that aren't moving there is small movement on each person. So the only convincing way is to identify any heads/faces which require the swap. Then for each head manually align the replacement by lowering opacity and aligning it with the existing image. Then raise opacity add a mask hiding "all" then unmask just enough to cover the issue. Sometimes this might just be the eyes - sometimes it might be head and shoulders it really depends on the differences. Even if the replacement heads are coming from the same second shot, each needs to be aligned individually. I would never attempt to automate this as the potential is for a mess through misalignment.

Dave