Use HyperRam or HyperFlash as a screen buffer was previously demonstrated in pure assembly:
Now, I've converted the code to Spin2 (although still mostly assembly).
It also works with both PNut and FastSpin.
This loads up an embedded bmp file into HyperRam and then reads into a line buffer, coordinated with VGA driver.
Update: The HyperVGA_640_x_480_8bpp_3f.spin2 example can load 2 images from uSD and then flip between them on display.
Update2: The HyperVGA_8bpp_3i.spin2 example can flip back and forth between two images on uSD, up to 1080p.
Update3: The HyperVGA_8bpp_4a.spin2 is much like the above with a fixed timeout issue in FSRW so that several seconds can elapse between images. There's about a 1 second of white between images, while loading.