I am re-posting this topic from the Users board, since it may, indeed, be "too arcane for the normal user list."
Using ImageMagick 6.8.6-Q16 to convert from TIFF to TIFF, it appears that, in the converted file, IM always inserts the TIFF 6.0 metadata tags for WhitePoint and PrimaryChromaticities (if they are not already present in the original file) and populates them with the CIE 1931 x,y values for D65 white and the CCIR 709 RGB primaries, respectively. It appears to do so even if the original image has an embedded ICC profile which contradicts those values.
Is this the intended, default behavior?