Abstract: A computing device-implemented method and the computing device thereof are provided. A center area and an outer area of the picture displayed on the touch-sensitive screen are defined. An image processing operation, such as zooming in, zooming out, or movement on the picture displayed on the touch-sensitive screen is performed based on the relationship of the initial location and the orientation of the sliding motion, and the center area and the outer area of the picture. Therefore, basic picture operations can be carried out by a single finger possibly while holding the device with the same palm to improve usability and to user safety.