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For strange reasons best not asked, I have a projector plugged into my computer that is pointed at a mirror. So the computer image is displayed on a wall, but it is mirrored.

In Linux(ubuntu) I can go to display preferences and set the external monitor to have a rotated image. Is there a clever way I could have it set to rotate/flip the image?

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I like it when questions get funky. Let me see what i can come up with. So let me understand the image comes out of the projector, bounces on the mirror and lands on a wall? – Luis Alvarado Jan 4 '11 at 0:01
It might depend on the graphics driver you're using. Also, the projector itself might have such an option. – Daniel Jan 4 '11 at 2:26
Yes the image bounces on the mirror and lands on a wall (if I'm honest on a table, hence the wish for a mirror). I first tried finding an option on the monitor. – Gregory Jan 4 '11 at 12:39
It's an option on my projector. I didn't know why anyone would ever use such a setting. Now I know, thanks! – Marc Jun 9 '13 at 15:26
up vote 6 down vote accepted

Ok after testing with 2 PC. I found the following:

On some integrated cards like Intel you can use xrandr in console. For example:

Go to console (Alt+F2 then type gnome-terminal and press ENTER)

xrandr -x will flip de video horizontally like a mirror.
xrandr -y will flip de video vertically.
xrandr -y -x will flip both.
xrandr -o normal will return to normal the video.
xrandr -o inverted will...invert O.o

But if you have (in my case) an Nvidia this will most likely not work. For an Nvidia to work you need to:

Edit you xorg.conf: sudo nano /etc/X11/xorg.conf

Finde the section that has Driver "nvidia" in it

Copy and paste the following at the end of that section: Option "RandRRotation" "on"

This will activate the rotation for Nvidia which comes off by default. Why off by default i do not know.

After that reboot and you can change the orientation BUT NOT the reflection. What i mean with this is that Nvidia does not yet support reflection options like -x or -y options in xrandr. I will keep searching for some more since the question is interesting.

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If you are testing this sort of thing without the mirror set up, then I suggest first entering xrandr -o normal so you can press up,up,enter without twisting your head. :) – Gregory Jan 4 '11 at 12:47
I like your attitude to funky questions. Using xrandr -x worked, but it would turn off the primary monitor (which I wanted to use unflipped). Anyway you led me to xrandr --help and after some thinking came to the following command which does what I want. xrandr --output VGA1 --reflect x – Gregory Jan 4 '11 at 12:48
I just spent entirely way too much time playing with this and laughing manaically. I think I have spent too much time in front of my screen today. – Wayne Werner Jan 21 at 19:35

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