Avoiding loss of EXIF when using convert -density
Posted: 2010-05-21T07:46:55-07:00
Hi at all,
I am working on a small enhancement of a workflow-system. Users deliver some photos to the system and these photos have typically a resolution of 72 x 72 DPI and containing EXIF metainformation.
As those photos are used for printing in magazines the idea is to have a hot folder on the system and change the resolution. At the moment I have no idea how I should deal with the hot folder thing, but I will do this later as I decided first to see if IM will help me for the resolution change.
So what I did so far is a command-line test:
(Just working on WIndows 7, but it must be implemented on a linux-box - Suse Linux Enterprise 10 SP2)
OK, this seems to work fine but I have two questions here:
1.)
With this operation I loose the integrated EXIF information of the photo.
What can I do to avoid the loss of the EXIF data as we need them later in the workflow for some decisions?
2.)
I realized that I have a gap in the graphics size.
in.jpeg = 3.001.842 Bytes
out.jpeg = 3.545.200 Bytes
So the output-file is larger than the input-file. But if I understand the IM-manual right '-density' should not affect the graphics content.
So what happens here?
Is it a re-compression of the JPEG?
How can I avoid this?
I am absolutely new to IM and I am also not very familiar with the details of computergraphics but I hope I am not to wrong
Best regards and thanks for helping me!
I am working on a small enhancement of a workflow-system. Users deliver some photos to the system and these photos have typically a resolution of 72 x 72 DPI and containing EXIF metainformation.
As those photos are used for printing in magazines the idea is to have a hot folder on the system and change the resolution. At the moment I have no idea how I should deal with the hot folder thing, but I will do this later as I decided first to see if IM will help me for the resolution change.
So what I did so far is a command-line test:
Code: Select all
convert c:\sample\in.jpg -density 300x300 c:\sample\out.jpg
OK, this seems to work fine but I have two questions here:
1.)
With this operation I loose the integrated EXIF information of the photo.
What can I do to avoid the loss of the EXIF data as we need them later in the workflow for some decisions?
2.)
I realized that I have a gap in the graphics size.
in.jpeg = 3.001.842 Bytes
out.jpeg = 3.545.200 Bytes
So the output-file is larger than the input-file. But if I understand the IM-manual right '-density' should not affect the graphics content.
So what happens here?
Is it a re-compression of the JPEG?
How can I avoid this?
I am absolutely new to IM and I am also not very familiar with the details of computergraphics but I hope I am not to wrong

Best regards and thanks for helping me!