Color and contrast correct notebook?

How can I do this without such a thing (picture)?

I'm not sure how to do it "perfectly" without such a device, but I got the message that some of them can be borrowed for a fee. Maybe that's an option too.

That "thing" is why the calibration works in the first place. The device can calibrate your display to an exact value. Without it, you'd have to judge whether your screen is calibrated enough.

Can you perhaps borrow them in electronics stores for at least very little gel? So, for example, you drive into the store, pay a ten, calibrate the screen and leave.