Was closed without a solution.
The proposed solution was to contact Dell to tweak the driver. However this idea is a dead end. I've reported several issues to Dell and they fixed exactly zero, that is an unreliable company, and the problem is not going to get solved this way.
I propose that Intel adds an option to toggle which YCbCr or Color Saturation the user wants, and this can be tweaked in Intel Graphics Command Center easily by the user. Having to tweak the user registry is not user friendly at all, who would want to do that? (and it doesn't work anyway).
I'm sure Dell uses your Generic Driver with only minor tweaks applied to it. So if this option is integrated into Generic Driver, then it would find its way into driver provided by Dell. This way the problem would get solved for all users, those using Generic Driver and those using Dell Driver.
Thank you for posting on the Intel® communities.
I would like to mention that what Andrew G. mentioned on the original post is accurate, this behavior is expected since the graphics driver will read the xvYCC or YCbCr capabilities reported by the display when connected via HDMI and depending on Original Equipment Manufacturer (OEM) configuration it will turn it on by default. When xvYCC or YCbCr is detected then Saturation is not used as these options are mutually exclusive.
This is the way that the driver has been designed to work when using HDMI® the only way to get this option would be to either get the OEM (DELL™) to modify the driver so it auto-disable YCbCr on supported displays instead of auto-enable.
Having said that this is not considered an issue but the default behavior might be changed but this requires direct support from your OEM also we will share your feedback.
Intel Customer Support Technician
A Contingent Worker at Intel
Dell is not going to lift a finger, so as I mentioned before the proposed solution is a dead end, and does not solve my problem.
I really think an easy to use button/toggle should be implemented into the Intel Graphics Command Center along with Intel Driver, this way it would make its way into Dell Driver eventually.