Photoshop CC 2019
1. My base image. This is the third in the series, so I'm using the same model's face across all three. This meant, when I started this process, I had to make sure there was a wide selection of head angles for this particular model.
2. I start out using a low-res comp image to make sure I can get the placement and angle right. If I can't get it to work and look JUST RIGHT, the final product is going to be a mess.
3. Satisfied with placement, I downloaded the high-res model face. Since I used smart objects, all I had to do was open the SO for the face, paste in the updated image, and voila.
4. Threshold adjustment layer. Using this, drag the slider slowly from one side to the other. This shows you where the darkest and lightest parts of the images are. Obviously, if the face is showing up as darker or lighter than the rest of the image, then it needs to be fixed. I clipped a levels adjustment layer to the face, lowered the highlights, and brightened the darkest parts. (Image: with threshold layer enabled, showing that the face is much brighter than the rest of the body.)
5. After levels have been adjusted.
6. Color Fill adjustment layer. Choose any SUPER BRIGHT color. Set this layer to "Hue" blend mode. See picture: notice how the face is a lot more saturated than the body? That means the saturation of face and model isn't matching.
7. Clipped a Hue/Saturation adjustment layer to the face and lowered the saturation until the two matched. Disabled the Color Fill layer. Pictured is the result.
8. Curves Adjustment Layer, clipped to the face. This is a hard one to explain in words. On your curves properties, see the little eyedroppers? This represents your highlights, lowlights, and midtones. Make sure the Curves layer is selected NOT the mask), pick the white eyedropper and double-click. A color picker window will come up. ON THE BODY, select the LIGHTEST point you can find. In this case, it's a spot on her shoulder. Click okay. (If it asks "Save the new target colors as defaults?" Select NO.) Now, on the face, find the brightest point and click once. This will match that highlight color to the highlight of the body.
Now, do this with the lowlights, too. The midtones can be the hardest. You want to try to find a section of skin color that is as close to the middle of black and white as possible. Click around and see where it pops up on your color picker chart. When you're satisfied, hit okay, and now try to click around on the face and find a midtone that matches. Sometimes you might get REALLY funky results--that's okay. Keep clicking along the most middle-toned areas and eventually you'll find a good match.
9. Go back to your Color Fill layer and re-enable it. Set blend mode to Saturation. This is a FANTASTIC way to see if your colors are matching up. This image shows what it looked like BEFORE step 8, and then how it looks AFTER step 8. With our Curves adjustment alone, we got really close in color on this one. Sometimes, there's still some more work to be done. When that happens, I use a Selective Color or a Curves adjustment layer to tweak a little until it looks right.
10. Obviously, the lighting isn't quite right on this new face. I'm throwing another Curves layer on the face, dropping the brightness pretty far down, and then hitting ctrl+I (PC keyboard) to invert the mask and make it all invisible. Now, using a white, soft round brush with the flow set to around 20% (opacity at 100%), I start to paint in areas that need to be darkened. In this case, I painted in around her cheek and jaw. If you're stuck on what areas need to be painted, disable your face layer and see how the original model's face was lighted and try to emulate that.
11. Repeat step 10, except instead of going dark on the Curves layer, go lighter. Again, invert the layer mask, and paint in where you want the highlights. I often make the areas around the eyes, nose, and mouth a bit brighter because you want it to be the focus point of the person. Doesn't have to be majorly drastic, of course! Also on this layer, I right-clicked and went to the "blend if" sliders, messing with them to make sure the highlights weren't affecting the darkest parts of where I painted. (Such as inside her mouth, nostrils, irises, etc.)
12. I'm fairly happy with this, but just eyeballing it, the face still looked a tiny bit too yellow compared to the body. I threw a Selective Color adjustment layer on the face, switched to "Neutrals" in the dropdown, and upped the Magenta slider by about +7. Now I think I'm happy with it!
Last is the final version of the cover. I did a fair bit of painting, largely with the rim lighting, her lips, and hair. The great thing about using this method of smart objects and adjustment layers is (and I did this several times) that I can go back at any time and make further tweaks as I progress and notice something is still off. In this case, I noticed the highlights I added to her face with my curves adjustment layer were too extreme, so I toned them back down.