We could speak french indeed, I known Boeufmironton has little troubles with english ;)
As for chromatic aberration it's a mate of mine who showed me this trick but I wouldn't at all be able to explain what is technically happening there (he did roughly explain to me tho but I roughly forgot all about it), apparently different stuff/process from optical to digital... All I remember is that it can sometimes (not always) reduce the file's weight without affecting graphic details.
Sorry for not being able to enlighten you any further on the subject.
As for chromatic aberration it's a mate of mine who showed me this trick but I wouldn't at all be able to explain what is technically happening there (he did roughly explain to me tho but I roughly forgot all about it), apparently different stuff/process from optical to digital... All I remember is that it can sometimes (not always) reduce the file's weight without affecting graphic details.
Sorry for not being able to enlighten you any further on the subject.