Location data from .png pictures

[hcmh]

Hello,

I noticed the following pattern in my test of the openstreetmaps extension: It seems like location information is only found for .jpeg images, not for the .png images I uploaded.

Is it possible that this plugin does not read exif loction information from .png's?

Thank you so much for your work on this extension!

[xbgmsharp]

Hello,

EXIF data for PNG file format does not exist. That is why there is filter on jpeg or jpg files. http://stackoverflow.com/questions/19492969/how-can-i-extract-gps-exif-info-from-a-png http://stackoverflow.com/questions/9542359/does-png-contain-exif-data-like-jpg

Also as part of PWG2.6, EXIF information are read directly by PWG core. So there is no more code to read EXIF data in the latest version v2.6a, https://github.com/xbgmsharp/piwigo-openstreetmap/releases.

However, openstreetmaps extension allow you to set an GPS information directly in PWG via the photo-edit page.

In any case, if you have PNG file with GPS information, I could add support for it. You will need to provide me sample and a tool to read it.

[hcmh]

That is very interesting, I did not know that there isn't a standard way to write EXIF to PNG.

Here, for example, is a sample image with metadata (created by digikam http://digikam.org/). ExifTool (http://en.wikipedia.org/wiki/ExifTool) seems to find exif data embeded in the image (with 'exiftool -a -EXIF:all'), and 'exiftool -a -gps:all' finds GPS information: GPS Version ID : 2.0.0.0 GPS Latitude Ref : North GPS Latitude : 59 deg 58' 0.85" GPS Longitude Ref : East GPS Longitude : 10 deg 40' 26.43" GPS Altitude Ref : Above Sea Level GPS Altitude : 405.6 m GPS Map Datum : WGS-84

But, since this is an external Perl program, I am not sure if it can be used for this extension. In any case, it is not much work to just convert to .jpeg before uploading.

Thank you for your time!

[xbgmsharp]

In fact the limitation is not in PWG but in the PHP function probably due to the lack of standard. http://www.php.net/manual/en/function.exif-read-data.php

However I found a way to read the PNG metadata using your sample: http://www.php.net/manual/en/imagick.getimageproperties.php

exif:GPSAltitude => 2028/5
exif:GPSAltitudeRef => 0
exif:GPSInfo => 10918
exif:GPSLatitude => 59/1, 58/1, 4462/5269
exif:GPSLatitudeRef => N
exif:GPSLongitude => 10/1, 40/1, 74875/2833
exif:GPSLongitudeRef => E
exif:GPSMapDatum => WGS-84
exif:GPSVersionID => 2, 0, 0, 0

As the GPS sync in now part of PWG core, you can create a request on the forum. http://piwigo.org/forum/viewforum.php?id=13

It is not too complex to use imagick if file ext is PNG for the GPS sync.

  $exif = @read_exif_data($filename);
  if (!is_array($exif))
  {
   /* Create the object */
   $im = new imagick($filename);
   /* Get the EXIF information */
   $exifArray = $im->getImageProperties("exif:*");
   /* Loop trough the EXIF properties */
   foreach ($exifArray as $name => $property)
   {
     $key = preg_split("/:/", $name);
     $exif[$key[1]] = $property;
   }
  }

[xbgmsharp]

I might provide a patch to PWG team for support PNG EXIF data. Anyway it is not anymore in the plugin so closing.