## array size notation

on 24 Mar 2012

### Jan Simon (view profile)

Hi,

I have a doubt in working with Images. An image is represented in MATLAB in the form of row multiplied with columns.

3D image has been represented as for e.g., 256 * 208 *2...

In the above example, 256 indicates rows. 208 indicates columns..

Could you tell me 2 indicates what factor exactly.

Could you explain the same concept for 4D images also.

Thanks & Regards,

Siva

vlsiva@yahoo.co.in

9003241032

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### Jan Simon (view profile)

on 24 Mar 2012

The rows and columns are not multiplied. "256 * 208 * 2" means, that the array has the dimensions [256, 208, 2]. The trailing 2 could mean, that each pixel of a 2D plane has 2 color components, e.g. hue and saturation or red and blue. Or the first component can be the Z-value, while the second one is the grey level.

There is no standard definition for 4D images (as there is no for 3D images). It could be a movie, when the 4th component is the time and the first 3 components are RGB images.

Is it clearer now? The numbers are not factors, but the dimension of a kind of table.

### Sivakumaran Chandrasekaran (view profile)

on 24 Mar 2012

Hi Jan, Thanks for your reply. consider the following. You are standing. a train is running on your background. Now i am capturing this situation.

Whether the obtained image is a 4D image.

Regards. Siva

Jan Simon

### Jan Simon (view profile)

on 27 Mar 2012

I do not understand the statement. Is this a question? Do you want to know, if this situation can be represented as 4D array? If so, it depends on what you call "capturing". Taking a movie on tape means discrete 5D data usually: 2D matrix of [1x3] RGB value, one for each frame, plus sound. On the other hand these data are stored sequentially on the tape, so you actually have an 1D data stream...

Sivakumaran Chandrasekaran

### Sivakumaran Chandrasekaran (view profile)

on 28 Mar 2012

capturing means, just a still image. not a video

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