function lightlevelmapping()
MINBRIGHTNESS = 3;
MAXBRIGHTNESS = 10;

LIGHTSENSOR_BOTTOM = 3;
LIGHTSENSOR_TOP = 150;

x = [LIGHTSENSOR_BOTTOM - 10:LIGHTSENSOR_TOP + 10];
b = zeros(size(9));

LIGHTSENSOR_ALPHA1 = 0.02;
LIGHTSENSOR_ALPHA2 = 0.20;

a = LIGHTSENSOR_ALPHA1 * LIGHTSENSOR_TOP / log(LIGHTSENSOR_ALPHA2 / ...
	LIGHTSENSOR_ALPHA1);
b = LIGHTSENSOR_ALPHA1 / a;
c = MINBRIGHTNESS - a;

y = a * exp(b*x) + c;
y_ = round(y);

[x; y_]

figure
plot(x, y, x, y_);
A = axis;
A(1) = LIGHTSENSOR_BOTTOM - 2;
A(2) = LIGHTSENSOR_TOP - 2;
A(3) = MINBRIGHTNESS - 2;
A(4) = MAXBRIGHTNESS + 2;
axis(A);
grid on

return

function lightlevelmapping_old()
MINBRIGHTNESS = 0;
MAXBRIGHTNESS = 10;

LIGHTSENSOR_BOTTOM = 0;
LIGHTSENSOR_TOP = 900;

l = [LIGHTSENSOR_BOTTOM - 10:LIGHTSENSOR_TOP + 10];
b = zeros(size(l));

LIGHTSENSOR_SCALE = 1024;
LIGHTSENSOR_BASE = 1.35;
LIGHTSENSOR_BASE = 1.40;

if (LIGHTSENSOR_BASE <= 1)
	error 'LIGHTSENSOR_BASE must be > 1';
end

brightness_per_unit_light = floor(floor( LIGHTSENSOR_SCALE * (MAXBRIGHTNESS - MINBRIGHTNESS)) / ...
	(LIGHTSENSOR_TOP - LIGHTSENSOR_BOTTOM))

LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - MINBRIGHTNESS) + MINBRIGHTNESS

% b = floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE ) + MINBRIGHTNESS;
b1 =  (LIGHTSENSOR_BASE.^(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
	LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
	MINBRIGHTNESS) + MINBRIGHTNESS; 
b = floor( (LIGHTSENSOR_BASE.^floor(brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / ...
	LIGHTSENSOR_SCALE)) / LIGHTSENSOR_BASE^(MAXBRIGHTNESS - MINBRIGHTNESS) * (MAXBRIGHTNESS - ...
	MINBRIGHTNESS)) + MINBRIGHTNESS;

[brightness_per_unit_light * (l - LIGHTSENSOR_BOTTOM) / LIGHTSENSOR_SCALE; l]

b1(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
b1(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;
b(l <= LIGHTSENSOR_BOTTOM) = MINBRIGHTNESS;
b(l >= LIGHTSENSOR_TOP) = MAXBRIGHTNESS;

b2 = round(b1);

figure
plot(l, b1, l, b, l, b2)
A = axis;
A(3) = -1;
A(4) = MAXBRIGHTNESS + 1;
axis(A);
grid on