Okay, here's a quick tutorial in Photoshop – I'll call it the "hollow man" tute.

We start with a studio shot of a posed shirt, taken for a catalogue. It's okay, but it's not amazing, and a graphic designer, not to mention the design agency client, will want it to look a lot better, even at an inch and a half high in a retail catalogue. So here we go. First step – remove the background.

We've chosen to deep-etch with a path and use that path to create a clipping mask. Go to your paths window (Windows>Paths if it's not available on your windows palette). Create a new path. Using the pen tool, draw a path around the edge of the shirt. As this is apparel feel free to smooth out some of the bumpier edges, but always err on the side of the t-shirt rather than the background. Once the path is complete, click the Make Selection button (the marching-ants icon at the bottom of the Paths window). I like to duplicate (Command-J for juplicate) the etched layer onto a new layer and hide the background layer in case I need it later, but feel free to use a layer mask (click the Layer Mask button at the bottom of the Layers window) on a floating layer (if the background layer says Background in italics, you'll need to double-click it first to make it float).

Next, we duplicate a section of the front of the shirt, place it over the area around the collar. Using the selection tool, select a rough square from the front of the shirt, avoiding the worst of the folds. Hit Command-J for juplicate (creating a new layer with just that section of shirt), and Command-T for Transform. Move the square piece of material over the collar area, being sure to cover the whole section to be filled. Hide the new layer.

We then create a new layer mask to drop that piece of material into the back of the shirt. I have a trick for this - use the direct selection tool to create the selection from which we'll make the layer mask. It won't be perfectly accurate - yet. Feather the selection by one or two pixels (Command-R). Select the new layer with the square of material on it, make it visible, and create a layer mask as we did before. If we look closely the edges will be a little weird. We fix this by selecting the masking layer, and using the dodge and burn tools to massage the edges to where we need them. If we find that our dodge and burn work is making our edge look a little sharp we can use the blur tool on the problem area, then go back to dodge and burn.

Once we're happy with our layer mask we need to use shadowing to give the image believable visual depth. To do this we create new layers, using the 'Multiply' setting (use the drop-down menu in the Layers window, which is by default set to 'Normal'), and duplicate the collar area layer mask onto each layer (easiest way to do this is to click and drag the layer mask with the option key held down). Using the paintbrush tool we draw black shadows over the new back of the shirt to give it the right amount of depth. Play with the transparency factor until it looks real - you'll find this setting at the top right of the Layers window (here I've used 66%). Feel free to create multiple layers to allow for more control.

Although I haven't found it necessary here, you may decide that you need to add an adjustment layer. Click on the Adjustment Layer button at the bottom of the Layers window, and add whatever adjustment you feel you might need. Don't forget to add the layer mask (click and drag from the layer below) so that the adjustment applies only to the inside of the shirt and not to the outside.

Finally, we drop in the label either from supplied artwork or, as in this case, from a different shirt. (I used the selection tool, feathered the selection by one pixel, and just copy/pasted to a new layer).

And there we go. Meet the hollow man.