Three Chroma Key Solutions For The DIY Photographer
The following post about 3 ways to DIY your Chroma Key was made by Ben Eadie of DVRebelGear.com.
There are several ways to get a decent chroma background for a photo for the DIYer and the results are just as good as any pro system I have encountered. We will cover 3 solutions I have used with great success and all cost less than $15. You can use a green sheet, you can paint a wall and you can make a pop out chroma key like a pop out reflector. I use green for my key but you can also use blue if you choose.
First here is some advice on getting a good shot on a chroma key. Never use an on camera flash. Make sure your object is far enough from the screen to not pick up any green reflection off of the fabric. Your object/subject should not cast a shadow on the key. Avoid shiny things (note the top of the table in the examples below, they all have a green reflection in them because it is a slightly shiny surface) I make sure that I have things a minimum of 3 feet in front of the key. Last make sure you have an EVEN soft light on the chroma color. The more even the light on the key the easier it is to edit later on in your photo editor.
First, the green sheet. You can get fabric sheets at your local WalMart. Get a green that looks close to the green in the pictures below. Or you can even get the fabric off of internet stores such as http://www.joann.com (get the Symphony Broadcloth in green here) Now this is as simple as hanging it on a wall with tacks.
Advantages: Super simple, easy to move and store, can be draped over things to key out later, cheap and easy to replace
Disadvantages: Wrinkles easy, sometimes hard to hang
Second, if you have a wall available to paint then go to your local paint store and get some flat latex paint. The cheap stuff is fine and here is the color code you will need to give them to get the right tint of green (note this is for a small 872ml or 29.5 fl.oz container) B-1 KX-11 AX-1Y31.5 D-1Y4
Advantages: Once a wall is painted there is no setup, smooth even surface
Disadvantages: Not portable, you have to have a wall to paint.
Last is to make a portable pop out chroma key much like a pop out reflector. Now these normally cost a fair amount of money to purchase but you can make one for really cheap by following the instructable I made a few months back. http://www.instructables.com/id/Pop-out-photography-reflector-or-chroma-key/
Advantages: Portable, less prone to wrinkles, looks pro, easy to hang or prop up
Disadvantages: Size limitations, sometimes wrinkles
Now this was short and sweet but really all you need to do is get yourself one or more of the options above and start experimenting. Have fun!
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Comments
why green and not... white?
Hello, sorry to disturb... just wondering... why should green be used?
considering that i have to go into photoshop, why not use a white background/wall?
isn't it the same as a green wall? once it's uniform color, it takes nothing with photoshop.
where am i wrong?
re: why green and not... white?
With a photo and photoshop, it's true you could use white or some other solid color because you have more control of the selection process.
The main idea behind chroma key is that it's an automatic process, especially when used with video. The reason green and blues are often used is because skin tones don't contain these colors, where using white for example would also remove eyes, teeth, clothing, etc. if done by automatic process. Needless to say, you have to make sure your subject isn't wearing green/blue.
Since this object didn't have
Since this object didn't have any white that would interfere with removing the background you could probably get away with shooting it on white. It would also remove the green color cast in the reflection on the wood table.
Red, green and blue channels
Red, green and blue channels have all been used, but blue has been favored for several reasons. Blue is the complementary color to flesh tone--since the most common color in most scenes is flesh tone, the opposite color is the logical choice to avoid conflicts. Historically, cameras and film have been most sensitive to blue light, although this is less true today.
Green has its own advantages, beyond the obvious one of greater flexibility in matting with blue foreground objects. Green paint has greater reflectance than blue paint, which can make matting easier. Also, video cameras are usually most sensitive in the green channel, and often have the least noise in that channel. A disadvantage is that green spill is almost always objectionable and obvious even in small amounts, while blue can sometimes slip by unnoticed.
Sometimes (usually) the background color reflects onto the foreground talent creating a slight blue tinge around the edges. This is known as blue spill. It doesn't look nearly as bad as green spill, which one would get from green.
Green cast?
I agree Gabriele.. why not use white? That way you can avoid the green color cast as well.
Gabriel is exactly right.
Gabriel is exactly right. Green/blue chroma key is made for video/motion and is specifically designed to be at the opposite end of the spectrum against skintones. Anything for still images should be done with a neautral background like white, black or grey (depending on the subject). Notice how much green cast is contaminating the image even though the green has been 'keyed' out? The wood pedestal is green and practically uncorrectable. If you are a beginner looking to learn about this, ignore the above tip and Google "photo masking" instead.
I'm upset that some one would
I'm upset that some one would chroma-key something, contaminate the wood with color cast, and put a white background in, when the most logical choice would be to shoot it, on a white backdrop that is correctly lit..
Green VS white background
Jake and all
The green background on this photo was ONLY to show the different ways to use chroma it was not a logic decision. If I was to make the photo like this I would have used a white backdrop. I should have inserted a background graphic to show the real reason why one would do this. I apologize for that. If I have some time this weekend I will add a background to the photo. The reason I used white was to show how clean the edge can be using this method.
Best
Ben
Better use of the chroma
As I stated in the last comment white was used to show how clean an edge you could get with this method. Here is a better concept of what can be done with this much easier than if I had used a white or black bacground. Also consider I am a video guy and green makes more sence as I can batch edit the frames vs doing them each by hand.
Cheese and Rice!
It even spells it out in the article. "Avoid shiny things (note the top of the table in the examples below, they all have a green reflection in them because it is a slightly shiny surface)..." (emphasis mine) It was done intentionally to show why you shouldn't do that. Don't use a shiny surface because the background will reflect off it.
Ideally, pick a color that isn't in your subject. If you can, pick chroma-green or chroma-blue because there's software out there that can take them out automatically. If you have a subject that will reflect the chroma color, pick something else.
Green
I think it's funny that they would say "Make sure your object is far enough from the screen to not pick up any green reflection off of the fabric" and then show photos with a TON of green reflected on the podium the frog is on. Was that intentional? You know, green goes with frog sort of thing?
ok i'm in with the white
how ever.....
i do video too and the green cast drives me nutz when ever i see it. it is simple to fix. if you want to shoot with green back drop, Rosco and Lee both make a gel color that is the contrasting color to the green, use this over a back light. and you will get a normal white. how ever if you are going to go to all that trouble just light a whit back drop. less trouble.
the lee number are 248, 249, 279 i dont know roscos.
Filters
John
COOL!!!! thanks for the tip I will be ordering gels first thing to try them out. Thanks for the tip!
Ben
Proper Lighting
The color cast will not be a problem if you light your subject properly and you using proper spacing from the wall. Using the bright green or blue is the most versatile in my opinion for shooting a variety of things and is the easiest to separate. Like I said if you don't take the time to light something well after you put all the work into making the background it's pointless.
Proper lighting
Very true on the lighting. I had a head slapping moment the other day. I have a white ceiling in my studio and I pointed a 250W bulb at it and found that it lit the chroma key nearly perfectly and evenly and also cast a great overhead light on the subject with nearly no color cast. With one light! Then what I did was made a 30"x20" silver reflector and tacked it on the ceiling right over the subject and pointed slightly away from the chroma wall and it reflected a much better outline and got rid of the green entirely
Never thought to use the ceiling as a bounce board and thus the head slapping moment
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