In order to simulate the visual effects caused by the change of visual distance, the visual acuity and contrast sensitivity function are researched. The principle of visual acuity and the test method of human contrast sensitivity model are analyzed. Considering of human vision characters, the visual acuity blur algorithm has been presented. It is able to simulate the visual blurred effect, when the visual distance is increased. This algorithm can be used to observe the gray object. Simultaneously the other algorithm is also presented based on contrast sensitivity model, it is capable of simulating the multi-scale characteristics of human visual perception, the visual characteristic of low-pass and band-pass filter, local contrast adaptability and color overlay. When the visual distance is increasing, it is able to simulate the visual blur effects to observe color objects.