The Fourier Transform is a powerful tool allowing us to move back and forth between the spatial and frequency domains. This applet helps students feel comfortable, 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.
