How to paste one person's face over another

How to paste one person's face over another - an amateur's guide to a common Photoshopping, or in this case, GIMPing activity

Have you just got GIMP and fell like doing something useful with it? Need some quick 'n' E-Z blackmail material on someone? Simple! Just get a slightly blurry picture of them, download some slightly blurry pr0n, then copy 'n' paste their face over the faces of fornicating men/women/both! Thing is, it always looks fake, even if you use grayscale to make it harder to spot. It does. Come on. Well, this is basically an outline (nothing more!) of a slightly better way of doing it, with some (hopefully) helpful pointers.

I'm using GIMP for this, in case you want to copy along at home.¹ You should be able to do similar stuff in your own imaging software, but if not, just download GIMP. I'll be using:

• Free-Hand Selection
• Clone
• Transform
• Rotate
• Scale
• Flip
• Convolve
• Smudge
• Noisify

1. Fruan says: "re How to paste one person's face over another: You may want to add that a good zeroth step is finding two images where the head posing is at least passably similar. It saves manipulation later." He's right, you know.
2. Get your source picture, with your target's ugly mush. I used Free-Hand Selection tool for this. Draw using this tool, carefully, around the face. You want to cut out all of their face, perhaps a tiny bit of the background behind them, and make sure that the bit you cut out looks like a face, with no jagged edges. If there is a jagged edge, trace around the face again, or use the Clone tool to smooth it out.
3. Get your destination picture. Paste the cut-out face onto it. It's probably the wrong size, and pointing up or down too much. Use the magical 4-in-1 Transform tool for this. Rotate, Scale, Rotate, Scale. Repeat this until your cut out face just about covers the original face (but not much bigger than that).
4. Make sure that the face seems to be looking in the right direction (i.e. they don't seem to be doing the neck thing from The Exorcist). This can be a bit tricky to do sometimes, unless you use a program which can simulate turning an image in 3-D space, unlike most programs which only work on a 2D plane (for obvious reasons). Flip is a good tool for this.
5. Convert the image to grayscale. This makes it harder to spot your handiwork.
6. The perimeter of the cut-out face may well seem too sharp and clearly defined to be realistic, especially if the picture is zoomed in on. To solve this, use Convolve and run it over the edge of it. Instant blurriness!
7. The fake should be starting to take shape. If the neck colour seems too different from the facial colour, don't make the rookie mistake of just painting over it in the same colour as the face - just Smudge the part where they join.
8. If, when you zoom in, the perimeter of the face looks too blurry to seem real, then Convolve around the rest of the picture, but not too much.
9. The original picture probably has a tiny bit of noise in it. This can help cover up your tracks. Free-Hand Select around the cut-out face, then use the right-click menu to add some noise - use Noisify on a setting of about 0.02. Then do the same thing to the whole picture.

¹Don't drag me into that stupid GIMP is better than Photoshop pissing contest, 'cuz they're just as good as each other in their own way.