Convert images to matrix

21 sec read

Quite often you need to convert an image (or multiple images) to a MatLab matrix for further analysis and visualization (e.g. extracting time series, multivariate pattern analysis, etc). SPM provides handy functions for this:

P = spm_select; % select 1 or more images
V = spm_vol(P);
M = spm_read_vols(V);

The dimension of M is 3D or 4D depending on how many images you selected. The 1st 3 dimensions are spatial and the last one is temporal.

If you want to save a matrix to a image file, use

V.fname = 'b.img';%
spm_write_vol(V, M);

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3 Replies to “Convert images to matrix”

  1. sir,
    i need to generate .mat file for ORL database(say). how to do it?also can i use the same .mat file in regression/classification?how to split database into predictor and response arrays (X & Y) for regression/classification.
    please provide suitable matlab functions.
    thank you

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