Changes

=== JPEG ===

=== JPEG ===

JPEG is a lossy image format, most image editing software can encode and decode it but it is also possible to perform certain transformations on a JPEG [[:en:Lossless data compression|losslessly]].

JPEG is a lossy image format, most image editing software can encode and decode it but it is also possible to perform certain transformations on a JPEG [[:en:Lossless data compression|losslessly]].

* [http://sylvana.net/jpegcrop/ Jpegcrop and jpegtran]: <code>jpegtran</code> is a command line app that can perform a variety of lossless transformations on JPEG files; it can be used with [http://mapivi.sourceforge.net/mapivi.shtml MaPiVi] for a GUI (although the selection preview size seems to be limited?).<!-- A better one is [<tvar|link3>http://emergent.unpythonic.net/01248401946 CropGUI]. The program is not included in Debian; the site looks credible and the author mentioned at python.org as a PEP author, but I can’t tell if it’s safe myself. --> Jpegcrop is a command line tool with similar functionality, there is also a windows version available with GUI.

* [http://sylvana.net/jpegcrop/ Jpegcrop and jpegtran]: <code>jpegtran</code> is a command line app that can perform a variety of lossless transformations on JPEG files; it can be used with [http://mapivi.sourceforge.net/mapivi.shtml MaPiVi] for a GUI (although the selection preview size seems to be limited?).<!-- A better one is [http://emergent.unpythonic.net/01248401946 CropGUI]. The program is not included in Debian; the site looks credible and the author mentioned at python.org as a PEP author, but I can’t tell if it’s safe myself. --> Jpegcrop is a command line tool with similar functionality, there is also a windows version available with GUI.

* There is an EXIF tag, “'''Orientation'''”, which tells viewer software that the image must be rotated before being displayed. Unfortunately, not all software supports the tag, so some images may have the wrong value in it unnoticed. The tag can be edited using exiftool (e.g. it can be neutralized with “<code>exiftool -Orientation=Normal</code>”). See [[Commons:Village_pump/Archive/2011/10#Autorotation_using_EXIF_tag_with_MW_1.18]] and {{pg|Commons:EXIF}} for more details. Physical rotation of the image instead of editing the tag can be ''lossy'', see {{pg|Commons:Media for cleanup|anchor=SIDETILT|Commons:Media for cleanup: Sideways pictures or pictures with noticeable camera tilt}}.

* There is an EXIF tag, “'''Orientation'''”, which tells viewer software that the image must be rotated before being displayed. Unfortunately, not all software supports the tag, so some images may have the wrong value in it unnoticed. The tag can be edited using exiftool (e.g. it can be neutralized with “<code>exiftool -Orientation=Normal</code>”). See [[Commons:Village_pump/Archive/2011/10#Autorotation_using_EXIF_tag_with_MW_1.18]] and {{pg|Commons:EXIF}} for more details. Physical rotation of the image instead of editing the tag can be ''lossy'', see {{pg|Commons:Media for cleanup|anchor=SIDETILT|Commons:Media for cleanup: Sideways pictures or pictures with noticeable camera tilt}}.

* '''[[User:Cropbot|Cropbot]]''' allows one to crop JPEGs lossless, using <code>jpegtran,</code> so one does not need the software oneself.

* '''[[User:Cropbot|Cropbot]]''' allows one to crop JPEGs lossless, using <code>jpegtran,</code> so one does not need the software oneself.