Improving Image Contrast: Fourier Filtering Techniques

This lecture discusses methods for improving image contrast using optical techniques, specifically through Fourier filtering in a 4F optical setup. The instructor begins by explaining the concept of contrast improvement, emphasizing the importance of enhancing edges in images. The 4F setup is introduced, where the object is placed at a specific distance from the objective lens, allowing for the introduction of filters in the Fourier plane. The lecture illustrates how a filter can block low-frequency components while allowing high-frequency components to pass, resulting in a clearer image with improved contrast. The instructor also explores the effects of applying a linear gradient filter in the Fourier plane, explaining how it alters the final image. Additionally, the lecture covers more complex filters that involve intensity and phase variations, demonstrating their impact on images containing text. Overall, the lecture provides a comprehensive overview of Fourier optics and its applications in enhancing image quality through contrast improvement.