Image plugin updated (meta properties from Windows Vista/7)

[Ray]

We've just updated the ImageInfo plugin for extracting and indexing images (jpg, gif, png, tiff).

We recently had reports that the plugin was failing to extract some meta fields specified via the right-click "Properties" window (under the "Details" tab) in Windows Vista or Windows 7.

It turns out the problem is related to an unusual quirk/bug of Windows when storing such tags in the little-endian specified EXIF tags of image files. Seems that in such files, it proceeds to write the data in big-endian format.

Our updated plugin will attempt to parse the data both ways. So it should now pickup the properties specified by Vista and Seven.

Download the updated plugin from our plugins page:
http://www.wrensoft.com/zoom/plugins.html

Please let us know if you have any questions or problems.

[Ray]

It's always surprising when we dig into common file formats and see how badly messed up they are by the biggest companies and most important and widely used software.

Windows XP is reknown for corrupting image meta data (see here and here and here). But it appears that Microsoft have only improved things slightly since then and have not changed their habit of mis-implementing image meta data and EXIF fields.

We've just spent time investigating an issue with the "Tags" field in Vista and Win7's "Properties" window for image files.

Microsoft evidently expects you to delimit each tag with a semi-colon, like so:

tag1; tag2; tag3; tag4;

As when you click or use the cursor key to move back and forth between the words, it will skip between each tag this way.

However, if you specified your tags like this:

tag1, tag2, tag3, tag4

It will consider this as one single tag. The cursor keys will skip over the whole string.

Now, it might seem like this is all fairly trivial and insignificant. However, we've found that this expectation leads to several bugs and issues.

It seems that Win7 corrupts the EXIF header when it stores a Tags field which contains comma characters.

Win7 itself is able to retrieve the field but most other 3rd party products I've attempted fails (as do our Image plugin) as the expected EXIF tag (40094) is completely replaced.

If you specify comma-separated tags in Vista however, they will be intact and retrievable. BUT, Vista itself gets very confused. For example, entering the following in Vista's "Tags" field (note that Windows automatically add the ";" at the end):

tag1, tag2, tag3, tag4;

Then click on "Apply", close the window, and re-open the "Properties" window, Vista will now report the Tags field to be:

tag1, tag2, tag3, tag4; tag1, tag2, tag3, tag4;

So Vista seems to get confused with commas in the "Tags" field, but it does not corrupt the EXIF header.

The only conclusion we can come to, from what we can tell, is that Microsoft does not expect you to use commas anywhere in the "Tags" field of the image "Properties" window in Vista and Win7. Despite that, Zoom will be able to retrieve those comma-separated Tags specified with Vista but not Win7 - which is similar to most third-party EXIF reading products we've also tested with.