If your images are photos or complex drawings, it is best to store on SD card.
I have already explained that RAW files are simpler. (and smaller than 24-bit BMP)
Adafruit_TFTLCD library comes with BMP examples. (only for 24-bit BMP)
I suggest that you quote some numbers e.g. size of binary when you build for a Uno (and it complains).
Tick the box for verbose Compile in Preferences.
David.