Easy GreenScreen Plugin for Photoshop

Shooting on Chroma-key or Green Screen backdrops have come a long way with today’s technological advances. The purpose of this article is to explore the advantages of one plugin in particular; the Easy Green Screen 3.0 plugin, available from: http://ezgreenscreen.com/, as Freeware. The plugin is available for all versions of Photoshop, CS or higher, running on Macintosh or Windows.

I teach a very successful Chroma-Key workshop and I’m always amazed to talk with photographers before our first session. Some of the most common misconceptions I hear over and over are: Never shoot a blonde. The plugins are prohibitively expensive and not very effective, especially when hair is involved. Well, that may have been true many years ago, but no longer… In this tutorial I hope to show you how to obtain high quality results consistently.

Lighting is everything in photography. Lighting on a chroma-key backdrop is twice as important and said to be twice as difficult. As long as you pay attention and meter well, you will find lighting for a chroma-key shot is easy and fun. Nothing more difficult than any other multi-light setup. This should be well within the grasps of any serious amateur or beginning professional photographer.

Flat, even light on your backdrop is essential. I use two Alien Bees 1600’s to light my backdrop. In the past I have attached barndoors and I have had softboxes mounted to my Bees. I believe softboxes did spread the light more effectively at close distances – in confined spaces. However the barndoors makes it easier to move around the studio, so I probably will continue using barndoors when shooting at home. This is not a contest to see who can use fewest lights. If you need to place more strobes on your backdrop, then do so!!


Setting up the studio.

This is the most difficult situation I could dream up; We are shooting in my living room to prove this can be achieved quite nicely in small spaces. The overall room is 9′ x 12′ with ceilings at 7’10”. My backdrop is 12′ long, its 7′ up and 5′ out. I have laid a 4′ wide piece of bright green felt across the front to give my model and myself a little extra safety margin. Kelly is blonde today, so we can dispel the rumors regarding the adverse effects of shooting blondes on chroma-keys.

The first thing I need to do is balance my backdrop strobes. I want the lighting as flat and as even as I can possibly make it. With my flash meter on the backdrop I am aiming towards a reading of f-11. I will walk back to where I intend to shoot Kelly from and make a few test shots to check for dark/bright spots. I can not stress enough flat and even lighting on the backdrop…

The key points is the light on the backdrop with respect to the position of the model, or the light at the model. If I were shooting my model and my main strobe is setup at f-8, I will want the backdrop to reflect back at f-8 while holding my flash meter beside her head. If the backdrop is one full stop under, heavy shadowing will probably occur and you will be left with a mess to clean up by hand. If you are one half stop or more over exposed on the backdrop, you run the risk of tinting the hair or lightly color clothing. I hope you are seeing the key issue here? You’re balancing four strobes, not just the two on your subject. For those of us used to working with complex lighting scenarios, this becomes more of a procedural task. For someone new to studio lighting, this is a great exorcize to stretch your knowledge and skill set.

I love using Glamour lighting on Kelly, but before we go look up lighting patterns, let’s think a minute about the big picture. What we really need to do is mimic the lighting for the scene that we will eventually paste her into. Take a good look at your digital scene, so that we can attempt to match the angles and position of our strobes, to match the sun, etc. I put my stripbox on the floor, angled upwards, this will be my fill. I put my Beauty Dish about 2′ above her angled downwards, this will mimic the sun – my main. I decided to use a second fill, a stripbox behind her to take a bit of the edge off and avoid the harsh dark void on her back.
OK, I made the shot and now we are finished, ready to move on to post processing 🙂


Working in Photoshop.

Assuming you have installed the Easy Green Screen plugin, as per manufactures instructions and you have an image open, we are ready to go. To launch the Easy Green Screen Plugin, go to File > Scripts > Easy Green Screen, after it initializes you will be presented with this option screen. I always select: Preserve Max Hair Detail and Yes to edge shadowing. I move the edge shadowing slider to about the center. These are both settings you are going to need to play with in the beginning. Its all relative to your lighting, your model and his/her clothing, your particular computer and it’s operating system may also have some effect. After processing the same image four or five time, I decided these settings worked best for me – on my laptop running Win7/CS5. It is slightly different on my workstation running WinXP/CS4. Play with it yourself, you will find the best setting very quickly!!

HINT: If you are see to much background garbage, perhaps less Edge Shadowing, or a level less then Max, on Preserve Detail for Dark Hair. I like a little shadow myself. With Edge Shadowing, set to No, I did not have any and was forced to draw in some shadowing later in Photoshop… If you have managed to compose an image not requiring a full body shot, shadows will not be as much of a concern. If your subject is standing/sitting in a scene you may need some shadowing. Your digital scene will dictate shadow requirements.

There are several points I want you to notice here:
First: you will notice the plugin duped your original and produced a copy of it. (I love this)
Second: look at the layer pallet and you will see the finished image generated several masked layers.
Finally: lets look closely at the image itself for issues.

Starting with my second point: I do not want to adversely effect the plugin’s output set, because it is so clean. I will need to tweak several areas within the image in different ways. I prefer to work on a dupe of the set and I might as well work with one layer. So I will merge the three masked layers into one new layer, while preserving the originals set. To do this:
A.) Select the three masked layers.
B.) While holding down the the Alt key, click on the little down arrow at the top of your layer pallet to open up the layer properties sub menu.
C.) Next click Merge Layers. Don’t let go of the Alt key before completing this step or you will merge the original layers into one
Finally; I like to create a group folder and move the originals into it, then turn off the eye ball on the folder, so that i am only looking at the new copy of the merged layer. Before I make any alterations to my new layer, I will link my new layer with the group (GreenScreen). By doing this my new working copy will always retain the same physical aspects and geometric coordinates. Should I need to go back for any reason, the time required will be minimal and the accuracy will be dead on.. Highlight the new layer + the new folder> Right click> Link Layers.


Fine Tuning the Image.

Now we can carefully fine tune our image. I do have a slight green cast reflecting back into Kelly’s blonde hair. I will need to go around the edges and make a color adjustments to 4 or 5 small spots. There are several ways to do this. You can use the lasso tool, I like to make them all at one time, so I will use Quick Masks, then Select/Inverse.
After resolving the green cast in the hair, I will go ahead and touch-up the image as I would normally; adjust the curves, brightness & contrast, color, skin touch-ups as needed, etc. Whatever is the norm for you and your style.
I also noticed a heavy shadow along the bottom of the image. This ‘shadow’ is actually the piece of green felt I laid down under the leading edge of my Chroma-Key backdrop.. I will erase this very carefully before proceeding.

The Final Step.

Finally we are ready to add our digital background. With the layer Add Backdrop selected, paste in your background. If you are lucky, you are finished. I was not so fortunate and will require several adjustments in order to make the image ‘believable’. I see a gray cast or her leg and calf that needs some color. The back lighting I added at the last minute was to high and now I will need to adjust the image in Photoshop.

To make these corrections I will use masked Adjustment layers. To do this:
1.) Highlight the ‘Kelly’ layer in your layer pallet.
2.) Click the little half darkened circle at the bottom, center of my layer pallet.
3.) When presented with the option menu, I selected Curves. I made the adjustment I felt the image needed. The adjustment layer altered the entire image. I only want to shad and darken the back of her head and shoulder.
4.) To hide this effects from the entire image, hold down your Ctrl Key and press I at the same time. This will Invert your mask and Hide All, effects.
5.) Now click in the center of the Curves adjustment Mask. Notice the little frame around the black mask? You have selected the mask.
6.) Now using the white paint brush set at about 20% flow rate, paint the areas that needs to be darkened. To see/hide the effects of this mask, click on the adjacent eye ball on the left side, layer pallet. The effects of your adjustment layer should become obvious.

The beauty of using Masked Adjustment Layers, is that if you go to far, just change to the Black paint brush to add the masking effect back. White – Reveal All Masks, are exactly the reverse. Black paint hides all, white paint shows all. For even more control you can adjust the Flow or Opacity sliders of the layer.

In retrospect I didn’t need the second fill behind my model. I could have saved myself some valuable time, but then you would not have seen my simple method of dealing with it. I’m still pleased with the image and the total time required was about 10 minutes. Granted Kelly has a perfect figure and a perfect complexion. Working with a Pro model who only gives you flattering poses really helps. (my little disclaimer; Your time may very).

Other Thoughts and Considerations.

The Easy Green Screen, Plugin itself.
In my humble opinion, this plugin is far superior to most all commercial plugins available on the market today. With the only exception being; it only works with Green, Chroma-Key backdrops at this time. I understand Green/Blue Chroma-Key backgrounds are currently under development 🙂 This plugin is Freeware, but I would strongly encourage you to make a donation to the plugin developer. This will help to ensure it’s worth Damon Bell, time to continue development on this Outstanding Plugin!!

Hair and Clothing Color.
Blondes and Platinum Blondes are the most difficult situations you will have to deal with. Green eyes and clothing can cause issues, but its easy enough to go back to the Mask Layer and unmask any areas the plugin removes during the process. Simply click on the Black – Hide All mask, and using a white paint brush, paint it back in… 🙂

The Digital Backgrounds.
There are a zillion considerations you should be aware of when selecting a digital background images. We are only going to discuses a few here, you’ll get the hang of it as you go along. I hope to have a DVD available shortly of my Chroma-Key workshop, where we cover so much more then here.

Where to get the backgrounds; Well, shooting them yourself is a great excuse to get out and enjoy photography! E-Bay has several commercial suppliers, but just like anything from e-Bay you need to be careful what you are buying! Make sure you are purchasing backgrounds with the same or greater resolution then your base – Chroma-Key image.

Licensing Agreements on Digital Background images are another thing you need to pay attention too! Usually – the best, allow full commercial and privet usage rights once you apply your new top image. Not all licensing agreements are the same, know what you are buying! I would not recommend taking images off the Internet for several reasons. First the resolution is to low, we only want High Resolutions images for our purposes. Next it’s my understanding the photographer always retains the copyright (in America) until s/he sells or leases the image rights to you. For additional details on this, consult a competent Copyright Attorney in your area.

Selecting the proper background image is an art form in itself!! All of the tutorials I have read usually suggest you compose your image so that the feet are not in the final image. This certainly helps and may be something you would wish to follow in the beginning..

Well, on behalf of Kelly and myself I hope you have as much fun playing with this as we did shooting it!!

Ciao
~Dave


 


Recently Damon Bell, the Easy Green Screen Plugin developer dropped by to explain a few of the differences and to inform us all of the latest versions and features…

Thanks so much Damon, that really helps!!
Dave

by Damon

Hey Dave,

First, great article on using Easy Green Screen. Thanks for posting it.
I just ran across this so I thought I’d reply to answer a few questions that people have (I am the developer of Easy Green Screen).

1. Yes, you may put a link for people to download EGS 2.2. That is perfectly fine. I removed the link from my website so I didn’t need to support 2 versions.
2. The reason for the changes to the extraction algorithm in version 3 are two fold.
First, EGS 2.2 did not do well for loose strands of hair. it would generally mask them out. The new method in version 3.3 / 3.4 works much better for getting hair detail, although it requires the user to tweak 3 different levels adjustments.
Second, if there were two different sources of green for the background, V 2.2 may not extract it well. EGS 2.2 extracts almost exclusively based on hue. This allows for it to be very aggressive to extract shadowed areas because the hue doesn’t change much between the lit and shadowed areas of the screen. However, if the hue varies in the background by more than 7 or 8 degrees, some areas won’t be extracted well. This become a problem in cases where multiple background sources are used.

For example, if a separate green floor was used together with a green chroma key backdrop. If the hue of the floor was not exactly the same as the backdrop then there can be extraction problems. EGS 2.2 will analyze the image and average the hues between the 2 background sources which becomes the target hue for extraction. So for example, if the BG hue is 120 and the floor hue is 140, then the target extraction hue would be 130 (assuming the floor and BG are equal sized areas). For this example, neither the floor or the BG would extract well. This problem was reported by several users who do full body shots and use a separate green floor together with a muslin backdrop.

3. EGS 4 is in development. The plan for the new version is to give the user a choice between the 2 different extraction algorithms. I don’t have an ETA for V 4 yet. It will be at least 3 or 4 months though.

Damon Bell
http://ezgreenscreen.com/