I know that using special video output cards is a standard in the industry. I know that they bypass OS and video card color management and therefore should provide clean signal.

But what exactly does OS change? How exactly video card can affect video signal?

I would like to get into nitty-gritty details, but I cannot find any hard sources on the Internet.

If you use ColourSpace to profile the same display connected to both outputs in turn, you will immediately see the differences.

Steve

What kind of differences? Gamma, color shifts? Is it the same on Linux, Windows and Mac?

Fedor_Color
The differences will depend on what is active in the OS colour management.
It may be small errors, or it may be large differences.
The issues are related to the operation of ICCs, as well as VCGT, and in Mac issues with Color Sync.
See: https://www.lightillusion.com/what_is_wrong_with_iccs.html
And: https://www.lightillusion.com/direct_profiling.html

Hence why you need to test to see what specific issues you have on any given PC.,

Steve

Light Illusion
Thank you for the links! It is exactly the information that I looked for!

I get now why ICC profiles are inferior to proper 3D LUT calibration, and what correction video card could apply to the output (VCGT 1D LUT).

But ColourSpace can calibrate a display, using video card output. In order to do this, user need to delete any ICC profile that is installed in the system and override VCGT 1D LUT with SpaceMatch, assuming we are using Windows system. Have I understood it correctly?

Would it be then possible to use direct HDMI output to the display? Or is Decklink or other output card still a better way to go?

For actual colour critical video workflows you always need a dedicated video card.

Steve

Steve

Should we have two video cards in the system: one for processing and one for output? Or just one dedicated video card with HDMI output?

Will this be sufficient for color critical workflow?

Thank you for your answers and time!

You really need to discuss this with BMD.
We are not Resolve specialists.

Steve