Matlab size of image

Question

I am trying to find the size of an image I have loaded into matlab.

image=imread('text.jpg');
[x,y]=size(image);

This return the error:

Indexing cannot yield multiple results.

Does imread not read the image into a 2d array, which should therefore have two sizes?

Your code looks OK to me. Have you tried using, say, imfinfo to see what's in the file ? — High Performance Mark, Mar 04 '12 at 13:12

score 18 · Answer 1 · answered May 14 '14 at 12:50

For those looking to find the size of an image in matlab, don't use:

[height, width] = size(image);

This is because imread stores the RGB values separately (for colour images), resulting in a three dimensional matrix.

For example, if you loaded a 500p high, 200p wide colour image, this would result in a 500x200x3 matrix.

Calling size() in this way would result in the dimensionality being 'rolled up', and would report the height to be 500, but the width to be 600 (200 * 3).

Instead, using:

[height, width, dim] = size(image);

would return correct values of 500, 200, 3.

how would i find it out without the RGB values ? i only need the pixels and not the colour. — Oscar Dolloway, Apr 22 '18 at 15:48

3lectrologos · Accepted Answer · 2012-03-04T13:14:33.170

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Is it possible that you have defined a variable named size before this code?

edited Mar 04 '12 at 13:14

answered Mar 04 '12 at 13:01

3lectrologos

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Yes, that was it! Sorry for not spotting the obvious mistake! Thanks. – Joseph Mar 04 '12 at 13:19

score 3 · Answer 3 · edited Apr 07 '16 at 02:46

3

You must use [height, width, colour_planes] = size(image); because images have 3 dimensions. The third dimension is the number of colour planes. If you don't need this value, you can substitute ~ to ignore it.

edited Apr 07 '16 at 02:46

Alexander

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answered Nov 14 '12 at 03:35

KyungHoon Kim

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what is the 3rd dimension? – scord Sep 19 '13 at 18:51
The colour. The 1st dimension is the red values, 2nd is greens, and 3rd is blues – Alexander Feb 04 '16 at 19:57

score 1 · Answer 4 · edited May 30 '13 at 06:33

1

Just use this whos and press enter.

image=imread('text.jpg');
whos

edited May 30 '13 at 06:33

Nazik

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answered May 30 '13 at 05:56

Eng. Marthed

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score 1 · Answer 5 · answered Jun 10 '14 at 03:23

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[x,y,z]=size(image); is the correct one. x and y will give length and breadth of the image and z specifies color.

Digital image consists of RGB so z will be 3.

answered Jun 10 '14 at 03:23

Sndn

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score -3 · Answer 6 · edited Apr 05 '13 at 11:32

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You can try this:

image=imread('text.jpg');
[x y]=size(image);

edited Apr 05 '13 at 11:32

Seth Malaki

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answered Apr 05 '13 at 11:09

Fooz

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Matlab size of image

6 Answers6