Re: Reduire les JPEG (ex OGG->OGG)
Christophe Courtois a écrit, samedi 20 septembre 2003, à 10:31 :
[...]
> PS : Dans le même esprit, quelqu'un a un outil à conseiller pour
> retailler en masse des images (jpegs) pour un écran bien plus petit ?
> (But principal : réduire la taille de ces Jpegs, et leur temps
> d'affichage sur le Palm)
$ jhead -h
Program for extracting Digicam setting information from Exif Jpeg headers
used by most Digital Cameras. v2.0 Matthias Wandel, Dec 11 2002.
http://www.sentex.net/~mwandel/jhead
Usage: jhead [options] files
[...]
-st <name> Save Exif thumbnail, if there is one, in file <name>
If output file name contains the substring "&i" then the
image file name is subsitute for the &i. Note that quotes around
the argument are required for the '&' to be passed to the program.
An output name of '-' causes thumbnail to be written to stdout
[...]
-cmd command
--> Apply 'command' to every file, then re-insert exif and command
sections into the image. &i will be substituted for the input file
name, and &o (if &o is used). Use quotes around the command string
This is most useful in conjunction with the free ImageMagic tool.
For example, with My Cannon S100, which suboptimally compresses
jpegs I can specify
jhead -cmd "mogrify -quality 80 &i" *.jpg
to re-compress a lot of images using ImageMagic to half the size,
and no visible loss of quality while keeping the exif header
Another invocation I like to use is jpegtran (hard to find for
windows). I type:
jhead -cmd "jpegtran -progressive &i &o" *.jpg
to convert jpegs to progressive jpegs (Unix jpegtran syntax
differs slightly)
Sur une série de photos numériques, la première option citée est /très/
rapide, et me donne des vignettes 100x75.
--
Jacques L'helgoualc'h
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