This should give you 1:1 pixel resolution at resolutions above 1920x1200 in Terraria 188.8.131.52.
To clarify, the only thing that this mod does is remove the forced minimum zoom level in Terraria. If you open the options and the lowest value for zoom is higher than 100%, this will let you set your zoom to 100%.
Note that this currently requires that you have the .NET Framework 4.6.1 or higher installed.
The most common complaint appears to be this not running or appearing to have crashed on run. Rebooting, then running RTResolution again, appears to fix this for the vast majority of users.
|Showing 1:1 pixel resolution at 3840x2160 in Terraria 184.108.40.206|