forked from luon/wordclock
83 lines
2.1 KiB
Matlab
83 lines
2.1 KiB
Matlab
function lightlevelmapping()
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MINBRIGHTNESS = 3;
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MAXBRIGHTNESS = 10;
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LIGHTSENSOR_BOTTOM = 3;
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LIGHTSENSOR_TOP = 150;
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x = [LIGHTSENSOR_BOTTOM - 10:LIGHTSENSOR_TOP + 10];
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b = zeros(size(9));
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LIGHTSENSOR_ALPHA1 = 0.02;
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LIGHTSENSOR_ALPHA2 = 0.20;
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a = LIGHTSENSOR_ALPHA1 * LIGHTSENSOR_TOP / log(LIGHTSENSOR_ALPHA2 / ...
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LIGHTSENSOR_ALPHA1);
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b = LIGHTSENSOR_ALPHA1 / a;
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c = MINBRIGHTNESS - a;
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y = a * exp(b*x) + c;
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y_ = round(y);
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[x; y_]
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figure
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plot(x, y, x, y_);
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A = axis;
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A(1) = LIGHTSENSOR_BOTTOM - 2;
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A(2) = LIGHTSENSOR_TOP - 2;
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A(3) = MINBRIGHTNESS - 2;
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A(4) = MAXBRIGHTNESS + 2;
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axis(A);
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grid on
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return
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function lightlevelmapping_old()
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MINBRIGHTNESS = 0;
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MAXBRIGHTNESS = 10;
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LIGHTSENSOR_BOTTOM = 0;
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LIGHTSENSOR_TOP = 900;
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l = [LIGHTSENSOR_BOTTOM - 10:LIGHTSENSOR_TOP + 10];
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b = zeros(size(l));
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LIGHTSENSOR_SCALE = 1024;
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LIGHTSENSOR_BASE = 1.35;
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LIGHTSENSOR_BASE = 1.40;
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if (LIGHTSENSOR_BASE <= 1)
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error 'LIGHTSENSOR_BASE must be > 1';
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end
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brightness_per_unit_light = floor(floor( LIGHTSENSOR_SCALE * (MAXBRIGHTNESS - MINBRIGHTNESS)) / ...
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(LIGHTSENSOR_TOP - LIGHTSENSOR_BOTTOM))
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LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - MINBRIGHTNESS) + MINBRIGHTNESS
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% b = floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE ) + MINBRIGHTNESS;
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b1 = (LIGHTSENSOR_BASE.^(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
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LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
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MINBRIGHTNESS) + MINBRIGHTNESS;
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b = floor( (LIGHTSENSOR_BASE.^floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
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LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
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MINBRIGHTNESS)) + MINBRIGHTNESS;
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[brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE; l]
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b1(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
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b1(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;
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b(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
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b(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;
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b2 = round(b1);
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figure
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plot(l, b1, l, b, l, b2)
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A = axis;
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A(3) = -1;
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A(4) = MAXBRIGHTNESS + 1;
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axis(A);
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grid on
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