Color enhancement of low exposure images using histogram specification and its application to multiple color filter aperture camera

This paper presents color enhancement of low exposure images using histogram specification and its application to the p re-processing of a multiple color-filter aperture (MCA) camera which can estimate depth information of objects at different distances and perform multifocusing. Insufficient amount of exposure is the fundamental problem of the M CA camera because of the fixed and finite-sized apertures. The image acquired by the MCA camera cannot avoid the low-exposure and low-contrast degradation. The proposed color enhancement algorithm analyzes the low exposure phenomenon of a particular aperture, and improves the contrast and performance of the registration process in the MCA camera system. The proposed method can enhance the contrast of any low-exposure color images acquired by a conventional camera, and it can also be used to improve the image registration performance of the MCA camera. As a result, it can be incorporated into multifocusing, extended depth of field (EDoF) systems, and real-time 3D reconstruction.