I have calculate the color histogram values of 30 images in a database. Now i want to calculate the local color histogram values of images dividing the image into 4 equal parts.How i proceed using the following code?

srcFiles=dir('fruits\*.jpg');
for i= 1:length(srcFiles)
  disp(i);
  Filename=strcat('fruits\',srcFiles(i).name);
  I=imread(Filename);
  %imresize(I, [177 284])
  imshow(I),figure
[index, map]=rgb2ind(I,65300);
pixels= prod(size(index));
hsv=rgb2hsv(map);
h = hsv(:,1);
s = hsv(:,2);
v = hsv(:,3);
darks = find(v <.2)';
lights = find(s < .05 & v  > .85)';
h([darks lights])= -1;
disp(length(darks))
black = length(darks)/pixels;
white = length(lights)/pixels;
red = length(find((h >.9167 | h <=.083) & h~=-1))/pixels;
yellow=length(find(h >.083 & h<=.25))/pixels;
green=length(find(h > .25 & h<= .4167))/pixels;
cyan= length(find(h > .4167 & h<= .5833))/pixels;
blue=length(find(h > .5833 & h <= .75))/pixels;
magenta=length(find(h > .75 & h <= .9167))/pixels;
disp('Red=')
disp(red)
disp('Blue=')
disp(blue)
a(i,1)=red
a(i,2)=green
a(i,3)=blue
a(i,4)=yellow
a(i,5)=cyan
a(i,6)=magenta
a(i,7)=black
a(i,8)=white
end
dlmwrite('frs.mat',a)
b=dlmread('frs.mat')
%c={'red','green','blue','yellow','cyan','magenta','black','white'}
%f={c;a}
%snames = nominal({'10.jpg';'11.jpg';'12.jpg';'13.jpg';'14.jpg';'15.jpg';'16.jpg';'17.jpg';'18.jpg';'19.jpg';'20.jpg';'21.jpg';'22.jpg';'23.jpg';'24.jpg';'25.jpg';'26.jpg';'27.jpg';'28.jpg';'29.jpg';'30.jpg';'31.jpg';'32.jpg';'33.jpg';'34.jpg'});
%f = dataset({snames,'images'},{[a(i,1);a(i,2);a(i,3);a(i,4);a(i,5);a(i,6);a(i,7);a(i,8)],'f'})
hold on
fill([0 0 1 1], [0 red red 0], 'r')
fill([1 1 2 2],[0 yellow yellow 0], 'y')
fill([2 2 3 3],[0 green green 0], 'g')
fill([3 3 4 4],[0 cyan cyan 0], 'c')
fill([4 4 5 5],[0 blue blue 0], 'b')
fill([5 5 6 6],[0 magenta magenta 0], 'm')
fill([6 6 7 7],[0 white white 0], 'w')
fill([7 7 8 8],[0 black black 0], 'k')
axis([0 8 0 1])
%fr=strcat('features_',Filename,'.mat');

[Anamika baruah]

please give coment on my answer

Answer 1

[Image Analyst]

Divide the image up into 4 individual color channels:

% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);

Then see David's answer for dividing the image into 4 quadrants: http://www.mathworks.com/matlabcentral/answers/136640#answer_141764 and call imhist() for each quadrant of each color channel.

[Anamika baruah]

there are only three channels in a color image

[Image Analyst]

Yes....so?