42 lines
1.1 KiB
Lua
42 lines
1.1 KiB
Lua
-- sgm_uniform.lua: SGM Uniform (Karras) — uniform in σ^(1/ρ) space
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scheduler = {
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name = "sgm_uniform",
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display = "SGM-Uniform (Karras)",
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description = "Karras σ-ramp (ρ=7), front-loads structural steps",
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}
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function schedule(output, num_steps, shift)
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local t_max = 0.999
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local t_min = 0.001
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local sigma_max = t_max / (1 - t_max)
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local sigma_min = t_min / (1 - t_min)
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local rho = 7.0
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local inv_rho = 1.0 / rho
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local s_max = sigma_max ^ inv_rho
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local s_min = sigma_min ^ inv_rho
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for i = 0, num_steps - 1 do
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local frac = i / num_steps
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local sigma = (s_max + frac * (s_min - s_max)) ^ rho
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output[i] = sigma / (1 + sigma)
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end
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clamp(output, num_steps)
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apply_shift(output, num_steps, shift)
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end
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function apply_shift(ts, n, shift)
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if shift == 1.0 then return end
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for i = 0, n - 1 do
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local t = ts[i]; ts[i] = shift * t / (1.0 + (shift - 1.0) * t)
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end
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end
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function clamp(ts, n)
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for i = 0, n - 1 do
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if ts[i] < 1e-6 then ts[i] = 1e-6 end
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if ts[i] > 1.0 then ts[i] = 1.0 end
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end
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end
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