Re: [gentoo-user] Re: Your opinion on jpeg encoders, please

[Frank Steinmetzger]

Am Thu, Jan 07, 2021 at 05:12:07PM +0000 schrieb antlists:
> On 07/01/2021 02:22, Nikos Chantziaras wrote:
> > On 04/01/2021 23:37, Frank Steinmetzger wrote:
> > > 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
> > > Showfoto
> > > and then recompress the whole directory in a one-line-loop using
> > > imagemagick’s convert.
>
> > You lose some extra quality when doing this due to recompression. What
> > you should do is save in a lossless format (like png or bmp) and then
> > convert that to jpg.

But that would lose a lot of EXIF stuff in the process. I know that
recompression reduces quality, that’s why I use a very high setting
(98…100) for the intermediate file.

> If you're doing that (which I recommend), I set my camera to "raw + jpeg",
> and then dump the raw files to DVD. That way, it doesn't matter what happens
> to the jpegs as you can always re-create them.

I don’t really live the RAW way. They take up sooo much space and my
camera’s OOC jpegs always look far nicer than anything I can produce with
darktable/rawtherapee. Most of the time there are colour fringes and
sometimes sensor patterns that I can’t get rid of. I already have a backlock
of several 100, if not 1000 pictures. Working from RAW would take even more
time. In some specific scenes I actually use RAW+Jpeg, mostly in scenes with
a very high dyamic range. But as I said, the results are not very
satisfactory.

> If you've only got jpegs (why are you using a rubbish camera :-)

I have an Olympus O-MD E-M5 MkII and a MkIII, that’s far from rubbish. ;-)
But the OOC jpegs are so good that I don’t need a lot of post-processing.
I tend to read manuals and set up my equipment to get the best result right
away, rather than point+shoot and do the enhancements later.

> then just dump the original jpegs to DVD - that's why what Google do is so
> bad - they compress it to upload it from your Android phone, and then
> delete the original! AND THAT'S THE DEFAULT !!!

I do some light enhancements on my images (like local contrast, exposure
correction, alignment), shrink them to – say, 6 MP – and only keep the
result. With convert, this gives me about 500 kB to 2 MB files, depending on
the scene and chosen quality from 70 to 90. For 95 % of cases, that’s
enough. There are exceptions of course, such as portraits, or the odd
animal picture captured in just the right moment.

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