The Fourier Transform is a powerful tool allowing us to move back and forth between the spatial and frequency domains. Many of our explanations of key aspects of signal processing rely on an understanding of how and why a certain operation is performed in one domain or another. This applet helps students feel comfortable with these explanations, helping to build a strong intuitive grasp of how signals in one domain correspond to signals in the other.
Students can load scanlines from common image patterns and see that scanline's Fourier Transform in real-time. For example, they can load the scanline of a standard test image to note how most of the energy is concentrated at low frequencies -- a key to why low-pass filtering doesn't render an image unintelligible.
Students trying to understand how signals in the spatial and frequency domains relate to each other.
Load an image by selecting its name in the drop-down menu in the upper-left portion of the screen. Click and drag on the image to move the scanline and observe the graphs below. The top graph corresponds to the scanline in the spatial domain. The bottom graph corresponds to the scanline in the frequency domain.