Some images are portrait and other are landscape. When taking photos you probably were trying to get best picture out of it and rotated camera as you found it necessary. Well then after in order to view pictures correctly you need to rotate them. Markus found another great solution. Instead of editing pictures he left rotation job for his frame.
He made a platform with 320×240 graphical LCD attached using servo motor. Images from SD card are uploaded to screen with help of PIC32 microcontroller. Electronics is mounted on prototype board using through hole elements only. Sadly the frame doesn’t support jpeg images only raw. So they must run through python script for conversions. But this process is fast and works automatically. Finally raw image data is taken from SD card analyzed by microcontroller and depending on image scale it is rotated for best view.