One goal of projector-camera system is let human finger be used like a mouse to click and drag objects in the projected content. It requires segmentation of the human palm and fingers in the image data captured by the camera, which is a challenging task in the presence of the incessant variation of the projected video content and the shadow cast by the palm and fingers. We describe a coarse-to-fine hand segmentation method for projector-camera system. After rough segmentation by contrast saliency detection and mean shift-based discontinuity-preserved smoothing, the refined result is confirmed through confidence evaluation. Extensive experimental results are shown to illustrate the accuracy and efficiency of the approach.