From: Paul B Mahol <onemda@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] avfilter: add zoneplate video source filter
Date: Wed, 10 May 2023 14:42:50 +0200
Message-ID: <CAPYw7P7qREgirmjLunf6W09V8kEc1VwFHF076Ty+3b9FoG9-OA@mail.gmail.com> (raw)
In-Reply-To: <0a7eafc0-34f2-af9d-884d-e1bb9fb3a833@t-online.de>
On Wed, May 10, 2023 at 2:32 PM Michael Koch <astroelectronic@t-online.de>
wrote:
> ffmpeg -f lavfi -i zoneplate=kx2=320:ky2=240,format=gray -frames 1 -y
> out.png
>
> When you draw a line through the center, you have
> black - gray - white - gray - white - gray -black
> which means the sine wave changes its sign in the center.
> That's why zoneplates are normally calculated with cos() function.
> See also: https://en.wikipedia.org/wiki/Zone_plate#Continuous_zone_plates
I replaced sinf with cosf, and output is same, just different phase.
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
next prev parent reply other threads:[~2023-05-10 12:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-07 16:04 Paul B Mahol
2023-05-07 22:25 ` Stefano Sabatini
2023-05-07 23:30 ` Paul B Mahol
2023-05-08 20:08 ` Stefano Sabatini
2023-05-10 11:58 ` Michael Koch
2023-05-10 12:15 ` Paul B Mahol
2023-05-10 12:32 ` Michael Koch
2023-05-10 12:42 ` Paul B Mahol [this message]
2023-05-10 12:50 ` Michael Koch
2023-05-10 13:10 ` Paul B Mahol
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPYw7P7qREgirmjLunf6W09V8kEc1VwFHF076Ty+3b9FoG9-OA@mail.gmail.com \
--to=onemda@gmail.com \
--cc=ffmpeg-devel@ffmpeg.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Git Inbox Mirror of the ffmpeg-devel mailing list - see https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
This inbox may be cloned and mirrored by anyone:
git clone --mirror https://master.gitmailbox.com/ffmpegdev/0 ffmpegdev/git/0.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 ffmpegdev ffmpegdev/ https://master.gitmailbox.com/ffmpegdev \
ffmpegdev@gitmailbox.com
public-inbox-index ffmpegdev
Example config snippet for mirrors.
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git