Re: [video] Real Time Video Scaling

[Andras Ferencz <opencores@ferencz.org>]

If you want to half the number of lines, use a halfband lowpassfilter.
I don't know too much about the video part, but look first up the theory
of decimation/interpolation.

Cheers,
Andras

On Tue, 27 May 2003, Aris Konstantinos wrote:

> Hi Gents;
>
> Please correct me if I am wrong..A FIR Filter is used if there is a need to
> skip some parts of the frequency spectrum of a signal, rigth?. Could you
> please give us some more information or some resources that we can
> readly follow for this purpose? At last, what are the specifications of the
> FIR Filter (ex:is this Pass-Band, what is the sampling frequency
> selected)?
>
>
> cheers, :)
>
> Aris
>
>
> ----- Original Message -----
> From: Richard Herveille <richard@a... >
> To: video@o...
> Date: Mon, 26 May 2003 07:50:44 +0200
> Subject: Re: [video] Real Time Video Scaling
>
> >
> >
> >
> > Well down scaling is the easiest, especially if you can afford
> > loosing pixels.
> > Simply skip every second pixel and skip every second line.
> > This doesn't give the best picture, but it will work. Biggest
> > problem is that
> > a line 1 pixel/line width won't be visible when it's on the removed
> > pixel/line. You can solve this by alternating what pixel/line you
> > remove, but
> > then the image starts flickering (pixel visible, non visible,
> > visible, non
> > visible, etc)
> >
> > A better way is to filter the image using a reducing filter. This
> > can/should
> > be a simple FIR filter. The output of this filter provides a much
> > smoother
> > image and provides all the features of the original. This can be
> > done on the
> > fly for a single line. But in order to filter lines you need some
> > memory, but
> > not an entire frame.
> >
> > Upscaling (zooming) is best done with a bi-linear filter. You need
> > to store
> > the previous line for this.
> --
> To unsubscribe from video mailing list please visit http://www.opencores.org/mailinglists.shtml
>

--
To unsubscribe from video mailing list please visit http://www.opencores.org/mailinglists.shtml