I recently learned that jpegtran from the JPEG library has the ability to crop and save a new jpeg losslessly:
These transformations are each completely lossless and reversible. The transformations on the image data comprise: · eliminate non-standard application-specific data inserted by some image programs, · perform certain transformations on a file, such as: o discarding of colour channels (conversion to greyscale), o rotating and flipping in steps of 90 degrees, o cropping at image block borders (every 8×8 or 16×16 pixels), o rescaling.[7]<https://en.wikipedia.org/wiki/Libjpeg#cite_note-jpegtran-7> These are lossless and reversible only regarding the image data that is kept. Reencoding with repeated lossy quantisation of the image data (generation loss) does not take place. -- https://en.wikipedia.org/wiki/Libjpeg#jpegtran Can GDAL take advantage of this for jpeg-in-geotiff images? Matt Wilkie Geomatics Analyst Environment | Technology, Innovation and Mapping T 867-667-8133 | Yukon.ca<http://yukon.ca/> Hours: 08:30-16:30, Tue-Wed: Office, Thu-Fri: Remote.
_______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
