Re: Errata for Gonzalez/Wintz?

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#561

From: James Phillip ANDREW
Date: Wed, 07 Oct 1992 22:53

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cjwein@watcgl.uwaterloo.ca (Chris J. Wein) writes:

>I knew about 2 seconds after I posted that article about G and W that
>I should have mentioned the error so here goes...

>In the section about the discrete cosine transform they define
>the 1D DCT as ...cos((2x+1)u*pi/N)...  When they combine two 1D
>DCT's to form the 2D transform they pull out the 1/N as the argument
>to the cos to form ... (1/N^2)cos((2x+1)u*pi)*cos((2y+1)v*pi) which
>is essentially saying that cos(x/n)*cos(y/n) = (1/n^2)cos(x)cos(y).

Errata:

Shouldn't the 1D kernel (and hence 2D) be cos((2x+1)u*pi/2N) ?

James Andrew
Wollongong

>It is corrected in the Gonzalez and Woods version.
>-- 
>==============================================================================
> Chris Wein                           | cjwein@watcgl.waterloo.edu 
> Computer Graphics Lab, CS Dept.      | cjwein@watcgl.uwaterloo.ca
> University of Waterloo               | (519) 888-4548

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<BvKz16.GAC@watcgl.uwaterloo.ca> <BvM3JH.8pD@cpsc.ucalgary.ca> <1992Oct05.203641.13429@bmerh85.bnr.ca> <BvpGI2.6K6@watcgl.uwaterloo.ca>

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Path: arc1-ca.pugleaf.net!sparky!uunet!munnari.oz.au!metro!cs.uow.edu.au!cc.uow.edu.au!g9024557
From: g9024557@cc.uow.edu.au (James Phillip ANDREW)
Subject: Re: Errata for Gonzalez/Wintz?
Message-ID: <1992Oct7.225326.18800@cc.uow.edu.au>
Organization: University Of Wollongong
References: <BvKz16.GAC@watcgl.uwaterloo.ca> <BvM3JH.8pD@cpsc.ucalgary.ca> <1992Oct05.203641.13429@bmerh85.bnr.ca> <BvpGI2.6K6@watcgl.uwaterloo.ca>
Date: Wed, 7 Oct 92 22:53:26 GMT
Lines: 24

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