Censorship is usually seen as an act against the author's will. Talking with an editor in my country (Italy) working for a publishing house in the erotic manga market, he tells me that censorship for erotic manga is done in two verses: removing censor bars and obfuscation necessary in Japan (decensorship) and removing elements not suited to Western audience or in a gray legal area, e.g. child nudity. Both of those censorship and decensorship are done with the author consent, becoming a self-censorship and generating a new derivative work featuring important changes.
Shortly: is censorship of manga always done with author consent both in erotic and mainstream publications during localization? Is there a common practice around the world on this topic about manga localization? Are there any cases of censorship of manga publications done without author consent in Western countries?