The Case for Display Calibration
The Case for Display Calibration
By Alan C. Brawn CTS, ISF-C, DSCE, DSDE, DSNE, DCME, DSSP
The “crusade” for display calibration began with the founding of the Imaging Science Foundation (ISF) in 1996, and ultimately led to creating the commercial arm of that group, ISF Commercial. It began with necessity literally being the mother of invention. In this case displays as they were delivered (at best) looked less than optimal, and in some cases looked downright horrible. I will be the first to say that as displays have evolved, so has the performance of the products out of the box. This begs our current question… is display calibration still the necessity that we once thought it was? I may surprise some of you by saying no… but also yes. Please permit me to explain!
By explanation, display calibration is the process of using the display’s internal controls to adjust the on-screen image so that it accurately matches the input source as its creator designed it. This allows the calibrated display to properly reproduce the signals from any source device. This leads me to the “no” part of my answer. If picture performance and true color accuracy are not important to you and as long as the overall image looks fine (at least to you) then calibration is not necessary. However, if you have an open mind on the topic and want to explore options, the decision might go either way. I think I can present a case that display calibration is indeed as important (as it ever was) from several perspectives.
For those of you who think that today’s manufacturers deliver their displays from the factory out-of-the-box calibrated, you are missing three big points. First, manufacturers deliver their displays with brightness and contrast peaked and color saturation set to a highly saturated (and in many cases unnatural) level. Is it accurate? No… but it is intended to be noticed among all the other visual elements to an audience, since our eyes gravitate to the brightest display in the room. Keep in mind that there is a huge difference between attracting attention and holding it. Secondly, the manufacturers have no idea what environment the display will be installed in, and what the content might be. There is no single and universal setting that can embrace the variables of both source and environment that affect what we see on screen.
Let’s start with the environment. All displays work through additive color mixing… this is when we take red, green, and blue primary colors, and those three combined to create secondary colors (cyan, magenta, and yellow), and finally where all six combine to create white light. In a totally dark room, nothing else is added to what we see on screen… however, if the room is illuminated, we are adding several factors to the light and color from the display. This will include the color temperature and intensity of the ambient light, as well as the reflected light and colors from the walls, ceiling, and floor. This combination is how we actually see the image on the display. From the beginning of video projection till this very day, design and integration professionals know that the display cannot be truly optimized until it is calibrated in the location where it is to be installed, and under the lighting conditions of how it will be viewed.
Of course, we may also have different types and brands of displays in a given space. Back in the old InfoComm Shootout days, attendees saw side by side images that were radically different, despite appearing to be the same on paper. Why you ask? Well, in the early days there were different brands of CRT tubes, and each had their own phosphors… so a Barco red was different than Sony or Electrohome red. In the modern digital age, we have more complex DLP, LCD, and LCoS projectors with highly different methods of getting their particular light and colors on screen. For flat panels, LCDs may appear to be somewhat similar, but the construction and filters are not… and both QLED and OLED have their own unique characteristics. The only way to get disparate displays and display technologies to play nice together is to leverage the common language of calibration to a known reference standard. If these images cannot be exact duplicates, at the very least they will be close to each other… and not distract from the overall viewing experience.
When we speak about a standard for calibration, there is the CIE color chart to use as our guide. For HDTV there is the Rec.709 standard. This is very close to the original computer-based sRGB standard used for content creation and the internet. At the high end there is now the Rec.2020 standard for Ultra High Definition (UHD) displays. This standard includes high dynamic range (HDR) with increased brightness and contrast and wide color gamut (WCG). The new standard truly begins to approach what the human eye can see. It is a combination of source material encoding, a high bandwidth signal path to distribute the source, and finally a display designed to take advantage of the expanded performance. It is almost trite to say it, but Coke red must be Coke red and Ford blue must be Ford blue. It is important to the companies and the viewers.
I got some great input from L. A. Heberlein VP of Business at Portrait Displays and CalMAN display calibration fame. He points out that “Color accuracy is a strong indicator of professionalism. Getting it right – starting with knowing what right is — separates the people you want to work with again on the next job from the people you don’t.” He reminds us that “It’s not just about color. Getting the gradation between black and white is even more important, or you can miss details in the too-dark dark areas or the blown out white spaces.” For those who doubt this, look for the new AVIXA ANSI Image System Contrast Ratio (ISCR) Standard on display contrast. It proves that poor grey scale equals lost information.
Of course, every article on display calibration is mandated to mention videowalls. It is one thing to have a stand-alone display showing iridescent colors and black as a substitute for good grayscale or contrast, and yet another to have a huge matrix of screens with each individual screen looking out of sync image-wise with the others. Kudos to the big purveyors of videowall screens, because most are now including calibration software as a part of their package.
Another benefit of calibration is total cost of ownership or TCO. It is estimated that calibrated displays can offer up to 30% less power consumption, due to optimized screen light output. This can also improve panel life, by up to 30%. If there are only a couple of screens in a facility, then this may not be a factor… but if company wide there are many displays, then the dollar savings can be a significant factor to the operations budget.
The fact is that viewers care. They spend over 10 hours each day interacting with screens of one type or another, and the vendors of those screens have trained viewers to notice and care about picture quality. Calibration improves the ability of a message to conveyed. Displays that provide a proper amount of brightness, contrast, and color to deal with the environment are easier to read, and natural colors make the displays more appealing to watch. Research shows that a calibrated display can increase recall by as much as 30%! Any AV or digital signage integrator would be wise to make display calibration services a part of every installation. It is a clear differentiation from many competitors and provides a level of professionalism that is all too often missing in our plug and play world. It is a recurring revenue stream and a way to keep in touch with a client.
I don’t know which side of the question of the necessity for calibration that that you may ascribe to… so here is a little homework. Go to a trade show, or a big box store, or your local sport bar and look at the displays. Look at the colors you see on screen and think how they compare to what you see in nature. Then you can make up your mind about calibration!