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List:       linux-video
Subject:    Re: [V4L] Turning odd fields into even.
From:       "Gleicon S. Moraes" <gleicon () uol ! com ! br>
Date:       2001-07-26 11:35:19
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>
> Well, I was not too clear. What I intend to do is not interpolate
> (add/mix lines) odd+even fieds. My intention is to display/store even
> fields untouched but change the odd ones so that the half black line is
> not displayed and the image does not suffer from a half-pixel vertical
> displacement.

Oh, sorry. So. I think your problem is the shift between these fields, so,
capturing only the even field and interpolating it, you could solve it.

>
> I know it is possible to do so with an interpolation routine which uses
> the captured odd frame to approximate what would be the values of the
> even field pixel lines.
>
> Does anyone have any information on this?

I've seen it in many ways. The simplest way, perhaps not so clear and right,
was to do something like a vertical aproximation, like:

given a simple function called pixel(row, column), who returns the pixel
from the give position, and your even image, imagine it as (x,y) array,  say
it only has valid data in the even lines (0,2,4,6, etc), you will fill the
odd lines as:

pixel(1, 0) = (pixel (0,0) + pixel (2,0))/2;
almost a median calculation, done only in the black lines.

and so on...
This is the simpliest way that I've seen working on it. For more accurate
data, you should try gaussian interpolation, or another numeric magic.
Excuse me, I am not that math expert, just had some experience on it.
As it is not the main subject of this list, feel free to mail me directly if
you think I can help more...

Regards

Gleicon S. Moraes







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