[scilab-Users] 3D plot of Butterworth polynomial?

[hadi motamedi]

On 11/7/10, Ronald Michaels <ron at phenotypescreening.com> wrote:
> Hi -
>
> Assuming that you want a circular filter:
>
> Take the first equation in your link below and set a and b to 1.  Then
> set the origin of the x,y axis system to the center of your image, i.e.
> x = 0 and y = 0 at center of image.  Calculate r for each x,y pixel
> location.  Then use r in the second equation in link to find the value
> of the filter for that x,y location.  Find the equivalent position in
> image coordinates (u,v) and place filter value there in Filter array.
>
> Ron
>
>
>
>
Thank you for your reply. Please find attached the exact expressions .
For the 1-D case, it is straightforward as the formula describes it .
But for the 2-D case, it needs your help as the filter center must be
at the center of the page (but not at the corner on u=0 & v=0) . For
example, please imagine an image with 480*480 size so the filter
center must be located at (240,240) . Please help me to construct such
a filter as you helped me on constructing ideal 2-D low pass filter
for my image filtering.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: formula.rtf
Type: application/rtf
Size: 604 bytes
Desc: not available
URL: <https://lists.scilab.org/pipermail/users/attachments/20101109/ad880664/attachment.rtf>