Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.compression > #208

Re: removing predictable crap from poor quality jpegs

From human <noreply@elfavo.com>
Newsgroups comp.compression
Subject Re: removing predictable crap from poor quality jpegs
Date 2011-05-03 18:10 +0200
Organization humanity
Message-ID <4DC028EF.4A9DE7BD@elfavo.com> (permalink)
References <877ha8xeex.fsf@bazspaz.fatphil.org> <4DBFECD7.A3180162@elfavo.com> <eZA*OAaCt@news.chiark.greenend.org.uk>

Show all headers | View raw

Phil Carmody wrote:
> 
> > Then use the following command:
> 
> >   jpegtran -scans scans.txt | jpegtran
> 
> Wow, I never realised there was such an option. Looking at the
> wizards.txt file seems to explain enough about such tricks.

Yes, there is lots of flexibility by using progressive mode
parameters with custom scan script for special applications.

But be aware of the constraints when first looking into this.
A naive idea may suggest the single line:

  0,1,2: 0-62, 0,0 ;

to achieve the goal in one sequential step, but this is probably
prevented by the constraint checking in the JPEG code.
For sequential mode only 0-63 is allowed, and note that progressive
mode must always separate DC from AC scans, because the coding
models for DC and AC are different anyway.
Note further that progressive mode also requires that an AC scan
may contain only a single component, whereas DC scans can be
interleaved with multiple components.
That AC scan restriction is not accidentally chosen, it provides
option to the optimized AC coding model with EOBrun symbols
spanning multiple blocks (which would not work interleaved).
Beside those restrictions, the JPEG code permits notable liberality
regarding "incomplete" progressive scan configurations with issue
of warnings, which can be useful occasionally as shown here.

ciao
human

Back to comp.compression | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

removing predictable crap from poor quality jpegs Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-03 13:32 +0300
  Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-03 13:53 +0200
    Re: removing predictable crap from poor quality jpegs Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-03 16:09 +0100
      Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-03 18:10 +0200
        Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-03 18:32 +0200
  Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-03 06:22 -0700
    Re: removing predictable crap from poor quality jpegs Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-05-03 18:03 +0300
      Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-05 04:18 -0700
        Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-05 13:35 +0200
          Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-06 00:23 -0700
            Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-06 14:24 +0200
              Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-06 20:33 +0200
                Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-08 09:52 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-08 15:27 +0200
                Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-08 17:55 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-08 07:56 -0700
                Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-08 18:44 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-08 10:21 -0700
                Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-09 10:51 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 11:49 +0200
                Re: removing predictable crap from poor quality jpegs human <noreply@elfavo.com> - 2011-05-09 12:06 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 15:29 +0200
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <gv@uc.ag> - 2011-05-09 16:03 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-09 22:01 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 23:24 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-10 16:45 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-09 04:15 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-09 14:26 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 15:51 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-09 21:09 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 22:28 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-09 23:06 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-10 17:34 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-12 15:01 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-09 09:40 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-09 20:23 +0200
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-09 22:37 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-10 02:27 -0700
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-10 05:01 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-12 15:51 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-13 05:07 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-13 14:39 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-13 15:39 +0200
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-13 16:36 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-13 08:52 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-13 19:00 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-13 10:07 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-13 17:25 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-13 10:06 -0700
                Re: removing predictable crap from poor quality jpegs Pete Fraser <pfraser@covad.net> - 2011-05-13 18:17 -0700
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <guido@jpegclub.org> - 2011-05-14 09:16 +0200
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <guido@jpegclub.org> - 2011-05-14 10:07 +0200
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <guido@jpegclub.org> - 2011-05-14 19:52 +0200
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <guido@jpegclub.org> - 2011-05-14 21:08 +0200
                Re: removing predictable crap from poor quality jpegs Guido Vollbeding <guido@jpegclub.org> - 2011-05-16 08:43 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-16 05:15 -0700
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-16 17:00 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-16 13:02 -0700
                Re: removing predictable crap from poor quality jpegs Thomas Richter <thor@math.tu-berlin.de> - 2011-05-17 09:43 +0200
                Re: removing predictable crap from poor quality jpegs Sebastian <s.gesemann@gmail.com> - 2011-05-19 02:55 -0700
                Re: removing predictable crap from poor quality jpegs Noob <root@127.0.0.1> - 2011-05-20 13:23 +0200
                Re: removing predictable crap from poor quality jpegs Pete Fraser <pfraser@covad.net> - 2011-05-20 05:38 -0700
                Re: removing predictable crap from poor quality jpegs human <noreplay@elfavo.com> - 2011-05-12 20:15 +0200

csiph-web