From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 9703246248 for ; Wed, 10 May 2023 12:32:26 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 1E69968C059; Wed, 10 May 2023 15:32:23 +0300 (EEST) Received: from mailout11.t-online.de (mailout11.t-online.de [194.25.134.85]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 7F2D968BF96 for ; Wed, 10 May 2023 15:32:16 +0300 (EEST) Received: from fwd72.dcpf.telekom.de (fwd72.aul.t-online.de [10.223.144.98]) by mailout11.t-online.de (Postfix) with SMTP id BADF1D3BA for ; Wed, 10 May 2023 14:32:15 +0200 (CEST) Received: from [192.168.178.21] ([91.60.186.201]) by fwd72.t-online.de with (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384 encrypted) esmtp id 1pwizP-1ZArYn0; Wed, 10 May 2023 14:32:15 +0200 To: ffmpeg-devel@ffmpeg.org References: From: Michael Koch Message-ID: <0a7eafc0-34f2-af9d-884d-e1bb9fb3a833@t-online.de> Date: Wed, 10 May 2023 14:32:14 +0200 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: X-TOI-EXPURGATEID: 150726::1683721935-5AFF257F-F02D8FCD/0/0 CLEAN NORMAL X-TOI-MSGID: 1ff9a474-b1be-4900-b951-378f19a080c8 Subject: Re: [FFmpeg-devel] [PATCH] avfilter: add zoneplate video source filter X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: 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 _______________________________________________ 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".