Images　of　roads　captured　in　bad　weather　suffer　from　poor　contrasts　and　colors.　It　is　known　that　the　degradation　of　an　image　due　to　scattering　of　light　is　exponential　in　the　depths　of　the　scene　points.　Therefore,　to　estimate　the　depths,　previous　algorithms　using　physical　model　develop　an　interactive　step.　But　the　method　is　limited,　because　it　needs　to　estimate　four　or　more　unknown　parameters　and　select　the　vanishing　point　manually.　In　this　paper,　we　present　a　simple　implementation　based　on　Hough　transform　and　maximum　entropy　theory　to　solve　the　problems.　First,　the　physical　model　is　simplified　to　reduce　the　number　of　unknown　parameters　to　one.　Then,　an　automatic　method　based　on　Hough　transform　is　proposed　to　select　the　vanishing　point.　Finally,　the　maximum　entropy　theory　is　used　to　acquire　the　optimal　parameter.　The　experimental　results　on　real　images　show　the　effectiveness　of　the　approach.　©2009　IEEE.