It is also recommended to use SKSE to enable high-resolution warpaint:
1) Download and install Skyrim Script Extender (SKSE) (1.6.6 or later)
2) Check the Data folder and create the SKSE folder if necessary
3) Check the SKSE folder and create the SKSE.ini file if necessary
4) Open SKSE.ini
5) Add the following entry to the .ini file if necessary