MATLAB: Size function in MATLAB

imageImage Processing Toolboxsize;

As we write size(img),it returns 3 values. I need to know what does the last value tells us? My result is 240 320 5. What does 5 tell?

Best Answer

It has 5 color channels. You have a multi-spectral image.

[rows columns numberOfColorChannels] = size(yourImageArray);

numberOfColorChannels = 1 for a gray scale image, =3 for an RGB image or volumetric gray scale image, and >3 for multi-spectral images or higher dimensional arrays.

Related Solutions

MATLAB: Are all grayscale images of the size 256*256. Please clarify

The size of your image is 289 x 318, as returned by the size command. Why do you think that the size is 256*256? A grayscale image can be of any size, only some of them are of size 256 x 256. The range of values are from 0 to 255, for a uint8 type image, so each pixel can take one from 256 different values. But that's the value of a pixel and has nothing to do with the size.

MATLAB: How to code image types

Try this:

grayImage = imread(fullFileName);
% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
	% It's not really gray scale like we expected - it's color.
	% Use weighted sum of ALL channels to create a gray scale image.
% 	grayImage = rgb2gray(grayImage);
	% ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
	% which in a typical snapshot will be the least noisy channel.
	grayImage = grayImage(:, :, 1); % Take red channel.
end
if max(grayImage(:)) == 1 && length(unique(grayImage(:))) == 2
    % It's binary because it has only two values: 0 and 1
else
    % It's grayscale
end

You can also use isa(grayImage, 'logical') or similar to identify what class it is.

Best Answer

Related Solutions

MATLAB: Are all grayscale images of the size 256*256. Please clarify

MATLAB: How to code image types

Related Question