why this gives me "Index exceeds matrix dimensions?" can any one help me. Thanks in advance

figure
img = imshow(stretched_CIR);
title('CIR after Decorrelation Stretch');
h = imfreehand;
m = createMask(h, img);
delete(h)
% Extract individual color channels
r = img(:,:,1);
g = img(:,:,2);
b = img(:,:,3);

%Now I evaluate for RGB color channels;

>> r = img(:,:,1); 
%works but
>> g = img(:,:,2);
Index exceeds matrix dimensions.

%why?

Answer 1

[Matthew Eicholtz]

Are you sure the image is RGB instead of grayscale? As the error suggests, the variable img must not have a 2 layer in the 3rd dimension.

Answer 2

[Surya Gnyawali]

The image is attached. Please advise

Answer 3

[Guillaume]

The problem is with

img = imshow('...')

As per the documentation of imshow, its return value is a handle to a graphics object, not an image. You need to load the image properly with imread:

img = imread(stretched_CIR);
%and if you want to see the image
imshow(img);