Methods to automatically convert graphics into tactile representations have been recently investigated, creating either raised-line or relief images. In particular, we briefly review one raised-line method where important features are emphasized. This paper focuses primarily on the effects of such emphasis and on comparing both raised-line and relief methods (produced by a Tiger Braille printer) through psychophysical experiments including discrimination, identification, and comprehension (involving 14 sighted and 6 blind subjects). Results show that raised-line pictures outperform relief images in all three tasks. Also, emphasizing important features significantly increases comprehension of tactile graphics. Raised-line images, however, disregard intensity/colour information unlike relief pictures. A technique incorporating intensity into raised-line graphics is also presented. Further experiments show the validity of this technique. (Contains 11 figures and 3 tables.)