Contrast enhancement using non-overlapped sub-blocks and local histogram projection

Contrast enhancement regarded as a significant branch of image processing, not only enhances human perception of details hidden in the scene, but also improves the rapid recognition of interested targets. In this paper, a non-overlapped sub-blocks and local histogram projection based contrast enhancement (NOSHP) is presented. First, the original image is segmented into numbers of non-overlapped sub-blocks where the histogram projection (HP) is then executed individually. Subsequently, each sub-block is related to its adjacent three ones by certain weights, so that the integral image and local details can be both enhanced. Experiments in this paper approve that NOSHP can effectively enhance the local details as well as properly preserve the image brightness to avoid the annoying blocking effect and wash-out effect. Moreover, this algorithm can dramatically reduce the time consumption in practical use, leading to a useful real-time processing method well suited to the consumer electronic products.