From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 2B90D1382C5 for ; Tue, 12 Jan 2021 18:54:45 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id E7FC7E0AD3; Tue, 12 Jan 2021 18:54:39 +0000 (UTC) Received: from mail-qv1-xf35.google.com (mail-qv1-xf35.google.com [IPv6:2607:f8b0:4864:20::f35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 98690E0AC1 for ; Tue, 12 Jan 2021 18:54:39 +0000 (UTC) Received: by mail-qv1-xf35.google.com with SMTP id l7so1392307qvt.4 for ; Tue, 12 Jan 2021 10:54:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=+Wb7yAY8fgMAWjr/YzZX0k7amTkDPwS65gqwOMiVM2M=; b=uif8yegP8eR0h8oSsdY4txTcJ6IkRlTcIZ5ZAWxWjOjRL2M7Okh4Cq95vPHWlVz03Q sfyGd3jyKrZFFMkhDMpyAFWN0asFJwrTqR50NEDpTP5SDyfqijHGPNs4Qw896L3G6iei d0I7qaRzHkPVL51eum6xq/DkVhUQRNWayFEqdNaD7GghU7eAzm0gGdVawdzDAN8C6XKK virIGSQ8flTbk6GPHXcTPGkZBLvoeusmFmTespPgKEvsWbZjr7f3c8S97xqvLAQFLhNm y20TC/i2OhC3o/bKnCGJc/wszZFGm/gDCbiTxcIOpAebgeIXiIRvjhYPS/JKo+PySEUP wvVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=+Wb7yAY8fgMAWjr/YzZX0k7amTkDPwS65gqwOMiVM2M=; b=gQ2BJO0uu4Q+d64PHZHxbJywyp9YUoxZqobPZDb160R7NwrVhdhE36aHV6vNwzzMu7 fdMgTIRka/cIlBGAZyzTAenN58CDK1OrY1BxTjKtg29IygifVXAsda6aWQ98ATytcq0y Cjy05X1hqGBoTxzu3OLlftPIYGg7x3s32XZ6A3zNxhcv0hqKdsa7uJkN5dEdICzYWKbN KLztNMZwFq1Dh0bbfxdMTcJkTBxrtQhYq+ujea5c4QOeTq7CkptCpmIvsXxrtCRuW/gL mLZaJMRzB4Lfvl21wNZ6h/Ljg0QZYE5/59BYL47INeP0G2UMc3m6qtfG24u+sr89hmLj LrOA== X-Gm-Message-State: AOAM5308SGMV1ZQ/zHOiJg6xId5amNwI1go10Vgg/Gahpp8izpMyNixi XPsE4ZVVBOVsxnBVX8SVS+qbdiZZKZ+KCuCGhDNFj3g1ZcM= X-Google-Smtp-Source: ABdhPJyBmY44dC6U48OZlmqDqhjk3OqhyfKn88OQf4RRjVQIcIldz+o2QyE9ZCQbmKZ/2xUpq6NWjJzMRylZTFcmv1c= X-Received: by 2002:a05:6214:1485:: with SMTP id bn5mr856858qvb.17.1610477678585; Tue, 12 Jan 2021 10:54:38 -0800 (PST) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply MIME-Version: 1.0 References: In-Reply-To: From: Mark Knecht Date: Tue, 12 Jan 2021 11:54:27 -0700 Message-ID: Subject: Re: [gentoo-user] Your opinion on jpeg encoders, please To: Gentoo User Content-Type: multipart/alternative; boundary="000000000000f3757b05b8b88d9f" X-Archives-Salt: 45a60e83-f97e-40f6-8e23-bbe946c89022 X-Archives-Hash: c66689efeaf8746373c5866a0f42f97d --000000000000f3757b05b8b88d9f Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Jan 4, 2021 at 2:38 PM Frank Steinmetzger wrote: > > Hi all, > > this is not really a Gentoo-specific question, but some of you know your way > around stuff, so here goes. > > When I edit photos, I like to shrink and recompress them to save on space= , > but not mangle them too much in the process to lose quality. So for average > images I tend to use a quality setting between 80 and 86, very bad shots > such as defocussed or blurred ones just 70. And for the really good ones > (crystal sharp, portraits, extraordinary motives etc) 90 and more. > > In the far past I=E2=80=99ve been using Gimp, but for some years now most= ly Showfoto > (the editor from Digikam) due to its more useful photo enhancement features. > > However I noticed that the latter procuces larger files for the same quality > setting. So currently, I first save with a very high setting from Showfot= o > and then recompress the whole directory in a one-line-loop using > imagemagick=E2=80=99s convert. I have the impression that it produces far= smaller > files at the same visual quality. > > > Now I know that one can=E2=80=99t fully compare quality settings of diffe= rent > encoders, but it started me wondering: which is really =E2=80=9Cbetter=E2= =80=9D? Or maybe > just a little more enhanced, or up-to-date from an algorithmic standpoint= ? > > Just because many distros and tools use libjpeg, that doesn=E2=80=99t mea= n it=E2=80=99s the > best one out there. Gimp, showfoto and convert use different encoders, > because compressing the same PNG with the same JPEG setting does not result > in three identical files. > > Does any of you have an opinion on that matter? > Cheers. > > -- > Gru=C3=9F | Greetings | Qapla=E2=80=99 > Please do not share anything from, with or about me on any social network= . > > What do you call a man with a seagull on his head? =E2=80=93 Cliff. This topic comes up a lot with astrophotography. I took about 150 24M pixel shots last night. It uses a lot of disk space. >From my reading - which isn't a lot - it seems to be technically superior to simply downsample the original and then compress with jpeg if you need to go that far vs using higher jpeg compression ratios on the original. I have no data to back this up and it probably depends a lot on your source material so YMMV but it's an option. HTH, Mark --000000000000f3757b05b8b88d9f Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Mon, Jan 4, 2021 at 2:38 PM Frank Steinmetzger = <Warp_7@gmx.de> wrote:
>> Hi all,
>
> this is not really a Gentoo-specific questio= n, but some of you know your way
> around stuff, so here goes.
>= ;
> When I edit photos, I like to shrink and recompress them to save = on space,
> but not mangle them too much in the process to lose quali= ty. So for average
> images I tend to use a quality setting between 8= 0 and 86, very bad shots
> such as defocussed or blurred ones just 70= . And for the really good ones
> (crystal sharp, portraits, extraordi= nary motives etc) 90 and more.
>
> In the far past I=E2=80=99ve= been using Gimp, but for some years now mostly Showfoto
> (the edito= r from Digikam) due to its more useful photo enhancement features.
><= br>> However I noticed that the latter procuces larger files for the sam= e quality
> setting. So currently, I first save with a very high sett= ing from Showfoto
> and then recompress the whole directory in a one-= line-loop using
> imagemagick=E2=80=99s convert. I have the impressio= n that it produces far smaller
> files at the same visual quality.>
>
> Now I know that one can=E2=80=99t fully compare quali= ty settings of different
> encoders, but it started me wondering: whi= ch is really =E2=80=9Cbetter=E2=80=9D? Or maybe
> just a little more = enhanced, or up-to-date from an algorithmic standpoint?
>
> Jus= t because many distros and tools use libjpeg, that doesn=E2=80=99t mean it= =E2=80=99s the
> best one out there. Gimp, showfoto and convert use d= ifferent encoders,
> because compressing the same PNG with the same J= PEG setting does not result
> in three identical files.
>
&g= t; Does any of you have an opinion on that matter?
> Cheers.
><= br>> --
> Gru=C3=9F | Greetings | Qapla=E2=80=99
> Please do= not share anything from, with or about me on any social network.
>> What do you call a man with a seagull on his head? =E2=80=93 Cliff.<= div>
This topic comes up a lot with astrophotography. I took = about 150 24M pixel shots last night. It uses a lot of disk space.

From my reading - which isn't a lot - it seems to be t= echnically superior to simply downsample the original and then compress wit= h jpeg if you need to go that far vs using higher jpeg compression ratios o= n the original.

I have no data to back this up and= it probably depends a lot on your source material so YMMV but it's an = option.

HTH,
Mark
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