An advanced contrast enhancement using partially overlapped sub-block histogram equalization

In this paper, an advanced histogram equalization algorithm for contrast enhancement is presented. Histogram equalization is the most popular algorithm for contrast enhancement due to its effectiveness and simplicity. Global histogram equalization is simple and fast, but its contrast enhancement power is relatively low. Local histogram equalization, on the other hand, can enhance overall contrast more effectively, but the computational complexity is very high due to its fully overlapped sub-blocks. For high contrast and simple calculation, a low pass filter type mask is proposed. The low pass filter type mask is realized by partially overlapped sub-block histogram equalization (POSHE). With the proposed method, the computation overhead is reduced by a factor of about one hundred compared to that of local histogram equalization while still achieving high contrast