Seperate objects from green backdrops with presicion and control. Learn how to mask fine strands of hair and a translucent glass cup.
Identify the Green Backdrop
Before we add layer mask, we need to identify the green areas and create an black and white layer to represent the transparency of the image.
Step 1
Open a photo you would like to edit. Or, you may use the photo used in this tutorial . Make sure that the image is in RGB color mode. To switch to RGB color mode, click on RGB Color under the Image> Mode menu.
Backdrops Green Keying
Step 2
Add a Channel Mixer adjustment layer (Layer> New Adjustment Layer> Channel Mixer). In the Channel Mixer window, check the Monochrome checkbox and set the Red to 200% and the Green to -200%. Don’t close the Channel Mixer window yet!
Backdrops Green Keying
Step 3
Now drag the Constant slider towards the right until the object is a 100% white; not gray. Don’t go overboard with the constant setting. If the constant is set too high, the images’ edge detail will be loss.
Backdrops Green Keying
Step 4
You’ll notice that after apply the Channel Mixer adjustment layer, the green areas are not completely black. If we leave this alone, the greens will only be 50% transparent instead of 100% transparent. To fix this, select the Background layer and open the Hue/Saturation tool (Image> Adjustments> Hue/Saturation or Ctrl+U). In the Hue/Saturation tool, select Green from the Edit drop down menu and increase the saturation until the green areas turn black.
Backdrops Green Keying
Convert Layer to Mask
Step 5
Before we can add a layer mask to the Background layer, we need to unlock it. To do this, simply double-click on the layer and a New Layer window should appear. The default settings are fine. Click OK.
Backdrops Green Keying
Step 6
Add a layer mask to the layer we have just unlocked (Layer> Add Layer Mask> Reveal All).
Backdrops Green Keying
Step 7
Make sure the layer mask is activated. The thumbnail of the layer mask in the layers window should have a white border around it. If it doesn’t, click on the thumbnail to activate the layer mask.