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what does 4D of an image indicates?

Asked by Sivakumaran Chandrasekaran on 12 Mar 2013

2D means, row and columns of an image.. 3D means.. row,column,RGB... in 4D, what are the dimensions it indicates?

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Sivakumaran Chandrasekaran

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2 Answers

Answer by Image Analyst on 12 Mar 2013
Accepted answer

If you have multiple multispectral images then it's a 4D image, for example a stack of color confocal microscopy images where each slice/layer is a 3 color (RGB) image. Or the Visible Human though they may store their data in some special format on disk.

Another example would be a color video where each color frame is a 3D image but you have multiple frames taken at different times. So the 4th dimension is time.

1 Comment

thanks image analyst and thanks walter.. you have multiple frames taken at different times. So the 4th dimension is time. this will match my requirement.

Image Analyst
Answer by Jan Simon on 12 Mar 2013

It depends. The 4th component could mean an alpha channel, see "RGBA". Or the image is not stored in RGB colors, but in the CMYK color model. Or you have 4 different layers of grayscale images, e.g. stored in a TIFF file. Or it is any other 4 channel image taken by a camera which records 4 different wavelengths, perhaps green and 3 different infra-read-channels.

3 Comments

Hi Jan, your reply suits my requirement. i used video and image processing blockset.(simulink). the output was stored in workspace in 4D format. I am unable to open that file, because there was more number of pixels in it.

Walter Roberson on 12 Mar 2013

The 4th dimension is probably for an image sequence. I(:,:,:,J) being for the J'th image.

Image Analyst on 12 Mar 2013

A multispectral image is a 3D image no matter how many spectral channels it has. If you have multiple multispectral images then it's a 4D image, for example a stack of color confocal microscopy images where each slice/layer is a 3 color (RGB) image.

Jan Simon

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