Sure, provided that:
1) It's not an unmanaged raster catalog (in which case the source rasters still exist as is),
2) The source hasn't been mosaicked into the geodatabase (in which case you'd need to
know the source bounds to clip it back out again)
3) A lossy compression algorithm hasn't been used (only LZ77 is lossless)
4) Some other process hasn't been run which changed the source data (reclassification,
pixeltype expansion, etc)
5) Your export client (usually ArcGIS) supports export to the original format
- V