Answer
The following file types are supported in MapObjects as images:
ARC/INFO Grid (hdr.adf)
ADRG - Arc Digitized Raster Graphic (*.img, *.ovr, *.l)
ASRP/USRP
DIGEST ASRP, A NATO Military format (*.img, *.ovr, *.l)
BIL
Band interleaved by line multiband images(*.bil)
BIP
Band interleaved by pixel multiband images(*.bip)
BMP
Windows bitmap (*.bmp, *.dib)
BSQ
Band sequential multiband images (*.bsq)
CADRG
Compressed Arc Digitised Raster Graphics(*.*)
CIB
Controlled Image Base (*.*)
CRP
Compressed Raster Product - Military GeoTIFF (*.tif)
ERDAS IMAGINE (*.gis, *.lan)
GeoTIFF
TIFF with a Geo header (*.tif, *.tff, *.tiff)
GIF
Graphics Interchange Format (*.gif)
IMPELL RLC
Run-length compressed files (*.rlc)
JFIF
JPEG (*.jpg, *.jpeg)
MrSID
Multi-Resolution Seamless Image Database(*.sid)
NITF
National Imagery Transfer Format (*.ntf)
Sun rasterfiles (*.rs, *.ras; *.sun)
SVF
Single Variable File (*.svf)
TIFF
Tagged Image File Format (*.tif, *.tff, *.tiff)
For additional details, refer to the MapObjects Help topic "images".