FAQ

  1. PICURL
    1. What makes picurl unique?
    2. Why doesn't picurl have a GUI (yet)?
    3. How much does picurl cost?
    4. May I use picurl for commercial purposes?
  2. METADATA
    1. What is Metadata?
    2. What are EXIF and IPTC?
    3. How can metadata help me?
    4. But Flickr, Picasa, phpGallery etc. all seem to understand EXIF and IPTC …
    5. And what about all those nice APIs from photosharing services?

PICURL

What makes picurl unique?

picurl has quite a few innovative features that are helpful for photographers, art buyers, multimedia artists etc:

  • storage indepentent tagging: picurl allows you to tag or annotate photos, no matter where you stored them (even on read-only-media!).
  • a slim, portable version of your entire photo collection using placeholder thumbnails.
  • metadata translation: picurl translates proprietary metadata from flickr.com to standard EXIF and IPTC tags, allowing a wide range of programs to work with this data.
  • copy-on-the-fly between photo stores (e.g. from a FTP-Server to Flickr).

^

Why doesn't picurl have a GUI (yet)?

picurl doesn't have one GUI, it has thousand potential GUIs - as our tutorial section shows, picurl can integrate into many existing photo editors/viewers/management tools. We believe that this "teamwork" is more valuable for our users than some half-baked GUI.

Furthermore picurl is a very young project and we like to focus on our unique features instead of repeating things that are already implemented in dozens of other applications. Viewing photos in a fancy GUI is definitely one such thing. ^

How much does picurl cost?

picurl is free in both senses of the word and licensed under the GPLv3. ^

May I use picurl for commercial purposes?

Yes, you are free to do so without charge, but be aware that picurl is currently at a very early stage of development and not yet ready for production use. If you plan to implement a software solution based on picurl, be sure to meet the requirements of the GPLv3 license. ^

METADATA

What is Metadata?

This term is generally used for data that describes other data. Usually, metadata classifies the base data in a concise way and can be accessed much faster. A good example is the short back-cover summary of a book - you can read the contents at a glance. So you find interesting books much faster than by browsing them.

Also your digital photos contain metadata, provided by your camera (e.g. the width and height of the photo, which camera settings were used during the shooting) and/or by you (describing the photo with keywords, captions and credits). The purpose is the same: a metadata-capable program just needs to read a few bytes from the photo file and can e.g. tell you about the resolution of the picture or if it was shot at night. Of course you can also get this information by opening the photo in an image editor, but with a lot of photos this process becomes rather ineffective. ^

What are EXIF and IPTC?

When you take a photo with a digital camera, the device not only saves the resulting pixels but also the technical parameters of the recording (Flash used, Aperture time, Image resolution,...). All this technical metadata is saved under the EXIF standard. The IPTC-NAA standard allows you to save human-generated metadata like captions, keywords or credits.

Both standards allow arbitrary programs or cameras to read and write metadata from/to your images. EXIF and IPTC have been around since decades, so hundreds if not thousands of image editing tools, photo management applications or content management systems support them. The maybe best-known are Adobe Photoshop, GIMP, IrfanView, Apple iPhoto, Corel Photo Paint,... ^

How can metadata help me?

Imagine, you want to find all pictures showing you and your friend Brian. Without metadata, you would have to browse your whole photo collection. With metadata, you can simply run a search for the keywords "brian, me" (assuming that you previously assigned keywords/tags to your photos). ^

But Flickr, Picasa, phpGallery etc. all seem to understand EXIF and IPTC tags. So where is the problem?

Photosharing platforms and Online Photo galleries can only IMPORT EXIF AND IPTC data, but then store keywords, captions and other metadata in their own, proprietary databases. We don't know of any service that allows you to EXPORT a photo with a complete metadata set (meaning the original metadata of the photo plus the information you added in the service, e.g. a new geotag). ^

And what about all those nice APIs from photosharing services?

Many photosharing services offer APIs (Application Programming Interface), that allow third-party programs/scripts to interact with the service. These APIs are commonly used to automate photo management tasks (e.g. uploading photos, getting/editing metadata of photos). picurl itself makes use of APIs.

However, those APIs are no replacement for the established metadata standards EXIF, IPTC and XMP. While these standards have been around since decades, APIs sometimes change within months - resulting in malfunctioning 3rd party tools.

So there are hardly any applications that support managing pictures from photosharing services. And the few that are existing, only support either Flickr or Picasa.

Here is where picurl comes into play: it translates the proprietary metadata to standard EXIF and IPTC tags, so that nearly any photo management software understands it. ^