The image formats Qt supports by default are:
Format Description Qt's support
BMP Windows Bitmap Read/write
GIF Graphic Interchange Format (optional) Read
JPG Joint Photographic Experts Group Read/write
JPEG Joint Photographic Experts Group Read/write
PNG Portable Network Graphics Read/write
PBM Portable Bitmap Read
PGM Portable Graymap Read
PPM Portable Pixmap Read/write
XBM X11 Bitmap Read/write
XPM X11 Pixmap Read/write
So you'll either have to write a custom Qt image plugin, or somehow convert the image data to one of the formats Qt understands.