Systems and methods are provided for identifying dark areas in images captured by encapsulated cameras or endoscopes and enhancing the visibility of the dark area using intensity stretch. For capsule or endoscope images, there are often some dark areas caused by inadequate lighting. The poor visibility of detailed features in the dark area may reduce the detection rate of anomaly. The present invention calls for a method to detect the dark area based on contour. The intensities inside and outside the dark area are evaluated and are used to generate intensity transformation to stretch intensity in the dark area while minimizing the impact on the image quality outside the dark area.