Chroma keying, otherwise known as shooting with a green screen, gives product photographers a lot of creative freedom without the need to leave the studio. It’s a low-budget tool that can place a product in front of virtually any background you want.
Follow these steps to shoot a chroma key product photo:
- Choose a background image for the composition
- Place the product in front of a green backdrop
- Shoot the photo, consider the background image while composing
- Load the background and foreground images into a post-processor and set the chroma key color
Turn Your Product Photos Into Infographics Without Hiring A Designer
Chroma keying is a handy tool in photography and videography, and the product photography industry is no exception. Clients sometimes want more than just the standard “white background” product photo; so read on to see how to deliver more by using a chroma key.
What Is Chroma Key Photography?
Many of us are familiar with the other term for chroma key: green screen photography.
Chroma key photography is the art of shooting a subject in front of a solid, colored backdrop and replacing that color with any image or gradient to produce the illusion of a different background.
It is a digital effect that “keys out” a range of hues or chroma range. More commonly used in video production due to its ability to quickly “mask” a layer, it does come in handy for quickly post-processing still images.
This technique works by making a range of hues transparent so that the photo’s subject can be placed in front of the desired background image. Using a solid color for the backdrop keeps this range narrow and decreases the likelihood of any part of the subject being made transparent as well. The result is a composite image with two layers, a foreground and a background.
Can’t I Just Use A Layer Mask?
You may be thinking, “I already know how to mask layers in Photoshop; what the heck do I need a green sheet for?” And if you don’t already have a basic understanding of composite images and layering, it would help to get familiar with it.
The benefit of chroma keying is speed and efficiency in post.
As we’ve just mentioned, it’s why green screens are so common in video production. There is no need for someone to go frame-by-frame, selecting the subject with the magic wand tool and masking it out. No, the post software automatically masks anything green.
Granted, while a product photographer will only be dealing with one frame, it is still a pain to manually crop out a subject. Especially if there is poor contrast between the subject and the background.
In photoshop, a chroma keyed background can be selected all at once with the magic wand tool for quick masking.
Also, there are several other, less expensive chroma key software applications available specifically for chroma key photography, FXHOME PhotoKey or Photoshop being more popular options. The other chroma key software are:
- Green Screen Wizard
So if you’re a product photographer on a budget, here’s a way to add flare to your work without spending the big bucks.
In short, chroma key photography places a subject in front of any background without it actually being there. A pretty handy tool for product photographers who work mostly out of a studio.
How Is A Green Screen Useful For Product Photography?
Chroma key is a very versatile tool that can come in handy for product photographers. As we’ve hammered home, it provides the ability to virtually place a subject in any setting. This provides a lot of creative freedom to add information to images that will almost always be used for advertising.
Some of the possible options include:
- Place product in a unique setting
- Include informational text or other ad copy
- Include colors and graphics that align with the client’s branding
- Place product in front of a pure white background
Place The Subject In Any Setting
It’s common to incorporate lifestyle photography into product photography.
Clients may want images of the products being “used in the field” because it increases the desirability and conversion of the product. While the best option here is to shoot on site with models, a chroma key makes this possible within a studio for smaller budgets.
The background can typically be any stock image, and it could be used to place the product in a more appropriate context which will be cheaper than hiring models or going to a specific location. Especially if a client is looking for more than just a white background.
It’s very important to consider subject lighting when doing this!
You’ll want to use lighting filters and adjust the lighting direction to match the perceived light source in the background image. The benefits of the chroma keyed background can quickly be spoiled if the subject lighting does not match the virtual setting.
Include Additional Client Info
If the product photo in question will be used for an ad, then a chroma key can be used to place the product alongside ad copy or in front of client branding. Basically, once you mask out the keyed hue, any digital background can be incorporated. And the ability to do so quickly is what makes chroma keying so useful.
Chroma Keys Can Still Be Used For White Backgrounds
If you only have enough room in the studio to choose between a white backdrop or a green screen backdrop, the green screen is the more versatile option without giving up the ability to produce images with white backgrounds.
As long as it’s lit properly, it’s as simple as loading in a pure white image as your background in post. That’s the beauty of a chroma key, literally, any background image is possible.
A Chroma Key Provides Nimble, Creative Freedom
Once the green screen is set up, subjects photographed in front of it can be edited quickly and effectively in post to create an image that’s more interesting than just a product in front of a white background.
While those types of images are usually a product photographer’s bread and butter, they may encounter clients looking for more creative images.
Once you get the hang of chroma keying, you’ll be able to deliver just that.
How Do I Chroma Key An Image?
There are two essential steps in the chroma key process.
- Photograph the subject in front of a green screen
- Key out the green background in post
It’s worth doing your due diligence when setting up the green screen to reap the full benefit of the chroma key. When a green screen is properly set up, post processing the image becomes the easy part… and it doesn’t require a Hollywood budget to create a high quality screen.
Set Up A High Quality Green Screen
First thing’s first, get yourself a green sheet to use as a backdrop. These are not difficult to come by; check out a local fabric store or just order a purpose made green screen fabric online. They aren’t too expensive, and you’ll know you’re getting the best color for a chroma key (more on that later).
When setting up the screen, it’s important to come up with a way to stretch it tight to remove wrinkles.
Wrinkles will cast shadows, and shadows will create areas of different hue in your image, thus lowering the quality of your chroma key background. Remember, the goal is to create an even, solid color behind your subject.
Depending on the thickness of the sheet, you may need to back it with something to remove any transparency when lit.
Everybody’s studio space is different, but in general, the best bet is to hang the green screen in front of a wall. If that’s not possible, backing it with some wood or cardboard is a good option. This is not necessary, especially if the screen is lit properly, but it is something to consider if you are having issues with your chroma key down the line.
What Type Of Fabric Is Best For A Green Screen?
Believe it or not, there are a large variety of green screens you can choose from that range from plastic and foam, to paper and fabric – and depending on the project you’re working on you’ll want to use one type over the other.
If you just go out and purchase a green screen, you may end up buying way more than you need or you can get the wrong one and regret it. One of our first backdrops that we purchased was a large fabric backdrop that was way too big for our studio, and it was very cumbersome to use.
In general, you will want to use a fabric green screen if you are working with a large product or need to chroma key a large area. However, they are prone to wrinkles that need to be ironed out. Paper green screens are great for smaller products but are more expensive the larger the size.
Below are a few options you may want to consider if you’re planning on purchasing one:
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Light The Green Screen And Subject Properly
Arguably more important than the screen itself is how it’s lit. Whether your studio is fully professional or you’re on a DIY budget, the key thing to remember here is the need for two separate lighting zones:
- Zone 1: Lighting the green screen
- Zone 2: Lighting the subject
In both cases, the best bet is softening the light with softboxes. Here’s why.
- We’ve mentioned the importance of stretching out the sheet to remove wrinkles. We don’t want shadows creating variation in hue. The same objective needs to be considered when lighting Zone 1.
- The goal is to avoid lighting hotspots or gradients across the green screen. If one area of the screen is more brightly lit, it will appear a different hue to the camera. This will end up distorting the chroma keyed image, especially if using a chroma key specific software.
The most common way to light a screen evenly is to place a light on each side and use a softbox. Make sure that the screen lighting is placed behind the subject, which brings us to lighting Zone 2.
When lighting a subject for photos in front of a green screen, there are a couple of things to consider.
- Distance from the screen
The first thing to understand is the need for physical space to create the two separate lighting zones. If your screen is lit with a pair of studio lamps with softboxes, make sure there is enough room for your subject to be placed in front of the lamps.
The end goal here is to avoid having your subject interfere with the screen lighting in zone 1.
If you’re lighting your green screen and your subject with the same lamps, the subject is bound to cast a shadow on the screen, which will distort your chroma key.
So, placing the subject far enough in front of the screen lighting will help avoid this, but it is not the only thing to consider. As you compose your image, you’ll be setting up lamps to light the subject. Consider a softbox here as well. If the subject light is too intense, it could still cast a shadow on the green screen, which we already know we want to avoid.
So the perfect green screen is set up, and due diligence has been done, now what?
Snap The Photo And Load It Into A Chroma Key Software
With a properly set up green screen, this is the easy (and fun!) part. At the most basic level, a chroma key photograph is a composite photo with two layers:
- A foreground (subject)
- And a background
The photo you shoot in the studio serves as the foreground layer. Selecting the background layer is where the fun part lies. It can literally be any image…
- Stock photos
- Images you’ve shot
- Computer graphics
Anything goes, and it’s usually helpful to have a background image selected before shooting the subject. Or, at the very least, have an idea of which setting you will want to digitally place your subject in.
Knowing the background image ahead of time will help compose the shot of the subject. Consider the scale of the product as it will appear in the setting. You don’t want something small to appear huge when placed in front of the background.
Also take extra care when lighting the subject.
We’ve mentioned how to light the subject and screen separately, so consider lighting angles and colors on the subject that will make it look like it belongs in the background image. If the background image to be used has cold lighting, then use cold colored lighting to light your subject as well.
In order to create a chroma key image, collect a foreground image and a background image.
The most basic chroma key software will have you perform three easy steps:
- Load in the images
- Specify which is the foreground and which is the background
- Identify the color to chroma key
And that’s it!
Using Photoshop for Background
If you’re working with Photoshop, the green backdrop in your foreground image will help you create the desired layer mask. Without getting into a complete photoshop tutorial here, these are the basic steps to key out an entire color in photoshop.
- Create a layer mask
- Select the colored background using the magic wand tool. You may need to adjust the color tolerance
- Fill the selection with the appropriate mask color (usually black) to make it transparent
- Copy in the background image as a separate layer behind the subject image
No matter which software you are using, the concept is the same. Tell the computer which color to make transparent and mask.
Does The Chroma Key Have To be Green?
Technically any color can be used for a chroma key background, however green and blue are typically the best options.
To understand why that is, it helps to have a basic understanding of how digital photography works. When the light from the lens hits your camera’s image sensor, that image sensor breaks it down into thousands of pixels. The color of each pixel is digitally written as a combination of three hues:
But to more broadly answer the question of which color is best for a chroma key, consider this answer:
The best color option for a chroma key is the color that is not included in your subject.
Said again, the best color option for a chroma key is the hue that is least used in the pixel definition of an image. In most cases, this is bright green. Blue is a close second, and red is rarely used since it is common in many products.
What happens if the subject has the same or similar color as the chroma key? They appear invisible. When used intentionally, this can create some cool (and hilarious) effects. But as a product photographer, your clients will probably want their products very visible.
The best bet is to go with a bright green sheet as the background, and maybe keep a blue one as a backup if you need to shoot any green products. Again, the hue level is important to note here as well.
If the hue of green is significantly different from that of the green screen background, then your image will turn out ok. But in most cases, it’s best to use a totally different color.
The Importance Of Lighting And Chroma Key Color
Choosing the color of a screen to be chroma keyed is important.
Green is typically the best option, but the physical pigmentation that colors the screen is not the whole battle. Once the screen is up and lit, pay close attention to your composition and your camera’s white balance.
We say this because it’s not the color of the screen that’s most important.
The most important factor is the color the screen appears to your camera. Lighting has a big effect on this, as does the white balance setting on your camera. For example, if the white balance setting has you shooting a warmer image, the green screen may appear yellower than it is. This will be a more difficult color to chroma key.
Can You Use Green Screen Photography with a Smartphone?
Yes, the principles of green screen photography apply equally to your smartphone as they do to traditional methods. In fact, the process can actually be streamlined for mobile users, with green screen apps eliminating the need to upload images to a computer and purchase chroma key software.
While this will be easier for a lot of users, you will lose a lot of control over the editing process. Some apps you can use for your smartphone (both Android and iOS) include:
- Stop Motion Studio
- Green Screen Wizard Pro
Remember the following takeaways for a great chroma key photo every time:
- Light the green screen and the subject separately
- Take time to set up a high quality green screen
- Choose a chroma key software that works best for you
Once a high quality green screen is set up in your studio, the options you’ll have in post will be nearly unlimited.