[FFmpeg-user] fftfilt

[Paul B Mahol]

On Thu, Oct 14, 2021 at 1:18 PM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 14.10.2021 um 13:11 schrieb Paul B Mahol:
> > On Thu, Oct 14, 2021 at 1:08 PM Michael Koch <
> astroelectronic at t-online.de>
> > wrote:
> >
> >> Am 14.10.2021 um 13:01 schrieb Paul B Mahol:
> >>> On Thu, Oct 14, 2021 at 12:59 PM Michael Koch <
> >> astroelectronic at t-online.de>
> >>> wrote:
> >>>
> >>>> Am 14.10.2021 um 12:53 schrieb Paul B Mahol:
> >>>>> On Thu, Oct 14, 2021 at 12:29 PM Michael Koch <
> >>>> astroelectronic at t-online.de>
> >>>>> wrote:
> >>>>>
> >>>>>> Am 14.10.2021 um 12:07 schrieb Paul B Mahol:
> >>>>>>> Sorry but I'm not on windows, so I can not use your script.
> >>>>>> Then try the below (slightly improved) version. It would become much
> >>>>>> simpler with variables:
> >>>>>> ARRAY_H = pow(2,ceil(log(ceil(W*10/9))/log(2)))
> >>>>>> ARRAY_V = pow(2,ceil(log(ceil(H*10/9))/log(2)))
> >>>>>>
> >>>>>> The test image contains wavelengths from 4 to 8 (in the center) to
> 16
> >>>>>> pixels per linepair.
> >>>>>> The filter wavelength is independant of input size. You can change
> the
> >>>>>> size in the first command (but it must be 1:1 aspect ratio,
> otherwise
> >>>>>> hstack would fail)
> >>>>>>
> >>>>> Since when hstack fails because of different aspect ratio?
> >>>> Because I first make the left half of the test image, then transpose
> it
> >>>> and then hstack them together
> >>>>
> >>>> The fftfilt examples do of course work with any aspect ratio.
> >>>>
> >>> I think you do not understand what aspect ratio really means.
> >> width / height
> >>
> > Doesn't all this introduces aliasing if not using power of 2 width and
> > height square dimensions?
>
> I'm not sure if I understand what you mean. Do you see a significant
> difference if you make the input size 250x250 or 256x256?
>


it did for first test.png  you sent



> Michael
>
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