SemanticMetadata.net

Less than 20% of Flickr images tagged …

While writing a scientific paper on tag recommendation I checked – just out of curiosity – the share of images tagged by their uploaders on Flickr. I found out that 4 out of five images are untagged and that less than 15% of images have 2 or more tags.

My method and detailed results: In general one would need a random sample for such an investigation, but a truly random sample is hard to obtain without access to the data base. Therefore I just grabbed 20,004 images from the RSS feed for recent uploads and counted the number of tagged images. Easy enough I also computed the confidence interval:

• In my sample 3,650 images were tagged with at least one tag, that makes p1=18.25%
• With alpha=0.99 p1 is in [16.84, 19.66].
• That leaves more than 4 out of 5 images untagged.
• Also in my sample 2,628 images were tagged with at least two tags, that makes p2=13,14%
• With alpha=0.99 p2 is in [11.9, 14.37].
• That means that less than 15% of the images images have more than one tag.

Some thoughts on the WIAMIS keynote of H. Bischof

In the morning I was listenting to the talk of Horst Bischof on robust people detection in surveillance scenarios. In my opinion he gave a great talk: He manages to show the nature and results of their research and motivate the usefulness and significance of results based on context and related work. He points out what the achievements are and what hasn’t been touched by his research group and why. He also visualized his results using videos which was appreciated by the audience. If I findout where the videos can be found I’ll blog the link.

WIAMIS 2008 starts today …

The 9th International Workshop on Image Analysis for Multimedia Interactive Services (WIAMIS) takes place for the next three days in Klagenfurt, Austria. As we (the Multimedia Metadata Community) organized a special session there we will gather on Thursday latest and discuss current and upcoming research topics.

While I still have some things to prepare for tomorrow I will visit Horst Bischof’s keynote talk on “Robust Person Detection for Surveillance using Online Learning” and I hope I will find some time to blog about the conference.

Related Links

• WIAMIS Program

Image Mosaics with Ajax

Did you ever think image mosaics in a web application are something that can only be rendered on server side? Well a very interesting post gives an example for the generation of image mosaics with JavaScript and Ajax. The authors employs a JavaScript binary file reader and uses the raw values from greyscale BMPs to find the mosaic. The approach for mosaic creation is simply yet effective: The overall luminance of an image is taken as “single value descriptor” and single pixels are substituted by very small BMPs.

Related Links:

• Ajax mosaic builder – The blog entry describing the Ajax way of mosaic creation
• Lire Demo – The offline way for image mosaic creation (also featuring colored images and formats different from BMP)

Scattered Images

ZeroK blogged about scattered images a concept featured on the Flickr blog. I really like these images. A selection can also be found here. I also gave it a try