This has nothing to do with HDMI, and likely nothing to do with your graphics card.
Your monitor has settings to optimize the picture. It's not uncommon to try to make an image appear as if it were of higher contrast by lightening up the brights and lowering the darks. There are also various color "enhancements" to make the monitor look good that will affect things. Disable these features of your monitor, and this problem will go away.