Histogram of an image - matlab

Question

I need to take histogram of each splited image and i want to calculate mean and variance of the splited image. here i am getting an error while i calculating the mean value..... please guide me
[h w c] = size(x);
numSplits = 3; %
sw = floor(w/numSplits); %
widths = repmat(sw, 1, numSplits-1);
widths(numSplits) = w - sum(widths);
splits = mat2cell(x, h, widths, c);
% show the splits
for ii=1:numSplits
subplot(1,numSplits,ii);
imshow(splits{ii});
g(ii)=(splits{ii});
figure, imhist(g(ii));
end
%mean
im1=g(ii);
su=mean2(im1);
mean=ceil(su);
disp('mean Value');
disp(mean)
%variance
sv=double(im1);
v = var(sv);
disp(v)
i need to get the histograms of each seperate images and i need to calculate the mean for that splitted images

Answer 1

I assume that x is the image you want to split and analyze and that it is the image you have linked:
First, I load the image (you have already done this, I guess, so you do not need to copy this):
x = imread('https://i.stack.imgur.com/4PAaI.png');
The following code solves your coding errors:
[h, w, c] = size(x);
numSplits = 3; %
sw = floor(w/numSplits); %
widths = repmat(sw, 1, numSplits-1);
widths(numSplits) = w - sum(widths);
splits = mat2cell(x, h, widths, c);
results = repmat(struct('mean',[], 'variance',[]),numSplits, 1);
% show and analyze the splits
for ii=1:numSplits
subplot(2,numSplits,ii);
imshow(splits{ii});
subplot(2,numSplits, ii+numSplits);
imhist(splits{ii});
results(ii).mean = mean2(splits{ii});
results(ii).variance = (std2(splits{ii})).^2;
end
The mean and variance are stored in results:
>> results(1)
ans =
struct with fields:
mean: 118.0233
variance: 1.3693e+03
>> results(2)
ans =
struct with fields:
mean: 126.1719
variance: 1.9608e+03
>> results(3)
ans =
struct with fields:
mean: 121.9004
variance: 958.3740
However, please double check that you really want to compute the stats for the combined color channels of the images and not only for, for eample, the red one.