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Re: Digest Number 131

Started by gaurav February 26, 2005
I have generated 2D hamming from 1d successfully in the past. Here is what i did
suppose u have a one row of 32 element 1D hamming window. And now you want to generate a 2d window. So just copy the same elements to 32 rows to make a 32 x 32 matrix .
Then take its transpose and multiply it by itself. In the end normalize by dividing it by the maximum. You will get a 2d hamming window.
 
Algo:
1)  h[1][1 --> 32] = 1D hamming window
2) h[2][1--->32] = h[1][1 --> 32] ;
         |                        |
         |                        |
    h[32][1--->32] = h[32][1 --> 32] ;
 
3)  let h* = transpose of h
4) 2d hamming =  h x h* ( element by element multiplication)
5) Find the max of the 2d hamming matrix and divide all matrix elements by it to normalize it.
 
Hope it helps
Gaurav
 
 


i...@yahoogroups.com wrote:

There is 1 message in this issue.

Topics in this digest:

1. Help: How to convert 1d Hamming filter to 2D one
From: "jlin_nb" ________________________________________________________________________
________________________________________________________________________

Message: 1
Date: Fri, 25 Feb 2005 15:02:50 -0000
From: "jlin_nb"
Subject: Help: How to convert 1d Hamming filter to 2D one
Hi there,
I have 1D hamming mathematical form
H(v)=0.54+0.46*cos(2*PI*v/Vmax)

Could you help me to get 2D Hamming filter from this 1D one.
I need to use it to filter my images

Thanks a lot.

Jian________________________________________________________________________
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Gaurav Sharma
Imaging Research Associate , Omnicorder Technologies
M . S Electrical Engineering and Biomedical Engineering
phone: 631-897-0438
email: g...@omnicorder.com





> Date: Fri, 25 Feb 2005 15:02:50 -0000
> From: "jlin_nb" <>
> Subject: Help: How to convert 1d Hamming filter to 2D one
>
> I have 1D hamming mathematical form
> H(v)=0.54+0.46*cos(2*PI*v/Vmax)
>
> Could you help me to get 2D Hamming filter from this 1D one.
> I need to use it to filter my images

Jian,

Two possible methods immediately spring to mind:

cos(2*PI*v1/V1max)*cos(2*PI*v2/V2max)

or

cos(2*PI*sqrt((v1^2+v2^2)/(V1max^2+V2max^2)))

Of cource you need to check the spectral forms in both cases
and use the best one.

Regards,

Andrew



hello everyone,

i have a doubt in performing 2-D hadamard transform.for finding the 2-d transform whether 1-d transform has to be performed first horizontally or vertically.it was given some where that for finding 2-d transform 1-d has to be performed both horizontally and vertically.can u plz say me which has to be done prior to the other.
thanx in advance
regards
chandrika
"Always be with a smiling face and singing heart"
--Chandrika villuri




I think you can do it either way .Complete the rows and then the columns or vice versa

chandrika <chandrika6@chan...> wrote:
hello everyone,

i have a doubt in performing 2-D hadamard transform.for finding the 2-d transform whether 1-d transform has to be performed first horizontally or vertically.it was given some where that for finding 2-d transform 1-d has to be performed both horizontally and vertically.can u plz say me which has to be done prior to the other.
thanx in advance
regards
chandrika
"Always be with a smiling face and singing heart"
--Chandrika villuri

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