Color cast happens when colored light tints all or part of a photograph. This tint alters the natural tones in the image, making it look unusual or unrealistic. Color casts are a common issue in photography; they’re usually undesirable, though they can also be used for artistic effect.
What Causes Color Cast?
Color cast usually happens when there’s a colored tint in your light source or the reflected ambient light.
Light Sources
Many lighting sources have a distinct color. Incandescent light bulbs have a warm, reddish hue; tungsten lights give off a yellow tone. In most cases, these colors are so subtle that you can’t see them in person. However, since cameras are exceptionally sensitive, they pick up the color of the light. If the camera settings aren’t adjusted to compensate for this color, it can create an unwanted tint on your images.
Some light sources have a more obvious color: Christmas lights and stop lights, for example. These colors are more visible at night and when your subject is close to the source. If you photograph a person next to a neon sign, the photo is likely to have a distinct color cast.
In some cases, mixed light sources can also create color casts; the competing colors of the lights leave an unpleasant tint on the image.
Reflected Light
Have you ever looked in a mirror in a room with colorful walls? Turn on the light, and your skin will take on some of the wall color. That’s because in any given setting, light bounces off different objects and reflects onto your subject – in other words, it creates a color cast.
The same thing happens when you take photos. Take a picture of someone in a neon-green shirt, and you’ll find that the person’s face has a green tint. If you photograph the person next to a red car, their skin and clothing might look slightly pink.
Color casts are more pronounced when the colorful object is large, bright, or in close proximity to the subject. In the woods on a sunny summer day, your photos will likely have a green cast. On a dark, stormy day, your city-skyline photo is likely to look blue.
How Do You Prevent Color Cast in Photography?
In some cases, you can prevent color cast before you take the photo. This is usually easiest in a studio setting, where you have control over the environment and the lighting.
- Shoot on a white or black background –Â This strategy removes color from the environment, so the light can’t reflect color onto your subject.
- Use natural, indirect light –Â Natural light tends to have a more neutral color than artificial lighting. If you can find a white or neutral-colored setting with lots of indirect sunlight, you can avoid most color-cast issues.
- Eliminate colorful objects –Â Remove large, brightly colored items from your scene. Don’t forget about objects that are out of frame – the reflected light can still create a color cast. If you can’t move the object, consider covering it with a black or white sheet.
- Place colored gels on the lights –Â Gels are thin, transparent sheets of colored plastic that sit in front of the light source. They counteract the color of the light itself, neutralizing the cast.
- Use a single light source –Â Multiple light sources often make it challenging to control the look of the final image. Whenever you can, turn off all lights except for your main source.
Prevent Color Cast with In-Camera White Balance Settings
The easiest way to prevent color cast is to adjust the white balance in your camera before you start shooting. White balance is a setting that calibrates the camera to the ambient lighting – that way, white objects look white.
If you’re taking pictures of one subject in a single location, use the Custom White Balance setting. Once you choose your exposure and shutter speed, place a piece of white printer paper in front of the camera. Make sure it takes up a significant portion of the frame, and take a photo. Then, navigate to the Custom White Balance screen, and browse through the camera library to find the picture of the paper.
The camera handles everything else. It recognizes the paper as the baseline for white, and shifts all of the other colors accordingly. If there’s a yellow hue to the light, it will automatically add the opposite color – blue – to the photo. This balances the yellow, so the rest of the colors look normal.
Custom White Balance is helpful if you’re shooting a static scene with consistent lighting. If you’re changing locations frequently, or if your subject is moving, consider using the Auto White Balance (AWB) mode. The camera will measure the light in any scene and adjust the color temperature for you based on the ambient colors.
White balance doesn’t always prevent color cast in your photos. It’s not useful when your scene has:
- Panoramic scale
- Multiple light sources
- Blinking or color-changing lights
- An absence of white or light-gray objects
Imagine that you’re photographing a Christmas tree – the twinkling, multicolored lights send an array of color casts across the picture. Since the scene is changing constantly, the white balance can’t create a consistent calibration.
When your camera’s white balance is ineffective, your only option is to remove the color cast when you edit the photo.
Can Cameras Cause Color Cast?
If you use the wrong settings, your camera can actually create a color cast. This is common in cameras that feature a variety of white balance presets. Each preset is configured for a specific type of lighting. Select a mismatched preset, and the photos will come out with an unnatural tint.
As an example, consider the incandescent white balance preset. It uses blue tones to neutralize the reddish glow from traditional light bulbs. When you activate this preset and take pictures in bright sunlight, the resulting images will have a strong blue cast.
How Do You Remove Color Cast in a Photo?
It’s not always possible to prevent color cast, especially when you’re shooting outdoors or in an uncontrolled environment. Sometimes, you won’t notice the tint until you look at your photos on a large computer screen. Fortunately, it’s a relatively easy problem to correct; most leading photo-editing software programs include multiple tools to solve the problem.
- Color balance: This adjustment features three different color sliders, giving you the ability to adjust the magenta, cyan, and yellow tones in an image. If you notice that your image looks pink, you can reduce the magenta levels; if overcast skies make the entire scene look blue, adjust the blue slider. Color balance settings also enable you to change the settings for the highlights, midtones, and shadows independently. This is helpful when a color cast affects only part of the photo.
- Eyedropper tool: The eyedropper is one of the most overlooked ways to fix color cast. To use it, you’ll need to open the Curves adjustment. Click on the white eyedropper, and click on a white object in your image. The program will adjust the color mix accordingly.
- White balance: Some editing programs, including Adobe Lightroom, have a white balance preset. Open it, choose the automatic settings, and allow the program to adjust the shades. If that doesn’t work, you can use Lightroom’s eyedropper tool to select a white or light gray area to serve as a reference point.
- Temperature and tint: Basic photo-editing programs often feature temperature and tint sliders. To remove a color cast, simply drag the slider in the opposite direction. This counteracts the cast and returns the image to its natural colors. You can use hue sliders to achieve a similar effect.
- Curves and Levels: These advanced adjustment tools give you a high level of control over the colors in a photo. To start, select the RGB space and pick a color channel. Then, drag the line (Curves) or the slider (Levels) to change the temperature of the color. Start with the color channel that matches the color cast, and make small changes until you achieve the desired result.
Counteract Color Cast in a Photo with a Photoshop Filter
Editing functions aren’t the only way to remove color casts; you can also neutralize the tint with a simple filter in Adobe Photoshop.
- Create a duplicate layer of your photo, and drag it on top of the original photo in the Layers window.
- Add the Blur-Average filter to your duplicate layer. The filter looks at all the colors in the image and finds the average tone.
- In the Adjustments menu, choose Invert. When applied, it changes the filtered layer to the exact opposite tone.
- Reduce the opacity of the filtered layer. The original photo will start to show through. Continue adjusting the opacity until the colors of the photo look normal.
This method seems like magic, but the principle is simple. By inverting your filtered layer to the opposite color, you find the perfect shade to counteract the color cast. When you bring down the opacity, the filtered layer sits on top of the color cast, neutralizing its effect.
The inverted Blur-Average filter is a handy way to remove color cast when you’re new to photo editing. It’s easier than traditional adjustments because you don’t need to work with color channels or hues – the editing program finds the correct color for you.
Is Color Cast Always Undesirable in Photography?
Color cast isn’t always undesirable. Some photographers use it intentionally to colorize a photo and add an artistic effect. This is common in fine art photography, advertising, and marketing.
If you want to create a color cast, you can bounce the light off of a colored object and onto your subject. A piece of neon foam board, a large vehicle, or a painted wall can help you achieve a unique aesthetic.
For most photographers, it’s easiest to add an artistic color cast when you edit a photo. Find the same tools you’d select to remove color cast, and use them to add a tint instead. Simply drag the sliders or adjust the color channels to change the look and feel of the photo.
Whether you’re taking portraits, landscapes, or product shots, color cast is a common issue. Even in a controlled environment, colored light can cast a strange tint on your photos. By adjusting your camera’s white balance and learning how to remove unwanted tones with photo-editing software, you can create beautiful, true-to-life images.
