Green screen background removal

[artur]

Hey all,

Here is a tutorial I wrote about removing green screen from your image in order to apply a digital backdrop. This tutorial is done in Photoshop CS2 and is copied from my Chroma Key Information Site (CKIS): Green Screen (Chroma Key) Information Site

Easy removal of background in Photoshop
By Artur Gajewski

The most fascinating thing about Photoshop is that there are always many ways of doing certain thing. You can choose how you make something your way.

One of teh hardest thing I have come across in Photoshop during the time I have used it is to seperate model from the background. The thing that makes it so hard is to successfuly masking the hair. I have spent many weeks reading tens of tutorials, websites and books on how to do this.

None of the method I have come across satisfied me, because either they consume way too much time per image or the outcome was not satifactory in my eyes.

There were many articles that mentioned not to use the background eraser tool, but what I have discovered is that the background eraser tool is exactly what makes the background removal easy, fast and so that even with difficult hair the outcome is very nice.

On this tutorial I worked on the image generated by 8 megapixel sensor, meaning dimension of 3456 x 2304 pixels. Please note that all the settings in this tutorial are based for this image size. If you have different image size the settings won't necessarily work for you.

Without further talks, lets get into business and do the background removal in just 16 steps and about five to ten minutes. You can click on the image of each step to open up larger version in a different window.

STEP #1

Open your image with the model and also the digital background image. Make sure the background image has same dimensions as the image you will work on. Copy the background layer to the green-screen image into a layer of its own. Make a duplicate of the green-screen layer with the model into a seperate layer. We will use this layer to remove the green background and from which we will later make a selection mask onto the background layer. You can now hide/un-activate the original layer that you just made a copy of.

As you can see the background is not evenly lit and it contains wrinkles and shadows. This is just fine, you DON'T need to spend all your saving purchasing expensive Chromakey backgrounds and try to figure out how to correctly light them. Just remember to use such color in the background that is not used in the model's face or clothing.



STEP #2

Next, select the Background Eraser - tool from the tool palette. Set the brush's radious so that it fills 1/3 of the image heigth and tolerance to about 20%. Mode should be set to Discontiguous, because we want to remove the green color everywhere it shows up, even in between the hairs.



STEP #3

Notice that the area that this tool will erase the background is inside the brush outer circle, while the crosshair in the middle of it is the point from you need to sample the removed color.
From the bottom left, start clicking about 30 pixels from the model so that the crosshair is always on the green background. Make sure you do not put the crosshair on the color of hair, clothing or skin as this will sample the wrong color and remove the person itself instead of the background.

Take notice of the tolerance setting. If the background won't remove well, increase it. If the tolerance setting removes parts of person, go back a step or two, reduce the value of tolerance about 5% and try again. Once you know how to handle this, the removal process is easy.

Don't worry if there are some green around or inside the hair sections, we will easily fix this later on this tutorial.



STEP #4

When you have removed the green area around your model, now you can remove the green area from the outline of the model. Choose normal eraser tool and remove the leftover green from the layer.



STEP #5

Now we are going to make a selection mask. You now should have three layers: Original image on the lowest layer, background image on the middle layer and the foreground layer on the top layer that we just worked on. Activate the layer that we removed the green background from, hold down the Control key and click on the layer icon. Now you should have a selection of the foreground as in the image on the right.



STEP #6

While keeping the selection, activate the background layer and click on the "Create selection mask" button to create a selection mask. Hide the layer that we removed the green background from and now the background appears to the back of your foreground model. Easy, isn't it?



STEP #7

Now to make the edges soft by using the mask, we need to blur out the mask. Not much, but enough to make the edges of your foreground smooth.

Click on the background layer's mask and go to Filter -> Blur -> Gaussian Blur and apply radius of about 0,9. This settings works fine for me, but you might want to experiment a little.



STEP #8

Now we have a nice extraction from background already, but as you can see there are still some greens in the hair.

This is called "Green spill" which comes from the model being to close to the background and green color has been reflected to hair. Same can happen to clothes and other objects.



STEP #9

What we need to do is change the hue of the green areas. Activate the original layer at the very bottom. Zoom in the image very close into the hair that contains the green spill.

On the activated layer, create an adjustment layer for Hue & Saturation.

From the Edit menu select "Greens" and choose the color selection pippet. With the pippet, click on the part of the hair that has the green spill.



STEP #10

You might want to adjust the color range to work on. For this particular image, I have set the following settings that produced satisfactory:

HUE: -34
SATURATION: 0
LIGHTNESS: 0

Ofcourse you need to find the perfect hue, saturation and lightness levels to mach your model's hair color.



STEP #11

Because we changed the hue of the remaining green screen area around the hair, we also changed the greens around the socks.

Now we need to fix the green border around the socks by doing another Hue & Saturation modification.



STEP #12

First select the Lasso tool which we are going to select the area where we now have yellow border around the socks.



STEP #13

Make sure that bottom layer that is below the background layer is active. With the Lasso tool, select the area you need to fix. Here I selected the feet area along with the socks, because as you can see it contains yellow outline that used to be green.

While keeping the selection active, zoom in into the part that has the yellow outline and create an adjustment layer for Hue & Saturation as we did previously on step #9.



STEP #14

From the EDIT menu select this time Yellows. With the color selection pippet, select an area that has yellow outline around the socks. You might want to adjust the color range to work on.



STEP #15

For this particular image, I set the following values that removed the yellow outline from the pants and socks:

HUE: 0
SATURATION: -88
LIGHTNESS: +55



STEP #16

And here is the final outcome! As you can see, things can be done the easy way. Instead of going the hard way and doing complex masking solutions that consume time and requires skills, we have done the same in 16 steps and about 10 minutes or so.

Please not that this tutorial is not the die-hard only-way of doing this kind of work. You can elaborate on these steps if you want.

The idea of this tutorial was to show you the basic steps on how you can accomplish complex background extraction with minimal efforts.

If you like this tutorial, have any comments or want to send me a picture of background extraction using this method, send me an email to artur.gajewski @ majgaj.com.

[felix.reichardt]

Great stuff! Do you you one of these special green backgrounds for this or will any green do the trick?

[Tusker]

Originally Posted by artur

Hey all,

Here is a tutorial I wrote about removing green screen from your image in order to apply a digital backdrop. This tutorial is done in Photoshop CS2.

Easy background removal in Photoshop

ART- THANKS!! Now an easy way to remove those pesky phone wires when they cannot be avoided In PS C2??

[artur]

Originally Posted by felix.reichardt

Great stuff! Do you you one of these special green backgrounds for this or will any green do the trick?

Basically a green with anough saturation or green level will do and the one that is not used on the subject. I would go for a neon green if possible. As you can see from this tutorial, even lighting is not required.

Here is another example, don't mind the crop...

[jfrancho]

nice one. I added it to the list: http://photocamel.com/forum/image-ed...ial-sites.html

[artur]

Originally Posted by jfrancho

nice one. I added it to the list: http://photocamel.com/forum/image-ed...ial-sites.html

Thanks

[Worm324]

Awesome tutorial!! Thanks for sharing This looks much easier than the method I'm using. I had no idea there was a background eraser tool

Best,
Jay

[Worm324]

WOW, I just tried it and it works incredible good!! It took me about 5 minutes instead of 15-20 minutes!!

Thanks again!

Jay

[artur]

Originally Posted by Worm324

WOW, I just tried it and it works incredible good!! It took me about 5 minutes instead of 15-20 minutes!!

Thanks again!

Jay

You're very welcome Show us the results!

[Worm324]

Here is the 1 I just did last night for a test of this new method. This took a total of 10 minutes start to finish!! I didn't do any touch-ups on me so it could use another 10 minutes of polishing, but as far as the extraction goes:


Thanks again,
Jay

[jfrancho]

Nice job Jay! I took the liberty of touching it up, hope you don't mind...



A little better?

[Worm324]

lol WOW your incredible at PS man!! I should though that up on my website, the chicks would dig it!!

[RockyPtJoe]

Originally Posted by jfrancho

Nice job Jay! I took the liberty of touching it up, hope you don't mind...



A little better?

Fantastic use of the liquify filter!!!!

[Worm324]

I like how he added the "just drank about 10 cocktails" look as well