Having the same problem but with Canon PIXMA i4700 printer (and appropriate driver).
My test-pages for RGN and CMYK look exactly like those attached in OP by Gumwise Samgee, so there's no point in attaching mine.
The RGB behavior and color-rendition in Lucid (64-bit on my end) was and still is correct.
Confirmed the bug in 12.04 and 13.04 both 64 Bit.
Having the same problem but with Canon PIXMA i4700 printer (and appropriate driver).
My test-pages for RGN and CMYK look exactly like those attached in OP by Gumwise Samgee, so there's no point in attaching mine.
The RGB behavior and color-rendition in Lucid (64-bit on my end) was and still is correct.
Confirmed the bug in 12.04 and 13.04 both 64 Bit.