Hi Xander, thanks for your help.
Right now, I'm using ArcGIS 10.2.1, in this release there are many improves to the arcpy library.
Then doesn't exist any method to load an image in a RASTER field with python, may be something similiar how read the image, compressed, and save it in the Raster field?, because I need to do it for that way. It doesn't matter if I need to switch to a file geodatabase.
Best regards,
Andrés Santos