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exif tags are lost after chaning the image in the media gall

Posted: Fri Aug 04, 2006 8:04 pm
by Harald Weingaertner
Hello,

maybe it isn't a bug, but i wanted to mention, that my exif tags are gone, when i change the image resolution via the media gallery. I use Image Magick 6 to handle the images.

Can anyone confirm this or guide me how to avoid this?

Thanks, Harald

Posted: Fri Aug 04, 2006 9:30 pm
by judebert
A quick Google search indicates that ImageMagick is subject to a buffer overflow security flaw with EXIF data. You sure you want to do this?

That's right, you actually modified the plugin to handle EXIF, didn't you? Nice job, as I recall.

Sorting through the rest of the Google results (wow, that buffer overflow really made the news, didn't it?), it looks like ImageMagick tries to keep the EXIF data if it can. The -strip option was added to remove it. I'm not at my development computer right now, but if we use the -strip option, removing it should preserve your EXIF data.

Posted: Fri Aug 04, 2006 9:51 pm
by Harald Weingaertner
I'm not sure, if i understand you right.

I haven't touched the media manager plugin yet.

When resizing an image into the media library you loose the exif data. I have uploaded pictures with a resolution of 3000x2000px and they have the exif data. From the moment i resize the images to 800x600 the exif data is gone.

In serendipity_event_usergallery.php i cannot find the string "strip".

I hope i'm not confusing you.

Regards, Harald

Posted: Fri Aug 04, 2006 10:20 pm
by judebert
No, I'm probably confusing myself. I'm overworked right now. I thought you had contributed an EXIF extension to the user gallery plugin, but perhaps I'm thinking of someone else.

We've got the problem nailed down. The only problem now is, why does it happen? We don't strip out EXIF data ourselves, I don't think. ImageMagic 6 claims it won't strip EXIF unless you use the -strip option.

I can't find anything in the functions_images_inc.php that would cause the "convert" command to strip tags, either. I just don't know how we're stripping the tags...

Posted: Fri Aug 04, 2006 10:26 pm
by Harald Weingaertner
Thanks judebert,

i will ask my hoster if he has configured IM to strip exif tags. I don't know if this is possible, but if you don't find anything i'll ask them ;)

I'll be back with infos.

Posted: Fri Aug 04, 2006 10:34 pm
by Harald Weingaertner
Judebert,

I AM overworked! I've had GD and NOT IM installed in my Config!

Sorry and out for today :(

Posted: Tue Aug 08, 2006 3:22 pm
by judebert
'sokay, Harald. I'm glad you figured it out!