Systems and methods are provided for environment change sensing corresponding to the capsule camera entering the colon from the small intestine. In the environment change sensing mode, the capsule camera is operated in a very low power mode by configuring the image sensor to use a small region of interest or a high sub-sampling ratio. Image data is processed to estimate the light level. The variation of light level is used to detect environment change corresponding to entering the colon from the small intestine. Alternatively, the motion metric for a current frame and a reference frame is evaluated. The characteristic of the motion metric is extracted and used to detect environment change. In another configuration, the system determines environment change based on a combination of the variation of light intensity and the characteristic of the motion metric. Upon the detection of capsule camera entrance into the colon from the small intestine, control signals are provided to the image sensor and the light source.