Abstract: In this paper,a content-based adaptive contrast enhancement using sub-block processing was presented,which can flexibly process a wide range of image with various features．It can meticulously process image by analyzing local characteristics and operating in sub-block．We generated an enhancement function with adjustable parameters,which can be used to process various images flexibly through adjusting the parameters．Instead of adjusting these parameters manually,the proposed algorithm can obtain the reasonable enhancement parameters automatically through extracting the relevant characteristics from local content of image．In this way,various images can be adaptively processed without manual intervention．Experimental results demonstrate that the proposed method can flexibly enhance various images,such as underexposure,overexposure,back-lighted,misted,even mixed several characteristics above-and produce ideal enhanced images.

Key words: Contrast enhancement,Overlapped sub-block,Adaptive processing,Content-based