Method for generating marks on the presentation screen using virtual pen

The present invention relates to a method for generating marks on the presentation screen using virtual pen, which employs the image capturing device to capture the entire presentation screen outputted from the image output device and conducts the coordinate definition on the screen; then, when the user uses the virtual pen to generate light spot, line or pattern on the presentation screen, the image capturing device will capture the presentation screen, and detect the light spots thereon or the tracks generated thereby for the coordinate correction operation; and, generating the marking lines or patterns by the image output device at the same position based on the light spots or the generated tracks. Thus, the user can conveniently generate fixed emphasis marks on the presentation screen to solve the defect that it could only be operated on the computer in the past.