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chenhai
Visitor
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Registered: ‎02-14-2008

Questions about FIR design for Image processing.

1. How to deal with the front and end pixel, when doing a 1-D x-filter(1,k) with FIR filter?
2. How to apply a 1-D y-filter(k,1) to the input (m,n) image or a time serialized (1, m*n) image?
3. When we are talking about the down/up sample the time serialized image, does it mean sampling in row form? How to sample the ”column“ form then?
4. What is the "transpose FIR filter"?
Thanks.
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gszakacs
Professor
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Registered: ‎08-14-2007

For your first two questions:

1. How to deal with the front and end pixel, when doing a 1-D x-filter(1,k) with FIR filter?

One approach is to essentially assume there is a "mirror" on each edge of the image and create pixels as necessary to fill the filter pipeline.  For example if you need 3 extra pixels at the beginning and end of a 10 pixel row, whre your original data is p1, p2, p3, ... p9, p10,  then you would run the filter on:

p3, p2, p1, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p10, p9, p8

2. How to apply a 1-D y-filter(k,1) to the input (m,n) image or a time serialized (1, m*n) image?

While the X filtering is simple in a rasterized image, Y filtering generally requires line buffers.  It also means you'll need to use multiplier based filters rather than distributed arithmetic, because the filter is working on a different column on each successive clock cycle.  The only other approach is to have a filter per column, which can require a lot of logic if the image size is large.
-- Gabor
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chenhai
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Registered: ‎02-14-2008

Thanks very much...
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