2D Image FFT (2D) — Frequency-Domain Image Filtering

Test pattern Filter type Cutoff radius 16 Draw on canvas (adds to image) Image size

64 × 64

128 × 128

Resolution64 × 64

Cutoff freq16 cyc/img

Energy kept—

Compute time—

A real 2D FFT (row-column decomposition: a 1D radix-2 Cooley–Tukey FFT run on every row, then every column) turns the image into a complex frequency spectrum. After an fftshift the centre holds the DC (average-brightness) term; a low-pass mask keeps only a disc around the centre (blur), a high-pass mask removes it (edges only). The masked spectrum is inverse-FFT'd back to a real image. Enable "Draw on canvas" and paint on the spatial-image panel to add your own strokes to the source before it's transformed.

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