Screen Orientation - avanc/photOS GitHub Wiki

Depending on your needs, photOS can also be configured to show the images in portrait mode.

The following commands are executed on the device, so login into it:

> ssh root@photos-xxxxxxxx
> mount -o remount,rw /boot

Find the corresponding rotation in the official Raspberry Pi documentation and add it to /boot/config.txt (e.g. 90 degree clockwise):

.
.
.
display_hdmi_rotate=1

Thereafter, reboot the device:

> reboot

config.txt is located on the first partition, if you want to change it directly on the SD-Card with your computer.