So if I take someone's photograph and use ImageMagick to convert it to black and white, by your rationale it would not be covered by the copyright on the origin

So if I take someone's photograph and use ImageMagick to convert it to black and white, by your rationale it would not be covered by the copyright on the original photo? Like someone said, it is a derivative work. The copyright act says: A “derivative work” is a work based upon one or more pre-existing works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications which, as a whole, represent an original work of authorship, is a “derivative work”.