This is a short trick that demos how to reposition a layer in Photoshop and create a perfect match.

Maybe you sometimes encouter this problem: You like to make some changes to a copy of a image and then position that copy exactly back in the scene where is was before.

Hmmm - does anyone get the problem?

Okay! I try to point it out.

I like to use the liquefy filter on the girls body. But instead of working on the complete layer, I like to work only on a small part of it to save memory and have a smaler file to work with and gain some processing speed.

First I chose the shape tool from the toolbar and select the custom shape tool.
The custom shape tool comes with a variety of deault shapes in a popup list, one of this shapes is a registermark.
You ever wonder what to to with it? - let me show you.

I select the registermark shape and draw the vector path of the registermark to a place in the image where it's good to see and didn't cause problems for the further work.

It doesn't even matter where you draw the registermark exactly, it comes on its own layer and you can reposition it later to a place you prefer.

After the registermark is placed I dublicate the image to do the changes on the duplicate and not the original file.

I delete all the layers I don't need and crop the image to the part I like to work on

Open the liquefy filter and do some liquefying to the girls body.

Afer the changes are done I bring the modified layer back into the original file.

Now the registermark's comes in handy because I have to place the modiefied layer exactly to it's old position to match perfectly.

But this is no big deal because the old layer and the new modiefied layer have the registermark and to bring them together perfectly on top of each other is no problem at all.

After the two Layers are positioned I can merge them together and erase the registermark from the layer.

Thats all - a handy little trick, I think.