In the field or in the office, a properly calibrated monitor is key to delivering quality work. By following a few simple steps to calibrate your monitor, you can ensure what you see on your screen is what your footage really looks like.
Having a color balanced monitor may not seem all that important especially if you’re in a rush to get the shots you need, but having a color balanced monitor while you’re shooting can save you hours of post production work and even improve the quality of your finished production. In post, a properly adjusted monitor is the only way to know what your footage and finished work really looks like. We'll examine what affects color accuracy in monitors and look at calibration methods so you can achieve the best color reproduction for your projects.
It’s About the Light
Part of the calibration of a monitor is adjusting it to the ambient light around it so the color and contrast are as accurate as possible. Just like a camera that has to have its exposure and white balance adjusted when the light changes, your monitor will need to be readjusted when the light around it changes. This is why, on big feature films, the digital image technician (DIT) who is responsible for the accuracy of the video monitors on set often sits in a tent that blocks out the outside light; likewise, many editors and colorists work in rooms without windows to help control the ambient light.
Types of Calibration
Monitor calibration is done by one of two methods: qualitative or quantitative. Both have their own advantages. Qualitative calibration relies on the user to look at the screen and make adjustments based on what they see. This leaves open the chance for human error, but it is often a cheaper and quicker calibration method. Quantitative monitor calibration relies on a colorimeter that’s used to measure the light from the screen and guide the user through calibration; it also may be used in a system where calibration is automatic. Quantitative calibration, on average, is more accurate; it can be a slow process though, and for some monitors, the hardware needed to calibrate is extremely expensive.
What Monitors Do I Need to Calibrate?
Ideally, any monitor you’re using while shooting or in post should be calibrated so that you don’t have to worry about making a decision based on looking at an inaccurate screen. Realistically, you’ll always need at least one monitor for your post-production that is calibrated, and you should have one, whenever possible, while shooting.
Calibrated Monitors for Post-Production
Using a calibrated monitor in post is the only way to know how your video really looks, from your source footage to the changes you make in post to your final renders, but you shouldn’t calibrate your monitor only when you first bring it into your edit suite. It should be re-calibrated anytime the room light changes significantly (including a fresh light bulb or a new lamp) or every few months. Ideally, you should situate your edit suite in a room without windows. If this cannot be avoided, invest in heavy duty blackout drapes; additionally, you may want to consider dark tinted film for the windows. Remember to clean your monitor frequently and keep it free from dust.
Just like a camera that has to have its exposure and white balance adjusted when the light changes, your monitor will need to be readjusted when the light around it changes.
It’s also a good idea to re-calibrate before an important project. Remember, as a monitor ages, it’s reproduction of color can shift. You’ll want to calibrate more frequently on older monitors and monitors that get heavy use.
Calibrated Monitors on Location
As mentioned before, while at first it may seem like a calibrated monitor on a shooting location wouldn’t be necessary for many workflows, it can save hours of post-production work, including having to fix what couldn’t be seen when shooting. If you’re shooting a web video for a company, they’ll more than likely want you to use their logo in the graphics of the finished video. If that same logo appears on a sign or on a product in your footage, they will expect that logo to match the graphic as closely as possible. Using a calibrated monitor on location will help you achieve that goal.
Video Monitors vs. Computer Monitors
Both video and computer monitors have their own challenges in calibration and monitoring. The format you shoot in and the format you deliver in will dictate what type of monitors you use.
If you’re shooting in NTSC HD, which most productions currently are, and your final renders are in NTSC HD, then that is the format you’ll want to monitor in. Professional HD monitors are easy to calibrate and are relatively inexpensive. You may shoot in HD but still finish in SD for DVD or mobile video. In that case, monitoring in SD is a viable option. There are still many old, used, professional SD monitors you can buy very inexpensively; also, many new HD monitors have SD inputs.
Computer monitors use a larger color space than HD video. This can make it a difficult to monitor HD video with a computer monitor because it can reproduce colors that HD video can’t, so the color you see on the screen may not be an accurate representation of what you’re video really looks like. There are interfaces available to let you use a computer monitor as a video monitor but some of these cost more than a professional video monitor. However, a computer monitor is preferable for work that is shot in raw and going to film festivals at movie theaters or to the web to take advantage of that expanded color space.
Before You Calibrate
Check the work area around the monitor. The lighting should be bright enough to work in but not overly bright to interfere with the monitor. Make sure there is no light reflecting on the surface of the monitor. You may need to turn on any equipment that’s around the monitor to ensure that there are no reflections from LEDs or other screens on the monitor when they’re running. Make sure the monitor screen is clean; this may seem trivial, but it can make a big difference.
For video monitors, you’ll need to send color bars to the monitor. On a shoot it is best to get color bars from your camera but you can use the color bars from the monitor if it has that option, or from any device that you can hook up to your monitor and feed color bars, like from a media player, pattern generator or a computer.
For monitors used in post-production, you’ll need additional hardware to send a video signal from your computer to your video monitor that is compatible with the software you use unless your current hardware already supports this option. Most hardware interface makers like Blackmagic Design, AJA and Matrox list the softwares their products work with on their websites. Once you have the hardware you need installed and recognized by your software, it’s just a matter of finding the color bars in the software and sending the signal to your monitor. Color bars are grouped with other test patterns in some software.
Video Monitor Calibration with Color Bars
This is the broadcast standard method to calibrate a video monitor. It’s a qualitative method of calibration so it can be a challenge to calibrate multiple monitors to match each other. Since colorimeters accurate enough for broadcast use are very expensive, the qualitative method remains the preferred calibration choice.
1. Turn on the monitor and allow it to warm up for a few minutes (this will take longer on older CRT monitors).
2. Make sure that your color bars are being sent from your camera, editing computer or other device. Switch to the right input on your monitor to see the bars if you’re not already seeing them.
3. Adjust your monitor’s brightness, contrast, chroma and phase to their midpoints.
4. Notice the three short black bars on the lower right side of the screen below the red bar. These are called PLUGE bars (Picture Lineup Generation Equipment bars). Turn the chroma all the way down so that the image on screen is in black and white.
5. Look at the PLUGE bars. The bar on the left has a value of 3.5 IRE and the middle 7.5 IRE and the right 11.5 IRE. Since 7.5 IRE is the darkest signal that can be in NTSC, you’ll want to adjust the brightness so that the left PLUGE bar and the middle PLUGE bar are the same as the larger black square next to them. The right PLUGE bar should just barely be brighter than the middle and left PLUGE bars.
6. Turn the contrast up all the way. The right PLUGE bar will become very bright. Turn down the contrast until you can just barely see where the bar is again. If the contrast is too high, the white square at the bottom left will start to bleed over onto the adjacent colors; this is very common on older CRT monitors. Turn the contrast down until the white square is well defined again. Now your luma is set; it’s time to work on the chroma.
7. Turn the chroma up to its middle position. Turn the “blue only” button on. Now at the top of the screen you’ll see alternating blue and black bars. For SDI, HDMI and component signals, you’ll only need to adjust the chroma so that the tops and bottoms of the blue bars match. For Y/C (S-Video) and composite, you’ll use the chroma to adjust the outside blue bars and the phase for the inside blue bars until the tops and bottoms match.
Notes: You really shouldn’t be making color decisions based on a composite signal sent to your monitor. Composite video signals lack the quality of color reproduction needed for such work.
If you’re working with a consumer monitor, brightness may be called picture, chroma may be called color and the phase may be called hue or tint. Consumer monitors may not have all of these adjustments and won’t have a “blue only” button so you’ll have to do some adjusting by eye.
Once your monitor is calibrated, don’t change its settings. If you don’t have a waveform, vectorscope or histogram, your monitor is the only guide you have to the quality and accuracy of your video. If there is a change in light that causes your monitor to look a little off or if flesh tones or other colors don’t look accurate, restart the calibration process from the beginning. Also don't forget to perform periodic calibrations on older monitors.
Calibrating a Computer Monitor
Computers don’t use the same color space as HD video so you can’t just use NTSC color bars to calibrate them. There are a number of colorimeters that work in conjunction with software to automatically calibrate your computer’s monitor. Companies like Datacolor, X-Rite and SpectraCal make calibration tools for a number of workflows that range in price from affordable to specialty-only. Some monitors built for color accuracy come with the hardware and software needed to calibrate them.
You can manually calibrate your monitor using test patterns designed for computers. Both the current versions of the Windows and Mac operating systems offer color calibration tools, but these are not ideal for accurate calibration. There is software available with test patterns and guides to help you use them, but for most users it’s a very difficult process. For the small jump in price, most users prefer and get better results from hardware calibration systems.
Calibrating your monitor will help you see your footage more accurately, but it’s not a magic wand. Your monitor will still be limited by the dynamic range it can reproduce as well as the accuracy of its color reproduction. Still, a properly calibrated monitor is the only way to know how your footage looks. With a bit of practice, you’ll be calibrating your monitors in no time and improving the quality of your productions every step of the way.
Sidebar: What You Can’t See Can Hurt You
We’ve all heard the horror stories of the footage someone thought they had while shooting only to find that it was unusable in post because the footage was overexposed. Struggling to maintain proper camera exposure is a common problem. The zebra functions on many cameras are not very accurate, and even on a properly calibrated monitor, it can be hard to see the loss of detail from overexposure.
This is where a waveform monitor can be extremely valuable. On a waveform monitor, you can easily see if the highlights and shadows of your shots are properly exposed. Many higher-end camcorders have waveform options for their LCD monitors; also, built-in waveform monitoring is standard on better on-camera LCD monitors. There are even solutions that allow you to use a laptop or tablet as a waveform monitor while shooting.
Waveform monitors are easy to read and, on some monitors, can even be setup as a graphic overlay on your live shot. Using a waveform monitor can be especially helpful if there’s no way to have a calibrated monitor in the field.