So recently I had some quick prototyping to do on a Rapsberry Pi, and after connecting the HDMI cable, the colors looked washed out. Areas that should be white were pink, and areas that should be black were green! Didn’t make for good viewing!
The Fix
As suggested by several online sources, the key to fixing this is to edit the /home/boot.txt file. Many suggest you boost the signal being sent from the Pi to the HDMI adapter by uncommenting or adding the line
config_hdmi_boost=4
I tried this, and this did not work. What finally helped was adding the following lines to boot.txt.
sdtv_mode = 2 hdmi_drive = 2
And ofcourse, I also updated the Pi
$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get install alsa-base alsa-utils
Best of luck!