Just put the image you have on the SD card in hex format in an array like this:
prog_char my_image[] PROGMEM =
{
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x40, 0x18, 0xf1, 0xee, 0xab, 0xff, 0xcc, 0xff, 0xee, 0xff,
0xef, 0xff, 0xf0, 0xff, 0xf0, 0xff, 0xee, 0xff, 0xcf, 0xff, 0xab, 0xff, 0x6a,
0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0xf6, 0xc3, 0xfe,
0x6a, 0xff, 0xaa, 0xff, 0xcd, 0xff, 0xcc, 0xff, 0xcd, 0xff, 0xed, 0xff, 0xee
};
And read from there instead of from the file.
Here is a post that does this exactly: http://forum.freetronics.com.au/viewtopic.php?t=5959