Below is an image I took on a green screen.  One of the issues with using a green screen is the green cast that is thrown on the subject.  Notice the spill of green on her face, neck, left arm and especially her leg and shoe.  There are other software products that help reduce this, but if you don't have access to those you need to know how to accomplish it in Photoshop.  As with anything in Photoshop, there are many approaches to how to resolve this, even within the same tool.

 

 

My Photoshop approach is as follows.  Select the Hue and Saturation Adjustment.  You can do this in a couple of ways.  I have the Adjustment Layers panel available so I usually select it from there, but you can also select it by opening the Layers menu and selecting it from the Adjustment Layers option.  When the Hue and Saturation dialog box opens be sure to select the appropriate color channel.  In my case, the above image has a green cast so I select the Green channel.  Next, notice there are some Eye Droppers about 2/3 way down.  Select the dropper with the "+" next to it.  Now, go to your image and take a representative sample from your image.  In our case this is the Green color cast and represents a selection of the color you want to remove.  Once you have made this selection, return to the Eye Droppers and select the dropper with the "-" next to it.  Now, you want to go to your image and select a sample of the color you want to replace the color cast with.  This narrows the color being affected and the replacement color that will be used.  After selecting the samples you need to tell the adjustment tool how you want to make the adjustment.   Go to the Hue slider and slowly move it one way or the other.  You'll see the color begin to change.  If you move it the wrong way the wrong color (green in our case) will intensify.  Just move it the other way and notice it begin to improve.  Slowly adjust it until you have it the way you want it.  You may have to do this several times because you may have differing intensities of the cast (some may be darker as it goes into shadow).

 

Hue and Saturation Adjustment Panel

You're not done yet.  This adjustment has affected the entire image, but you only want the specific areas corrected.  Adjustment layers are layer masks by definition.  Therefore, you can paint the adjustment where you want it.  Fill the adjustment layer with Black to conceal the adjustment.  Do this by clicking on the mask in the adjustment layer and then selecting CMD-I to invert the fill selection.  Now your adjustment is hidden (the mask is filled with Black) and you see your original image.  Press B to select the Brush tool and change the opacity to about 20%.  Change your foreground color to White and be sure the Brush is the right size and fairly soft.  Slowly begin to paint your adjustment into the area you want to change until your get the effect you want.  Remember that you can also change the density and feather properties of the adjustment if you need to for a better effect.  Here is my image cut out and before and after using this technique.

 

The cut out image before and after the hue and saturation adjustment

Before the Hue and Saturation Adjustment

After the Hue and Saturation Adjustment

 

In some cases this may not be the best tool for fixing this problem, but it's pretty easy to do and is another tool in the toolbox.  Let  me know what you think.

 

Hope this was helpful.  Happy shooting.