Photoshop Chroma Key Green Spill Correction

There are several ways to extract an image from a green screen backdrop in Photoshop. You will want to use a method that leaves detail in the hair as shown in this image. Good techniques for this include the background eraser or color range selection tool. These tools will allow you to save detail in the hair. These tools will work with 256 levels of transparency based on the image color. This will ensure fine detail in the hair when the image is extracted. See the videos below for demonstrations of the background eraser tool and the color range tool.

DO NOT USE the magic wand tool, magic eraser, standard eraser, lasso, magnetic lasso, pen tool, or any other selection tool for making an extraction from a chroma key image. These tool can be tedious to use and provide inferior results. The selections made with these tool are "hard" selections for the most part. Yes, you can feather the selections, however the feathering is based on the selection path and not on the image color detail. If you want a good extraction.........stay away from these tools!

After the image is extracted, it is easiest to see flaws with a solid layer placed behind the image. I like to use a solid gray background with RGB values of 128, 128, 128 (50% brightness). Against a gray background, the green spill is evident around the hairline. If we were to attempt removing this by erasing pixels (magic wand, magic eraser, etc.) then we would also erase the hair. By using the color range selection or the background eraser, the hair detail is left. The hair is semi transparent where it needs to be. The only issue is the green hue left in the hair.

The first step to correcting the green spill is to lock the transparency in the foreground layer. You simply click the button shown in the image to do that. This will preserve the transparency values of all pixels in this layer. This will be needed for when we use the brush tool to correct the hair color.

Next, you will need to setup the settings for the brush. First, set the brush to color mode. This will preserve the luminosity of the layer that you are painting on. The hue and saturation is replaced with the foreground selection color.

You will want to use a fairly soft brush. Somewhere around 50% hardness usually works well. The brush size will of course depend on the image size.

For the brush color, set the foreground color to a color value of surrounding hair using the color picker tool. Make sure the color picker is set to 3x3 or 5x5 pixel sampling to avoid sampling just one pixel. Digital cameras are "noisy' so sampling just one pixel may not pick a good color to match with the hair.

Try painting over the hair edges. If the color isn't quite right then undo and select another color. You can also fine tune the brush color. Most often, you can just adjust the saturation of the foreground (brush) color to get it to match better if needed. Also, You may need to change the brush color slightly as you work around the image to match different areas of hair.

This technique is actually very easy to do. After you do this for a few images, you will get the hang of it and it will become very simple to you.

Here are the results of the green spill clean up. This took less than 1 minute to do for this image. All of the detail is left in the hair line and there is no green hue left over. There is no way to get these results with the magic wand!

If you are using the magic wand for image extractions, try this method and you will never use it again for a green screen removal.

You can then easily replace the background with a digital backdrop of your choice. Also, make sure to save a copy the image without flattening the image to keep the transparency. You can either save the top layer only as a .tif or a multiple layer file as a .psd file. This way you can always add another digital background. Do not save as a .jpg file if you want to keep the transparency. Jpeg images do not support transparency.