How to Horizontally Flip a Monitor Display

I've had extensive discussion about the overscan/underscan dilemma with AMD developers who work on the Catalyst drivers.

The basic idea is that AMD would rather underscan some people whose HDMI displays don't overscan, and create too small of a picture (blank spaces around the picture), rather than not underscan and cause people whose displays always overscan (with no setting to change it and incorrect EDID information) to have the desktop display too large. The argument is that if the desktop is too large, then the user can't see where the Catalyst icon is or the start menu, and they therefore can't navigate the UI in order to make the appropriate change. So they are sticking to their guns on underscanning by default on HDMI to ensure that nobody gets stuck with a desktop that's too big for their screen (with UI elements hanging "off the screen").

I don't agree with the policy, but that's the way it is. It also seems to be a fairly unique decision among graphics driver developers, as I can't reproduce the weirdness on a number of other non-AMD devices: Android tablets, Nvidia cards, and Intel on-chip graphics.

There is a way to directly tweak the underscan/overscan on Linux by modifying values in the "PCSDB" (Persistent Configuration Store Database). I don't know what the equivalent is on Windows, or if you can even read/write the settings without using Catalyst.

I can't personally test this solution, but it appears that it worked for people on fairly recent drivers, so give it a shot: go to Tom's Hardware or I'll just re-post it here:

I found a fix for the overscan issue  
Go to the following key in the registry:  
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\video{####....}\0000 
Create a new DWORD: 
"DigitalHDTVDefaultUnderscan" = dword 0x0000 
Note: there might be several {####....} , should be the one with most of the ATI settings. 
Source:http://forum.beyond3d.com/showthread.php?t=62100

Here is a quote from an AMD source (who will remain anonymous) from several years ago about their HDMI underscan/overscan policy. Note that this applies to both Windows and Linux.

The purpose of defaulting to underscan is not so we rely on HDTVs to overscan back to full screen. This would be horrible due to the image quality loss on the downscale by GPU and then back upscaled by TV. Rather, it solves the problem where a TV defaults to overscan and has no mechanism to disable it (many cheap HDTVs). In this case, the TV will overscan the image and so the menus will typically be displayed off the edge of the screen and prevent the user from easily accessing them. The default is purely for usability purposes, and CCC-LE should be able to change it to 0% (or you can use that registry/PCS key to forced default of 0%).

If you have a smart HDTV that tells us if they overscan or not, we will do the right thing and default to 0%. However not many manufacturers properly set that property in the display's EDID so we fallback to the default of underscanning.

Underscanning should only be the default on HDMI. DisplayPort or DVI should not underscan by default.

Try UltraMon. It lets you flip both vertically and horizantally (independently). It also provides a number of other useful features for using multiple monitors.