You can use this code to generate the color rows:
clear all;
figure
for bits = 1:1:8
Color=2^bits; %Number of colors level
intervalo = 1/(Color-1); %intervales to each color
C = zeros(Color,1,3); %To change rows by columns change this line zeros(1,Color,3)
s = 1:-intervalo:0;
C(:,:,1) = s'; % Red
C(:,:,2) = s'; % Green
C(:,:,3) = s'; % Blue
subplot(3,3,bits);
image(C); % C is mean of three channel (RGB)
numeroBits = num2str(bits);
title({'\fontsize{12} Número de bits:' numeroBits});
axis off;
end
To resize you can use imresize();
