Hello driverr,
Currently the only available OCR software available for your Photosmart C4780 are compatible with Windows Vista & XP. You can however download the software and drivers for the HP Officejet Pro 8600 e-All-in-One Printer and when you're given the option to connect- select connect later, once it is installed your should have access to the software from your Photosmart C4780.
Please let me know if this was a viable workaround for you! :)
Thanks in advance,