Medical　imaging　techniques　like　computed/digital　radiography　(CR/DR)　have　introduced　a　formidably　powerful　tool　in　medicine.　Image　enhancement　takes　an　important　roll　in　the　CR/DR　computerized　analysis　process.　Much　effort　has　been　put　into　the　area　of　image　enhancement.　However,　conventional　multi-scale　methods　have　the　drawback　of　the　introduction　of　severe　visible　artifacts　while　large　structures　are　enhanced　strongly.　This　paper　presents　a　nonlinear　multi-scale　medical　image　contrast　enhancement　method　for　the　improvement　of　medical　image　quality.　More　specifically,　a　novel　nonlinear　enhancement　function　is　proposed　incorporated　with　human　visual　local　perceptual　contrast.　The　proposed　work　provides　the　advantages　of　enhancing　or　preserving　image　contrast　while　suppressing　visible　artifacts.　To　quantitatively　compare　the　performance　of　the　proposed　method,　the　average　local　variances　are　used　as　comparison　criteria.　Results　demonstrate　the　superiority　of　the　proposed　method.　Our　results　show　that　the　proposed　method　has　the　potential　to　become　useful　for　improvement　of　image　quality　of　medical　images.　©2008　The　Institution　of　Engineering　and　Technology.