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What is Color Management?

Posted by Smith Micro Blogger on Aug 1, 2016 11:15:12 AM

Color management is a constant challenge for digital artists. Good color management ensures the correct colors are displayed on both your monitor and on printed photos. In this interview, Benedikt Hartmann, a color management expert, explains how to do this:

Benedikt, you are an expert on color management in Germany. Few have given more lectures on this subject in recent years than you have. Are your listeners exclusively professionals?

No, the audiences are very mixed. While professional photographers are certainly among them, everyone has one basic thing in common: a love of photography and a desire to present their images with consistent colors, from screen displays all the way to printing. After all, the monitor is the window to my photographs, so they need to be correctly displayed in order to avoid errors in image editing and unnecessary publishing costs.

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Screen calibration appears to be a complex issue at first glance. Don’t amateur photographers find it overwhelming?

Not at all. Calibration is carried out automatically and should be repeated every two to four weeks, as modern LCD and LED monitors’ displays change again after a certain period of time. The process itself takes just a few minutes. 

It is often said that laptops cannot be calibrated and that Windows is completely unsuitable for true-color images.

Again, I have to disagree with that. While there is no doubt that a laptop monitor does not have the same display options as a professional image-editing monitor, a great deal of the technology has changed. In any case, it is useful to have an accurate color display on your laptop monitor too. What’s more, displaying colors accurately is just as easy on a Windows machine as it is on a Mac.

What actually makes a good sensor?

There are a few key points to consider here. Firstly, the meter should have no gelatine filters, as these age very quickly and give incorrect results after a short time. The variability of the sensor should be very low, and the device should be capable of measuring the largest possible screen area. This will prevent faulty measurements caused by defective pixels on the screen.

Are there any details to bear in mind when it comes to software?

The software should support hardware-calibratable screens. This means that the color profile would normally be written on the computer’s graphics card. Some screens also have their own integrated LTU, meaning the profile can be loaded directly onto the monitor. The software should detect this and load the profile on the screen. This is much more accurate. In addition, the software should offer the possibility of directly adjusting the brightness of the DDC protocol. Of course, this only works if the monitor, graphics card and cable all support this standard, but most do.

What settings should the software have?

Presets such as ‘Photography’, ‘Web’ or ‘Print’ should be available. For image editing or viewing, simply select the ‘Photography’ preset. If you want to know in advance what your printed images will look like, then select the ‘Print’ preset. Professionals should be able to select all these parameters independently.

What is the difference between each of these presets?

In principle, there are three key factors to consider when calibrating: brightness, color temperature and luminance. It is generally standard to calibrate a monitor to a brightness value of 120 cd, as screen quality tends to be best in this area. If the screen brightness is set too high, it can give rise to color loss, in the same way that turning the volume up loud on a stereo system makes the music louder but also makes it much harder to hear its nuances. The color temperature should be set to 6500K for image editing purposes. This corresponds to daylight in the shade, which brings us to one of the differences in presets. Photos are generally displayed indoors, where the color temperature is usually around 5000K. For this reason, it makes sense to view the image at 5000K before printing. When it comes to setting luminance, the ‘Gamma 2.2’ setting has long been regarded as the benchmark, and I have been recommending this setting for years. On closer inspection, however, this is no longer correct. This value has its roots in the early days of television technology. Television cameras were weak at capturing shadow areas, which meant that CRT televisions were artificially brightened in these areas. This is no longer necessary. It is better to calibrate the brightness distribution based on Lstar, which corresponds to the human perception of color. However, as I have already mentioned, software automatically assumes these settings in presets such as ‘Photography’, for example.

With that in mind, how can room lighting be achieved?

The rule of thumb for this is that the screen should be the brightest light source in the room. Calibrating the screen to match the brightness of the light in the room is essentially nonsense. If the light in the room is extremely bright, I would also need to turn up the brightness on the monitor, which leads to color loss. While the perfect environment is obviously desirable, it is often impossible to achieve in practice. When editing images, for example, it is best to simply draw the curtains.

Do you have any tips for image output?

Of course. Before the output, it is important to calibrate the screen with the “Print” preset. Good service providers make their print profiles available for download. These profiles can then be integrated into the display in Lightroom, for example, in what it calls ‘soft proofing’. The display is restricted to exclude any values that cannot be printed. If I can still see outlines in the shadows when displaying the image normally and then run it through soft proofing, I still have the opportunity to brighten the shadows in my photo. Although the presentation of my image would then appear incorrect on the screen, it would print correctly. The screen is an illuminated medium that generally makes images look brighter and more vibrant, while print is a reflective medium that makes photos appear somewhat darker. Slide photographers know this all too well, as the proof on the slide never corresponds with the projected image. I can now counteract this effect by calibrating my monitor and soft proofing. This also applies to inkjet printers, where color profiles are installed with the driver and can be directly incorporated into the display. This makes it possible to select the best paper for your photograph in advance, saving you both time and money.

So who should calibrate their screen, and is it also possible to set up the display correctly without a meter?

Anyone who takes photographs should calibrate their screen. Unfortunately, this is only possible with a meter. Sadly, man is not a reliable light meter, as one simple example demonstrates. In a room with fluorescent lighting, we see all colors correctly, but our brain corrects them automatically. This is bad news when it comes to determining color values. An additional problem is that monitors do not have detailed setting options. This is possible only through a color profile, which can only be created by software.

Many thanks for the interview, Benedikt.

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