One of the hardest things to make look natural when removing or changing an image background from a portrait is the hair. If you only use the standard photoshop tools and techniques, you’ll end up with results that look obviously fake or clipped.
Take the image below of a woman on a green screen backdrop. You’d think this would be easy, right? That’s what green screening is for after all.
But, using the Photoshop background eraser tool really gives you a ragged edge, especially around any whispy strands of hair.
Using the select and mask filter is smoother, but no matter how you adjust the parameters, you’ll get a lot of green tint left over, and lose a lot of the finer hair strands.
What I have found to work best (and just as important, fastest) is to rough block out the area to isolate and then clean up the edging.
Start by drawing a path, using the pen tool, around the area to isolate the person. Be sure to include any medium to large locks of hair that stand out.
Once the path is completed, convert the path to a selection and save as a new layer. When you turn off the background (original image) you’ll end up with an picture that has some obvious clipped and discolored edges. That’s OK, because these will be easy to smooth out and fix.
First, lock the transparency of the image layer. Then, using a medium sized paint brush (about 50 pixels), set the paint mode to “color” and select a lighter color from around the edge. Then begin painting the edge to remove any green color cast. Sample for surrounding colors as you work, painting out the green tinted edging on the hair and any skin or clothing with a matching color. You’ll quickly be able to clean out the green edge tint.
Then, unlock the layer transparency, and using a 2 pixel smudge tool set to “darken” mode, lightly draw in the missing strands and whisps of hair by pulling them out from the existing areas of hair. Using the “darken” mode will prevent you from pulling any transparency back into the hair. Be sure to follow the natural direction of the hair… flowing your additions into place.
I use a Wacom tablet when doing this. With the transfer set to pen pressure, it’s easy to draw in faint strands of hair. If you don’t have access to a tablet or an iPad with an Apple pencil that can be used as a drawing tablet you can get the same effect by varying the opacity setting as you work.
Next, I will use a 2 pixel paint brush to add in any whips of hair that can’t be pulled out using the smudge tool. On this picture, that included the areas on the model’s left shirt sleeve and shoulder. Painting those in very faintly will make the final image with new background (in this case white, but it works on any backdrop color or image replacement) fit more naturally.
Finally, I will use the “defringe” command under “Layer / Matting” set for 2 pixels to subtly blend the image into the new backdrop. Flatten the image, and you’ll see a more natural looking effect of the model’s hair on the new background.
Senior Art & IT Director