T1 · Motion in natural content

The color image remains stationary. A horizontal carrier modulates each linear RGB channel multiplicatively. The direction question concerns the moving modulation, not displacement of the photographed scene.

N = 0.62 · linearRGB(input)
M(x, y, t) = N(x, y) · [1 + m W(x, y) cos(2π f x / 448 − s 2π h t + φ)]

Stripe strength is the modulation depth m, a dimensionless parameter in the RGB multiplier. Where W = 1, that multiplier ranges from 1 − m to 1 + m. It is not the global contrast of the natural image.

W is one inside radius 192 px and falls to zero with a 32 px cosine edge, ending at radius 224 px. No Gaussian envelope is used. Left and right classical controls share the same pedestal and amplitude, fitted to the direction pair’s pooled mean and modulation RMS inside the aperture. The fit uses the actual 8-bit reference pixels; measured residuals are listed above. Natural texture RMS is not matched. The reference buffer is 8-bit sRGB with dithering disabled.

The reference timeline advances in 1/120 s steps. 120 reference frames/s is neither a claim about browser refresh nor a measured model input rate. All visible panels use the same clock. Each exposure returns to its unmodulated background at its own endpoint. Pause and seeking are for frame inspection. The rightmost Earlier classic is the preserved 7 Oct sample (512², 400 px aperture, 8 cycles/aperture, aperture RMS 0.09, 24 fps, 72 frames, LEFT). Its player is independent: current parameters do not change this historical clip. These new samples have no model performance curves.

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