.pdf files with cover spreads

[Michael Howard]

My issues involves ImageMagick behavior with .pdf files.

I don't work in the printing industry, so I apologize in advance for
not knowing the proper terms.

I have a set of .pdf files for magazines. These files are apparently
the same files that were sent to the print shop. For example, the
color space is CMYK.

I am using IM convert to generate .jpg page images from these files.

I have two .pdf files have a 2-page landscape "spread" for the outside
cover, so that the front & back covers are on the same landscape page.
This makes sense for printing.

One of these files has 2-page landscape spread for the inside covers
as well. The other file treats the front/back inside covers as
individual portrait pages.

I am puzzled / struggling with ImageMagick (ghostscript?) behavior
with these files. I have observed the following:

* for the file with only the outside cover spread, the spread shows up
only at the beginning. That is, it only shows up as a single image in
the .pdf file

* for the file with both outside and inside cover spreads, the spreads
show up both at the beginning and at the end. For example, when I run
"identify" the spreads show up both at the beginning and at the end of
the list of image frames.

I have observed that Adobe Reader also treats these files specially,
so I assume that there must be directives in the .pdf file which
describe this situation.

My problem is the seemingly inconsistent behavior with ImageMagick /
Ghostscript, where sometimes the cover spread is duplicated at the
back and sometimes it is not.

Q: Any advice on how to handle this issue would be greatly appreciated.


Thanks,
Michael