[FFmpeg-user] fftfilt

[Michael Koch]

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?

Michael