>>Try
>>
>>REPLACE DATA2 WITH CHRTRAN (data2,"DE","ED")
>>
>>-to restore, do it again-
>>
>>REPLACE DATA2 WITH CHRTRAN (data2,"DE","ED")
>>
>>this is OK if all you want to do is fuzz it up.
>
>"fuzz it up"
>Interesting point. We don't know whether Moises just wants to degrade the image to a point where it is recognizable but un-usable or where he wants to make it completely scrambled in the encrypted state.....

If 'fuzzing it up' is the objective then the header of any image file would have to remain intact.
But if the intention is to make the image completely unviewable then just srambling the header in a reversible way might do the job.