In the following steps, you'll take the top image and turn it into the bottom image by repeating the bald fellow's head. The trick is to match the angle of each of the heads you're covering, and to accomplish that, you'll make use of the Quick Mask mode.

1. Open 9_expert.jpeg from your exercise folder. (You can also download the above image from your browser.)

2. Use the lasso tool to select the woman's face. As I'm sure you remember, when cloning over elements in Adobe Photoshop, you always want to start by selecting the element that you want to replace, and then using that selection outline to grab the replacement item. This makes it easier to match one element to the other.

   Don't try to draw an accurate selection--just rough it out by Option/Alt-clicking around the head. Go ahead and select a bit of the white area around the hair, and include the first row of pearls. Better to select too much than too little.

3. Switch to the Quick Mask mode. As shown below, a red coating covers the deselected areas, while the selected head remains altogether exposed.

Prepare selection for cloning

1. Reset the colors in the toolbar. Press D, then press X. This makes the foreground color white and the background color black. This way, you can adjust the area of selection--which is white in Adobe Photoshop's mind--without leaving white holes in the background. Instead, the holes turn black, ensuring that they remain deselected.

2. Select all of the transparent area revealing the woman's face--don't even try to create an accurate selection. Select as much red overlay as you want--you can even use the marquee tool.

Transparent window in front of woman's face is selected with marquee tool

3. With the move tool, drag the selection to the left, so it's roughly centered on the bald guy's face. The figure below shows what I mean. Notice that the selection doesn't leave behind any hole; this is because black is the background color.
   
   Selection moved left

4. Make sure the Info palette is visible. Choose Window>>Show Info if it is not. You'll need to refer to it in the next few steps.

5. Now we're going to rotate the selection so it is aligned with the tilt of the bald guy's head. Choose Layer>>Free Transform. Then drag outside the marquee to rotate it. Drag inside the marquee to move it. For the best result, the angle value should fall somewhere between 12 and 16 degrees, as in the figure below. When you finish, note the angle value in the Info palette. Press Return/Enter to complete the rotation.

Rotated selection

Replace woman's head with man's
We're almost done.

1. If necessary, nudge the selection with the arrow keys to center it on the fellow's head. The selection may look fine without nudging.

2. Press the Q to exit the Quick Mask mode. The red overlay goes away, and marching ants surround the guy's head.

3. Option/Alt-drag with the move tool (or Cmd-Option-drag/Ctrl-Alt-drag with any other tool) to clone the man's face so it covers up the woman's face. You don't have to position the selection exactly. Roughly is good enough.

4. Choose Layer>>Transform>>Numeric (Cmd/Ctrl-Shift-T). This command lets you rotate the selection by a numerical amount. Enter the value you noted from above--in my case, I got a value of - 14.5.

5. Nudge the selection into place with the arrow keys. It may help to press the 5 key to lower the Opacity of the floating selection to 50 percent. This way, you can see the floating bald guy and the woman underneath.

6. Now let's rescale the guy's head proportionately to the woman. The top of his dome should align with the top of her hair, while the base of his neck should meet with her pearls. I recommend stretching the head only slightly. Press Cmd/Ctrl-T to invoke the Free Transform command, then drag the bottom handle down until the H value in the Info palette reads 106.5% (or thereabouts). Press Return/Enter to complete the resizing.

7. Restore the Opacity to 100 percent. Once the bald man is precisely positioned so his head aligns with the top of the woman's hair, press the 0 key.

8. Press Cmd/Ctrl-D to deselect and drop the selection. Now the bald guy is glued in place.

The finishing touches
From here you can refine the effect as much as you like. I recommend Option/Alt-dragging with the eraser tool to revert the image to its last saved appearance, just to make the effect even more convincing. A retouched image is displayed below:

Final effects