spyder 4 calibration and prints still too dark

The monitor calibration plays its part with what you see on the screen by ensuring what you see on the screen is what the program sees.

An example:

If a monitor isn't properly calibrated, what might appear as lime green to you the program might think is pine green.  Or neutral gray to you might actually be seen as a gray with a red color shift to the application.

This can cause issues when printing because the program isn't sending to the printer necessarily what you are seeing.  It is sending to the printer what the program sees.  And colors are interpreted as numbers for Red, Green, and Blue. So 255-255-255 is white, 255-0-0 is red, etc.  This is what the program sees.  So if something you are viewing might look to be 50-205-50 (lime green) it may really be 154-205-50 (yellow green).

The calibrator creates what is known as a look up table that interprets what your monitor is displaying to you and what those colors actually are.  So what you might see as 50-205-50 is also seen by the program as 50-205-50.  In turn, this will make colors more repeatable, images will be edited and appear correct on other displays, and print quality becomes more predictable.

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Paul