This is a very basic tutorial showing the most effective way to make a face mash using photoshop.
Step 1: Choose the faces.
Perhaps the most important step in making a face mash is choosing the original images to work from. The critical thing is that the faces are orientated in the same approximate way. Below you can see an example of a bad choice of faces to mash.
If these faces were mashed it would look very unnatural because features would be orientated in the wrong direction. Below you can see an example of a good choice of faces to mash.
Notice how the faces are both turned slightly towards the right. Another thing to consider when choosing pictures is lighting. If one picture has heavy shadows it may be difficult to blend with the other image. Colours and size are not an issue as they can be fixed relatively easily in photoshop. These pictures appear to be very similar in lighting so they will probably work well.
Step 2: Match the faces.
There is a very simple method to get the faces to the same size and position. First, copy and paste both faces into the same image file in photoshop. The larger image should be on the upper layer. Now make sure the upper layer is selected and in the layers palette select the Opacity tab as shown below.
Bring it down to around 50%. You will now be able to see both images overlapping.
With the upper layer still selected press (command-T) to enter Free Transform mode. Now grab a corner of the image and holding SHIFT scale the face down so that it is the same size as the other one. You can click inside the image to slide it around. If necessary, click outside of the box and drag to rotate the face. The goal here is to line up as many features as possible. Use the eyes as a guide. If the eyes match up and you chose your images well the rest of the features should match up as well.
Now bring the layer opacity back up to 100%.
Step 3: Erase.
Select the eraser tool. Make sure the brush hardness is at 0% so that the edges of the eraser are soft. The first thing you can do is eraser all the extra space around the head. In this case the hair from the face behind appears.
Because of this it might be a good idea to use the hair of the lower face because it would be difficult to remove otherwise, although in some situations it may be possible to blend both hair styles together.
Here all the hair has been erased on the top layer. Now decide which other features to erase from the top face. The trick is to erase just enough so that both faces are apparent but also create a new face at the same time. In this image below the eyes have been erased.
The face now looks like a new person but with careful attention both the sources can be identified. You may wish to experiment with which features you erase. It can make a big difference so feel free to go back a few steps and try a different combination of facial features.
Step 4: Balancing colours and light.
You will notice in the image above that the skin colour around the eyes is a bit different from the rest of the face. This can be fixed. Go to Image –> Adjustments –> Colour Balance…
Now play around with the sliders until the colours match up more effectively. You may also need to adjust the brightness and contrast to blend the images.
Another trick to blend the faces is to use the eraser tool with an opacity of around 30% and go over the edges of the areas where the two faces meet. This will create a smoother transition between any kind of tonal discrepancies.
Here you can see the faces have been balanced.
That’s about all there is to it. If the lighting in the two images is considerably different it may be necessary to perform additional manipulations but this one looks done.
That is the end of this tutorial. If you have any questions or feel something was missed please add a comment.