| Popis: |
MTF (Modular Transfer Function) is used as a metric for the sharpness of the images displayed on a monitor. However, MTF is often only measured in one dimension (usually horizontally or vertically). The goal of this work is to provide a methodology that allows measuring the MTF of a display correctly in 2D. Existing methodologies are analyzed to determine if they are satisfactory. We concluded that all of the currently used methodologies have shortcomings. To overcome the limitations of the existing technologies, a new methodology is introduced, the Pixel Spread Function. In this methodology, an impulse to the display is approximated by a single lit pixel, on a uniform background. The measurements are performed at a very close distance, to limit the degradations introduced by the measurement system. By applying signal processing, the 2D MTF has been obtained for this methodology. After averaging the results for multiple images and pixel positions and removing the camera degradation, the methodology proved to be reproducible and easy to perform. To validate the proposed methodology, a mathematical model has been created that allows simulating the MTF. Since the geometrical structure of the pixel has the largest impact on the obtained result, the model is based on it. Other degradations in the system (aberrations, diffraction...) are approximated by an additional blurring step. The theoretical and experimental results were compared, and it was concluded that the methodology is valid. |
