I was working with a top commercial photographer last week. He’d paid for some colour management training and I also profiled his printer for him. Like most photographers his studio was littered with camera bags and Peli cases containing very expensive camera bodies and lenses. So I was surprised to see that he was using an iMac as his main screen for image editing. Not only that but when I came to train him how to calibrate it with his ColorMunki Photo he admitted that it had some serious problems. The lamination of the layers in the screen was uneven, leading to some odd blotchiness across the screen. It was out of warranty so Apple wouldn’t fix it. I swapped the desktop picture to a plain grey and showed him the screen also had a magenta cast that began in the centre of the screen and grew worse towards the right-hand edge.
This guy was a very good photographer with very good clients and top of the range camera gear and yet he was working with a monitor that was clearly not fit for purpose. I’ve come across this many times with other photographers, graphic designers and pre-press companies. They see a monitor as merely something to attach to a computer and don’t consider the quality or the accuracy of the image that they are seeing. True, any screen can be calibrated and profiled with a Spyder or something similar but the underlying quality of the monitor has a huge influence on the accuracy of that calibration. If you want to make a silk purse it pays to start with some silk and not a pig’s ear.
I used to be in the business of selling high quality monitors but I’m not any more. That doesn’t mean that I see them as any less important in a colour managed workflow though. Choosing the right monitor for the task in hand is as vital as choosing the right lens for a photographer or the right typeface for a designer. Of course not every user needs to invest in a top quality display if what they are doing isn’t colour critical, and not every user can afford the display that they really need, but everybody doing any kind of image or video editing should be aware of the five factors that differentiate a monitor designed for colour correction from those designed for general home or office use.
1. Colour Gamut
Like any device that reproduces colour a monitor has a defined range of colours that it can display. This range is set by the actual colour of the red, green and blue pixels in the LCD panel, as well as the backlight technology used and a few other factors like internal software settings. Most monitors, including iMacs, have a colour gamut similar to a colour space called sRGB (see this post for more details). sRGB is a great colour space for viewing web pages and word processing but not so great if you are editing images. sRGB is much smaller than the colours that a digital camera can capture and it is smaller than the colour space of a printing press or good inkjet printer.
One or two monitors aimed at image editing are only sRGB but the vast majority are closer to the Adobe RGB (1998) colour space. Adobe RGB was developed by Adobe specifically to encompass more of a typical printing press colour gamut. Adobe RGB is also close to colour gamuts used in the movie industry like the DCI colour space. Having a monitor with a wider colour gamut can allow you to see more of the colours that are in your images, and give you a better chance of getting a good match between monitor and print. The limit of current monitor technology is about 99% of Adobe RGB. Emerging technology such as OLED could push things further.
LCD monitors are made from layers of different materials sandwiched together. The illumination that shines though the LCD matrix nowadays comes from arrays of LEDs, sometimes only on the edges of the panel. LCD technology is pretty much inherently non-uniform. Every LCD screen has some degree of uniformity problem. There can be areas that are lighter or darker and even some colour shifts. Sometimes, like with my customer’s iMac, the problem is very visible. In other cases it’s harder to see and may only come to light when the uniformity is measured with a colorimeter or spectrophotometer.
Only a couple of companies actually manufacture LCD panels. Most monitor manufacturers buy their panels from LG or Samsung. These companies produce different grades of monitors from cheap TV panels to the highest medical grade panels. As the cost of the panel goes up so does the care taken in manufacture along with the quality of the components and hence to some extent so does the uniformity. More expensive, higher quality monitors have more expensive, higher quality panels. However, that isn’t the end of the story. When companies that make good quality monitors take delivery of the panels they aren’t all uniform. The average uniformity will be better that a cheap panel but what really sets a quality monitor apart in terms of uniformity is the further measurement and correction that then takes place. The monitors are measured for uniformity and any variations found are compensated and corrected for. Corrections are stored in the monitor to even out the variations and the top of the range models often have to conform to tight uniformity tolerances.
Having a screen that is as even as possible from edge to edge is very important if you are editing images or grading videos, otherwise you could be missing problems like colour casts or correcting ones that aren’t there.
3. Quality Assurance
Uniformity isn’t the only test that a good monitor goes through. They are also measured for their tonal reproduction (gamma) so that they display tones very evenly. Corrections for the gamma are stored in the monitors firmware in special look up tables. The resolution of these tables are often higher than standard monitors. Many cheap monitors have 8-bit look up tables whereas a monitor designed for image editing will have 14 or 16 bit tables. This means the tones will be more accurately reproduced leading to very smooth gradations and generally more accurate colours.
Good quality monitors will also often have sensors and corrections for internal temperature and back light ageing to ensure consistency over time. Monitor resellers and manufacturers will often tout a whole series of numbers such as resolution, contrast ratios, maximum brightness etc but to really get the measure of a monitor you have to read a little deeper and look for the qualitative differences.
A long warranty in itself isn’t a measure of quality. You only have to look at the car market for proof of that. However, a long warranty is an indication of the confidence a manufacturer has in its products and its commitment to customer service. Also because quality monitors are more expensive a long warranty reassures you that you are making a sound investment and can mitigate the higher cost. I’ve had customers go through a two or three cheap panels used only for palettes during the lifetime of their main screen used for image editing.
Accurate calibration and profiling is as important for a high quality monitor as a cheaper one. I’ve often had customers with quality screens think that they don’t need to calibrate them, this myth is reinforced by some manufacturers on their websites saying that their screens are factory calibrated. They may be but good colour management is about consistency, stability and control and the only way to guarantee that a monitor remains as accurate as the day it was made is to regularly calibrate and profile it with a good colorimeter or spectrophotometer.
The best image editing monitors come with their own calibration software that can adjust the screen directly with the high bit look up tables I’ve already mentioned. This direct hardware adjustment obviates the need for any manual screen adjustment. Some monitors now even have built-in colorimeters so that the whole calibration process can be automated.
The Whole Package
I’ve come across plenty of wide gamut monitors I wouldn’t consider fit to edit images on. I’ve even used some calibration software supplied with monitors for hardware calibration that haven’t given very good results. No single one of the factors listed above are indicators of a quality image editing monitor but they should all be on your list of things to look for and the more of them you can tick off the more likely you are to have a good monitor; one that you can trust to make colour judgements on.
One factor some of you may be surprised that I haven’t listed is resolution. There have been a rash of 4K, UHD and 5K screens released in the last year or so but the number of pixels is not an indicator of monitor quality. If you are looking for a high res monitor the above five factors still apply.