Why do I need to do calibration myself?
Generic profiles are usually bad. When a manufacturer creates a new model, they just take a few items from the production line and average them together:

Display panels differ quite a lot from unit to unit and change substantially as the display ages. It is also more difficult for printers, as just changing the type or weight of paper can invalidate the characterization state and make the profile inaccurate.
The best way of ensuring the profile you have is accurate is by doing the calibration yourself, or by letting an external company supply you with a profile based on your exact characterization state.
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See Also
- How do I assign profiles to devices? — Look in System Settings ▸ Color for the option to change this.
- What's a virtual color managed device? — A virtual device is a color managed device that is not connected to the computer.
- Where do I get color profiles? — Color profiles are provided by vendors and can be generated yourself.