Comments on: Eigenfaces Tutorial

By: Manfredas Zabarauskas

Manfredas Zabarauskas — Fri, 21 Oct 2011 13:55:00 +0000

Thanks Jason, it is indeed supposed to be N*N x R. I've fixed it in the tutorial above, very well spotted!

Jason :
One question though, shouldn't the U matrix be size N*N x R and not NxR?

By: Jason

Jason — Thu, 08 Sep 2011 17:34:51 +0000

Thank you very much for this post, it was hands down the best around. I've successfully implemented this method. One question though, shouldn't the U matrix be size N*N x R and not NxR? Or did I miss something?

By: Usman Khalid

Usman Khalid — Thu, 16 Jun 2011 04:16:14 +0000

Thanks Bro this is greatest tutorial. Every thing is explained very beautifully and completely.

Thanks Allot.

By: Manfredas Zabarauskas

Manfredas Zabarauskas — Sat, 25 Dec 2010 00:22:37 +0000

Hi Tom, You should make sure that the length of the each eigenvector (the square root of the sum of its squared components) is equal to one. See this link if you need more details: http://en.wikipedia.org/wiki/Unit_vector Hope this helps!

Tom Price :
Hi,

Brilliant tutorial, one question however…

The values I get for my eigenVectors are floats (some are negative values), when you say normalized..what do you mean? Do I take the absolute value of the numbers?

Thanks for your help

Tom

By: Tom Price

Tom Price — Wed, 22 Dec 2010 14:09:36 +0000

Hi,

Brilliant tutorial, one question however...

The values I get for my eigenVectors are floats (some are negative values), when you say normalized..what do you mean? Do I take the absolute value of the numbers?

Thanks for your help

Tom

By: Manfredas Zabarauskas

Manfredas Zabarauskas — Thu, 25 Nov 2010 22:27:07 +0000

Hi Yuya, No, the eigenvectors in general will not be in the range [0..255]. You should scale them to that range if you want to render them on the screen, however, for the face classification step make sure that your eigenvectors are normalized.

Yuya Suzuki :
It is great Tutorial.
but i have 1 question.
After calculate eigenvectors,eigenvectors is already become [0.255]?
or do scale [0.255]?

By: Manfredas Zabarauskas

Manfredas Zabarauskas — Thu, 25 Nov 2010 22:21:17 +0000

Hi Viduruvan, technically there is no reason why you shouldn't try coloured encoding and see if you obtain a better recognition rate. It might be the case that digital noise from the webcam will introduce a lot of variance in 8-bit color mode, but... give it a shot!

Viduruvan :
Dear ,
Good Artical.

Actually why do we need a grayscale face images ?

what is the diffent between grayscale and ” normalized (so that every pixel has a value between 0 and 255 (i.e. one byte per pixel encoding) )”

By: Yuya Suzuki

Yuya Suzuki — Wed, 24 Nov 2010 05:54:12 +0000

It is great Tutorial.
but i have 1 question.
After calculate eigenvectors,eigenvectors is already become [0.255]?
or do scale [0.255]?

By: Viduruvan

Viduruvan — Mon, 07 Jun 2010 14:28:46 +0000

Dear ,
Good Artical.

Actually why do we need a grayscale face images ?

what is the diffent between grayscale and " normalized (so that every pixel has a value between 0 and 255 (i.e. one byte per pixel encoding) )"

By: Manfredas Zabarauskas

Manfredas Zabarauskas — Tue, 12 Jan 2010 16:57:13 +0000

Thanks, Midorj, glad to hear that!

Midorj :
Great, thank so much. Your tutorial helps me a lot. very much appreciate!!