On Wed, 12 Aug 2009 20:02:53 +0200 Torquil Macdonald Sørensen <[email protected]> wrote:
| Hi all! | | Does anybody know if the command "convert 1.jpg 1.pdf" does a lossy | transformation on the image data? I would like to create PDFs from JPGs without | loosing any information. | Depends... 1/ If the image data is read in and then re-written out in JPG format it is lossy. As such, if the resulting PDF re-coded the image as JPEG data then yes it is lossy. 2/ If the PDF included the JPEG data, without decoding and re-encoding then it is not lossy. 3/ If the data is decoded but stored in the PDF without using a JPEG encoding then it is not lossy, (you only get the original loss from the original encoding/decoding of the input JPEG, no further loss of quality occurs. The first case I believe is the default, so what you wrote will be lossy. The second case is not possible with Imagemagick, as IM being a image process will read and decode the JPG data. You need a specialized direct JPEG to PDF converter for that, not a generalized image processor. I do not know of such a convertor. However by setting an appropriate -compress option then you can do the third case. However it is doubtful you can get as good a compression as the original (already lossy) JPG image data. Anthony Thyssen ( System Programmer ) <[email protected]> ----------------------------------------------------------------------------- Signature lost in transit. We apologise for any inconvenience caused. ----------------------------------------------------------------------------- Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/ _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
