Low　illumination　image　has　the　characteristics　of　low　overall　brightness,　contrast　and　signal-to-noise　ratio.　The　classical　image　enhancement　algorithms　have　limited　enhancement　effect　and　need　to　adjust　parameters　manually.　In　this　paper,　a　deep　full　convolutional　coding-decoder　based　on　U-type　network　is　proposed　to　solve　the　problem　of　low　illumination　image　degradation.　The　experimental　results　show　that,　compared　with　the　existing　mainstream　image　enhancement　algorithms,　the　proposed　algorithm　can　improve　the　brightness　and　contrast　adaptively,　avoid　artifacts　on　image　edges,　and　further　improve　the　objective　evaluation　index　and　subjective　evaluation.　©　2020,　Springer　Nature　Singapore　Pte　Ltd.