title: Creating an image of PNG-format in php with GD with exif
body: <p>I am looking for a way to create a PNG-image in PHP
  with some settings in EXIF tags.
  How do I achieve this and are able to read these tags from the PNG-file when created?
  I have tried the header("Key: ", value); but it doesn't work.
  Any suggestions?
  How can I read the data from the files? I guess they will end up in the "png:IHDR", but how can I read this?
  I can not use ImageMagick.</p>
  
  <p>How can I see the tags (what tool is good)?</p>