In recent years, how to quantify visualizations of an object and surface displayed in 3D space is now more prominent with a rapid increase in the demand for three-dimensional (3D) content. In order to measure the content information in terms of human visual perception, it is necessary to quantify the visual information in accordance with the human visual system. In this paper, we propose a framework for expressing visual information in bits termed visual entropy based on information theory. The visual entropy of 2D content (2DVE) is composed of texture entropy on the 2D surface and depth entropy based on the monocular cue. In addition to 2DVE, the visual entropy of 3D content (3DVE) includes the depth entropy based on the binocular cue. A series of simulations are conducted to demonstrate the effectiveness of visual entropy, including a performance trade-off between 2D and 3D visualizations measured according to the bitrate.