Re: bandpass filter for 2D Data

[macy]

Color?

If luminance, only I would (symbolically represented)

>> image1 = lowpass(image,20);
>> image2 = lowpass(image,50);
>> then,
>> imageresult = image1 - image2;

I low pass filter my 2D images using a custom filter function I wrote that
preserves the 'slope' at the edges.  Does NOT preserve curvature, but at
least doesn't "squash" the edges towards zero.

Robert

> Hi
>
> does anyone have an implementation of a 2D bandpass filter?
>
> Suppose I've 2d data in a matrix of 1000 x 1000 pixels which
> represents a spatial extension of 1 m (1 mm per pixel).
> Now I'd like to filter away all frequencies below a wavelength of 50
> mm and above a wavelength of 150 mm,
> so the resulting data should only have frequencies corresponding to
> wavelengths between 50 and 150 mm.
>
> Any octave examples for this?
>
> --
> Johannes