Stephen Davies wrote:
Last week I posted a request regarding comments in JPEGs and their
apparent effect on Motorola 3G telephones.
Since then I have found that a) the issue seems to affect all WAP phones
and b) it is not just comments that cause the problem.
It seems that these devices can only handle very simple images and those
generated by Mapserver/GD fall outside their capabilities.
I have found that, as well as removing the comments from my map images,
I have to go further.
My current work-around is to use a PERL script to generate the map image
to disk and then use the mogrify utility from Image Magik to "clean"
it. The mogrify command is simply:
mogrify -quality 100 image.jpg
but whatever this does to the image is enough to make it displayable on
a telephone when sent as an img src=.
If anybody knows more about what is happening here and/or what the
underlying problem is, I would love to hear it.
I don't really know a lot of details about what you're doing, but I do
know that in my experience, phones don't like progressive JPEGs so I
turn that option off (INTERLACE OFF for older versions or FORMATOPTION
"INTERLACE=OFF" for newer versions that use an OUTPUTFORMAT block). I
think it's enabled by default, so if you don't have an INTERLACE
setting, it's most likely creating progressive JPEGs. (I'd guess
mogrify may be re-encoding from progressive to non-progressive, and
that's why you're seeing the behavior you're seeing.)
--
Jeff Hoffmann
Head Plate Spinner
PropertyKey.com
