Monitor Calibration Targets
In technical jargon, the term „calibration target“ or „calibration goal“ is frequently used. This refers to the data towards which calibration is performed: white point, brightness, and brightness distribution (gamma). In better calibration software, users can choose these targets themselves; whereas cheaper solutions are fixed to common standards.
For brightness distribution, a gamma of 2.2 or alternatively the so-called sRGB curve (which is very similar to gamma 2.2) is generally recommended. Nothing else makes sense on computers today, even if one prefers to work with a gamma 1.8 color space.
When it comes to calibrated gamma, the primary concern is brightness compatibility with operating system graphics and software that operates without color management (e.g., Office programs). Once color management is in play, gamma is automatically adjusted. While calibrating to the gamma of the preferred working color space (if it deviates from 2.2) may offer minimal quality advantages in monitor display and is still occasionally practiced in professional settings, it generally has more disadvantages on normal computers that are not solely used for image editing.
Overall brightness should harmonize with ambient lighting; meaning, in a brightly lit room, the monitor should shine brighter than in a dimly lit back room, so the eye doesn’t have to adjust excessively when looking at the screen. A standard value for averagely lit rooms ranges from 100 to 140 cd/m², while in poorly lit rooms, 60 to 80 cd/m² may be appropriate, and in some very bright rooms, even 400 cd/m² (the maximum of most monitors) may still be insufficient.
Unfortunately, one often encounters „recommendations“ for a specific brightness level. These should be disregarded. There’s no technically justifiable reason why the monitor, for example, needs to be set brighter or darker for editing print images versus web images. The only thing the monitor brightness should be adjusted to is ambient light. Some calibration devices can measure ambient brightness beforehand, providing a good reference point—assuming this brightness remains relatively constant throughout the day (or at least during planned image editing times).
Ideally, the color temperature should also be matched to the color of the ambient light. However, this is often not possible due to changes in natural daylight and the switch to artificial light in the evenings. In such cases, relying on the adaptability of the eye is preferable. The color temperature of the monitor then becomes a matter of habit. Good calibration software allows users to specify any desired color temperature or maintain the monitor’s native color temperature (which is recommended for budget monitors and notebook displays to minimize losses through color conversions).
The most common standard is D65 (6500 Kelvin), which roughly corresponds to direct sunlight. Alternatively, the slightly warmer standard D50 (5000 K) is also suitable. 5800 K is also popular as a compromise; if no standard light is available, the white point doesn’t need to exactly match a standard. If the monitor has a relatively high native color temperature, one can even calibrate to D75 (7500 Kelvin); initially, it may seem cool, but ultimately, it’s just a matter of habit.
D65 (6500 K) is also the defined white point of sRGB and AdobeRGB—which is practically irrelevant, as the white point of the working color space is merely an invisible conversion intermediate. Therefore, there’s no need, nor particular advantage, to calibrate the monitor to D65 for using sRGB or AdobeRGB. Nevertheless, many calibration programs offer such presets and act as if there’s a sensible connection.
Calibration to the working color space? Another formulation occasionally encountered online is someone stating they have „calibrated their monitor to sRGB.“ This implies working without color management and instead fixing the monitor to a specific working color space. This is also referred to as „color space emulation.“
There are specialized programs that allow for the technical adjustment to fixed working color spaces. In practice, this method is mainly applied to projectors and televisions; further information can be found in home theater forums. The process requires a lot of time and specialized knowledge; moreover, only a few computer monitors have the necessary settings in their menus (e.g., a 6-axis correction).
The color space emulation remains a procedure for special cases (e.g., demanding video editing). Otherwise, calibrating to a predetermined working color space is usually not meaningful, and it’s not even provided for in ICC color management. Doing so would limit the monitor’s color space from the outset, rendering it unusable if a larger working or device color space is required.
Common calibration/profile programs that perform „software calibration“ via the graphics card’s LUT inherently do not support color space emulation; if at all possible, it can only be achieved through hardware calibration (or manually, albeit tediously).
A typical calibration according to ICC color management always focuses on white point, brightness, and brightness distribution/gamma as calibration targets. It leaves the monitor’s color space unchanged in size. Adjusting the monitor and working color space is always the responsibility of the application program and needs to be done repeatedly. Therefore, even after calibration, the monitor cannot inherently display the colors of a file „correctly“; it still requires an ICC monitor profile and an application program with color management function.
Source: https://fotovideotec.de/farbmanagement/18_monitor_kalibrierungsziele.html
