Denighting: Enhancement of night time images for a surveillance camera
A.Yamasaki,H.Takauji,S.Kaneko, 19th International Conference on Pattern recognition, ICPR,Dec 2008
Denighting is the process of enhancing the low contrast night images from the corresponding daytime images of the same scene.
It includes two steps:
(I) Preprocessing in offline
(2) Online process.
To preprocess the image offline, a number of day and night time background images are collected from the static camera and their illuminances are computed using bilateral filter.
During online process, the image is first decoupled into intensity and color . The intensity image is decomposed into reflectance and illumination component. The output of the bilateral filter from the intensity image gives the illumination component. The reflectance component is calculated from the ratio of intensity image and illumination layer.The illuminance of the night time image is then enhanced from the day and night time background illuminances. After enhancing the illumination, the reflectance component is added to get the enhanced intensity, then combined with the color image to get the denighted image.
It includes two steps:
(I) Preprocessing in offline
(2) Online process.
To preprocess the image offline, a number of day and night time background images are collected from the static camera and their illuminances are computed using bilateral filter.
During online process, the image is first decoupled into intensity and color . The intensity image is decomposed into reflectance and illumination component. The output of the bilateral filter from the intensity image gives the illumination component. The reflectance component is calculated from the ratio of intensity image and illumination layer.The illuminance of the night time image is then enhanced from the day and night time background illuminances. After enhancing the illumination, the reflectance component is added to get the enhanced intensity, then combined with the color image to get the denighted image.