MATLAB: How to find the variance of an image

Image Processing Toolbox

i try to find the variance by var function but it shoew the error. I = imread('eight.tif'); var(I)

Best Answer

var requires a double or single argument. This will work:

img = double(imread('eight.tif'));
v = var(img);

But note that will give a vector, with one value for the variance of each column of the image. To get the variance of all the pixels in the image, you'll need

v = var(img(:));

Related Solutions

MATLAB: Lighthouse.jpg imread into matrix and calculate mean and std? – Homework

The standard deviation of the standard deviation of the columns is not the standard deviation of the entire image! It's not like the max, min, and mean functions. Try a simple example and you'll see. Just do

imsr = std(imr(:));

to get the standard deviation of an entire array (a single color channel). imr(:) converts the 2D array into a 1D array.

MATLAB: How to create an image by replacing each pixel with mean RGB value.

Specify the dimension to the mean function. It will create a grayscale image

img = im2double(imread('peacock.jpg'));
img_mean = mean(img, 3);
 
fig = figure();
subplot(1, 2, 1);
imshow(img);
subplot(1, 2, 2);
imshow(img_mean);

Best Answer

Related Solutions

MATLAB: Lighthouse.jpg imread into matrix and calculate mean and std? – Homework

MATLAB: How to create an image by replacing each pixel with mean RGB value.

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