Multiple exposure integration for restoring all in-focus images
Ryo Matsuoka, Haruki Ishibashi, Tatsuya Baba, Masahiro Okuda · 2015
When taking a photograph of a high dynamic range scene, saturation of pixel values (that is under/over-exposure) often occurs due to the narrower dynamic ranges of commercial cameras. It is possible to solve the problem of the under/over-exposure by generating High Dynamic Range (HDR) Images. The HDR image is generated by integration of multiple exposure images that are taken with different exposure settings. When taking multiple exposure images for the scene that contains dark areas, one often copes it by adjusting one of the three settings: (1) camera's sensitivity, (2) exposure time, (3) lens' aperture, in order to compensate shortage of the quantity of light. Each of the three methods has a drawback. The high camera sensitivity enhances noises as well as signals. The long exposure causes motion blur. The lens with wide aperture yields out-of-focus images. The first two problems can be solved by denoising and deblurring, respectively, and there are many methods for solving the problems. Our aim is to address the third problem. We generate an all in-focus image without the under/over-exposure and out-of-focus areas due to the wide aperture by integrating the multiple exposure images. We introduce a new technique for image integration which simultaneously addresses the problems of the under/over-exposure and defocus. The validity of the proposal technique is shown by comparing it with several conventional methods for real scenes.