I just started to play with TFT LCD screen with Arduino. I used Itead 2.8? TFT shield which is said to work great with UTFT library. Taking into account that Arduino has too limited Flash to hold a full frame of picture, and that the shield has a SD card socket on the back, I decided to make a SD card picture viewer as my first approach.
My sketch is here.
The 8-bit AVR-based Arduino has not only limited storage but also limited computation power. It is impossible to decode JPEG or PNG on-the-fly with Arduino, nor is it possible to load a whole bitmap from SD card into SRAM. The image files have to be stored in raw data format and loaded and rendered portion by portion. The native data format of the TFT control chip is RGB565 (2 bytes for a pixel, 5 bits for red, 6 bits for green, 5 bis for blue). So I used MediaCoder, which is a free universal media transcoder I developed, to generate the raw image data of RGB565.