saving gray scale images in a 3D array

I want to save 4 gray scale images in a 3D array and use them. I wrote the following code for this purpose but it did not work!

object_dataset1(:,:,1)=rgb2gray(imread('object1_1.jpg'));
object_dataset1(:,:,2)=rgb2gray(imread('object1_2.jpg'));
object_dataset1(:,:,3)=rgb2gray(imread('object1_3.jpg'));
object_dataset1(:,:,4)=rgb2gray(imread('object1_4.jpg'));

when I use the imshow function to show one of the images it show a white surface!!

for example : imshow(object_dataset1(:,:,2));

Answer 1

[Cris LaPierre]

Not sure. It works for me.

Check that all your images have the exact same dimensions.

Also, sanity check your code. What happens when you run this?

img = imread('object1_1.jpg')
imshow(img)

img_gr = rgb2gray(imread('object1_1.jpg'))
figure
imshow(img_gr)

object_dataset1(:,:,1)=rgb2gray(imread('object1_1.jpg'));
object_dataset1(:,:,2)=rgb2gray(imread('object1_1.jpg'));
object_dataset1(:,:,3)=rgb2gray(imread('object1_1.jpg'));
object_dataset1(:,:,4)=rgb2gray(imread('object1_1.jpg'));
figure
imshow(object_dataset1(:,:,1))

Note that this actual line of code won't run:

for example : imshow(object_dataset1(:,:,2))

I assume that is just a copy/paste error since otherwise you'd be reporting an error message instead of a white image.