is there a version of Principle Component Analysis for images?

hello everybody, i want to ask about Principle Component Analysis, a tool used for data analysis

is there a version for PCA that is used for analysis the images?

and i want a source code and some examples for that

thanks for your help

Answer 1

[Sean de Wolski]

doc pca

and

edit pca

[Adam Filion]

And regular pca, which I forgot about...

[Mohamed Moawed]

Page Not Found!!!

[Sean de Wolski]

What version are you using? If you are on a relatively old version, use princomp() as Adam suggested.

doc princomp

Or upgrade to the newest release:

doc pca

[Mohamed Moawed]

yes i used this function: princomp()

but i ask how to use this function on images

thanks for reply

[Sean de Wolski]

Turn the images into column vectors. Spatial location does not matter.

[Mohamed Moawed]

how??? could you please give me some details

thanks

[Sean de Wolski]

x = I(:)

where I is your image.

[Mohamed Moawed]

and after that

y = princomp(x)

[Sean de Wolski]

Essentially. You need to horizontally concatenate all of your images first.

[Mohamed Moawed]

i = imread ('pout.tif'); x = i( : ); y = princomp(x); x = im2double (x); y = princomp(x); imshow (y)

i get no output!!!

what is the wrong here

Answer 2

[Adam Filion]

I don't know much PCA myself, but I know we have some built-in tools in Statistics and Wavelet toolboxes that may be of use:

http://www.mathworks.com/help/stats/princomp.html http://www.mathworks.com/help/wavelet/ug/multiscale-principal-components-analysis.html

There are also a number of entries on the File Exchange for PCA:

http://www.mathworks.com/matlabcentral/fileexchange/index?utf8=%E2%9C%93&term=principal+component+analysis

Answer 3

[Image Analyst]

The most famous application of PCA to images is eigenfaces: http://en.wikipedia.org/wiki/Eigenface You can essentially construct any face image by a weighted sum of eigenface (PCA) images.

[Mohamed Moawed]

what about another images like fMRI cross-sectional images???

[Image Analyst]

Sure, you could do it. Would that be useful to you? Why do you want PCA component images anyway?

[Mohamed Moawed]

i want it to Analyze some fMRI cross-sectional brain images to early diagnosis Alzahimar Disease