Colour quantization, uniform quantization

Hi there, I'm working on a project on colour quantization and I'm a little lost with matlab (complete beginner). The method of quantization I'm working on is uniform quantization which splits the red and green axis into 8 segments and the blue axis into 4 giving 256 regions. Then finds the average colour in each region. I'm wondering how I would go about this my code so far for this:

image = imread(ImageName);

red = loadedImg(:,:,1);
green = loadedImg(:,:,2);
blue = loadedImg(:,:,3);

I honestly have no idea as I'm new to matlab! Thanks in advance!

Answer 1

[Image Analyst]

Don't call your image "image". Call it loadedImage or something because image() is the name of a built-in function. So then just do a for loop to get the 3D gamut. Attached is an example.

[Debs Bradley]

Sorry but I don't quite understand what 3D gamut does? Would you mind explaining in terms of the example you provided?

Answer 2

[Yashwanth]

% Uniform Quantization of Piecewise Signal

t1 = -1:0.01:0;

t2 = 0.01:0.01:1;

x1 = t1 + 1;

x2 = t2 - 1;

t = [t1 t2];

x = [x1 x2];

figure;

plot(t,x);

title("Original Signal");

xlabel("time");

ylabel("amplitude");

grid on;

x_max = max(x);

x_min = min(x);

N = 8;

delta = (x_max - x_min)/N;

R = x_min:delta:x_max;

x_h = zeros(1,length(x));

for i = 1:length(x)

for j = 1:(length(R)-1)

if x(i) >= R(j) && x(i) <= R(j+1)

x_h(i) = R(j) + (delta/2);

end

end

end

figure;

stem(t,x_h);

title("Quantization Level");

xlabel("time");

ylabel("level");

grid on;

figure;

stem(x,x_h);

title("Transfer Characteristics");

xlabel("Input Signal");

ylabel("Quantized Signal");

grid on;

Answer 3

[Yashwanth]

x = random('norm',2,sqrt(5),1,10000);

subplot(3,1,1)

stem(x)

title("Gaussian signal")

xlabel("time")

ylabel("amplitude")

N = 8;

[R,C] = lloyds(x,N);

[index,q] = quantiz(x,R,C);

subplot(3,1,2)

stem(q)

title("Quantization Level")

xlabel("Number of Random Variables")

ylabel("q")

subplot(3,1,3)

stem(x,q)

title("Transfer Characteristics")

xlabel("x")

ylabel("q")