You probably already found the answer however not knowing your configuration, I will pass on what helped me through my problem....basically had the wrong HDMI Cable. This MIGHT Help to at least explain what the problem might have been.....
There are five HDMI cable types to choose from, each designed to meet a particular performance standard. Here is an overview of the HDMI cable types, their capabilities, and how to tell them apart.
To help consumer and clarify cable types further, all HDMI cable products will now be required to be labeled by cable type. Look for these labels when choosing the HDMI cable that is best for your needs.
******Standard HDMI Cable
The Standard HDMI cable is designed to handle most home applications, and is tested to reliably transmit 1080i or 720p video - the HD resolutions that are commonly associated with cable and satellite television, digital broadcast HD, and upscaling DVD players.
******Standard HDMI Cable with Ethernet
Sample_Standard_Automotive_HDMI_Cable.jpgThis cable type offers the same baseline performance as the Standard HDMI Cable shown above (720p or 1080i video resolution), plus an additional, dedicated data channel, known as the HDMI Ethernet Channel, for device networking. HDMI Ethernet Channel functionality is only available if both linked devices are HDMI Ethernet Channel-enabled.
******Standard Automotive HDMI Cable
Supports up to 720p/1080i (does not support HDMI Ethernet Channel). Since an automotive system may be wired with one or more internal relays that can affect signal strength, the Standard Automotive HDMI Cable needs to send a stronger signal than other cables types, so it is tested to higher performance standards.
******High Speed HDMI Cable
The High Speed HDMI cable is designed and tested to handle video resolutions of 1080p and beyond, including advanced display technologies such as 4K, 3D, and Deep Color. If you are using any of these technologies, or if you are connecting your 1080p display to a 1080p content source, such as a Blu-ray Disc player, this is the recommended cable.
******High Speed HDMI Cable with Ethernet
This cable type offers the same baseline performance as the High Speed HDMI Cable shown above (1080p video resolution and beyond), plus an additional, dedicated data channel, known as the HDMI Ethernet Channel, for device networking
Talking about the 2012 late mac mini 6,2 and all the minis from late October/November 2012, I think they had an issue with Intel HD4000 graphics, from my perspective I think its a driver/firmware fix, the mini doesn't handle well the HDMI port, I'm tryied several cables and adapters.
And the only workaround I found until this drivers/firmwares are updated to fix this, is to use Thunderbolt to VGA
sadly but true. so my monitor catch the RGB color settings.
anybody with this problem?
Apple/Intel please fix this ASAP