Apr 27 2009
In Adobe Photoshop CS3, a new feature was added called Auto-Blend Layers. Its intent was to simplify the processes of stitching together overlapping layers… a photo of a sky to one of a landscape, parts of a panorama… those sorts of things.
Try this: start by positioning two of the layers and select both of them in the Layers palette (click the name of one in the Layers palette and hold down the Command key (Mac) or Ctrl key (PC) as you click the name of the second layer):
Now go under the Edit menu and select Auto-Blend Layers. Photoshop will interpret the overlapping pixels of the two selected layers and will attempt to blend them appropriately. It will also create a Layer Mask as well as sort of average the brightess and hue of the layers in order to make them blend.
It’s by no means perfect, but it’s pretty impressive for the lack of work you have to put into it.
If you’d like to blend another layer into a couple of layers you have already blended, its a good idea to merge the first two blended layers beforehand. If this is not done, the Layer Masks that Auto-Blend Layers creates can start to show edges. With the two blended layers selected in the Layers Palette, choose Merge Layers from the Layers palette’s flyout menu (Command-E on the Mac or Ctrl-E on the PC).
Then the procedure is exactly the same to blend addtional layers.
Okay, that’s the mundane usage of Auto-Blend Layers, but the fun way to use it is to take pictures of your friends to create a single visage. Here’s a somehwat unflattering face I made from my friends from The Lab with Leo Laporte:
The parts I used from the four pictures of the Lab cast goofing around were Kate Abraham’s forehead, Ryan Yewell’s nose and mouth, and Matt Harris’ eyes blended onto Sean Carruthers’ head.
Like I said, the way the function works is that it blends only the parts of the two images that overlap. You only want to have enough overlap area for the the images to blend nicely: too much and you may have more facial features being blended in or blended away than you intended, too little and the blend may be too abrupt.
To illustrate how to blend faces, I’ve taken a picture of Andy Walker and made a tight selection around his face and deleted it. Next I’ve grabbed a picture of Leo Laporte and loosely selected his face and pasted it over the hole I left in Andy. I’ve made sure as I position Leo’s face that the pixels overlap the image below at least a little. (The first image below shows the relationship of the two source image layers: one with a small section being deleted, the other with a small section remaining)
Then it’s just a matter of going to the Edit menu and choosing Auto-Blend Layers. Boom! It’s done.