Abstract
Many investigators have studied on form perception. The problems mentioned here were one of those specified under the broader area of form perception. A considerable practical significance in form perception concerns a perceptual process of target; visibility, legibility and readability.
Most types of visual signs present to an operator a considerable amount of extraneous information. His task frequently requires him to filter relevant from irrelevant stimulus before deciding on the appropriate response. In this case, the operator must speedily and accurately recognize relevant stimulus. So, some important parameters perception of target were reviewed. Moreover, as an example of the application traffic road sign was studied
