Legacy ImageMagick Discussions Archive

Hi,
I´m trying to create lay files from high res tif und jpg files. From the old days I remember just to change the file size by creating a 72 dpi version of the high res pics but that doesn´t work. What I do (in a bash script on FreeBSD 9): convert -density 72x72 input.jpg output.jpg. This reduces the file size for around 3 %. First I thougth something went wrong but opening the files in OS X preview shows that "input.jpg" has 300 dpi and output.jpg has 72 dpi.
For a better understanding: the lays are needed for pre press working, so you do the layouts with the low res pics for faster working and for the printing you just replace the lowres pics with the highres.
What´s wrong?

Best regards,

Mike

I believe you have the wrong command. -density will not change the pixel file size only the size of the printed file. try

convert input.jpg -quality XX output.jpg.

see
http://www.imagemagick.org/script/comma ... hp#quality


P.S.

Next time please post such messages to the User's forum if they pertain to how to use IM commands. The Digital Image Processing forum is more for general image processing issue that are not IM specific commands.

First, sorry for the long delay, some other problems came up, holidays (happens to the best of us) but now I´m back on the track.
So thanks for the reply, it works as expected but only for jpgs (as described) but not for tiffs.
But for this I will close this thread here and switch over to the User´s forum to ask my question there.

Many thanks so far,

Mike

Moving thread to Users forum.