I'm trying to make a 3d plot of the pixel intensity in an image, however I cannot seem to make my code work

So I want to be able to import an image (of stars in the sky), and make a 3D plot of the pixel intensity, so that the stars are easily identifiable as "spikes" in the surface.

I've got this code that other's says should work:

J = imread('IMG_1442.jpg');
I = imresize(J,.2)
[x y]=meshgrid(1:size(I,1), 1:size(I,2));
scatter3(x(:),y(:),I(:),15,I(:),'filled');
axis tight; colormap gray

But whenever I run it I get the following error:

Error using scatter3 (line 94)
X, Y and Z must be vectors of the same length.

Error in image_test (line 4)
scatter3(x(:),y(:),I(:),15,I(:),'filled');

(The reason I resize the image is because it is extremely large. I've attached a compressed version of the file so that you can see what I'm working with)

Answer 1

[Walter Roberson]

JPEG images are almost always RGB images, even when they look like black and white. The number of pixel components in an RGB image is 3 times larger than you are expecting. You should convert to grayscale before doing the scatter plot.