  Privacy has deteriorated in the world wide web ever since the 1990s. The
tracking of browsing habits by different third-parties has been at the center
of this deterioration. Web cookies and so-called web beacons have been the
classical ways to implement third-party tracking. Due to the introduction of
more sophisticated technical tracking solutions and other fundamental
transformations, the use of classical image-based web beacons might be expected
to have lost their appeal. According to a sample of over thirty thousand images
collected from popular websites, this paper shows that such an assumption is a
fallacy: classical 1 x 1 images are still commonly used for third-party
tracking in the contemporary world wide web. While it seems that ad-blockers
are unable to fully block these classical image-based tracking beacons, the
paper further demonstrates that even limited information can be used to
accurately classify the third-party 1 x 1 images from other images. An average
classification accuracy of 0.956 is reached in the empirical experiment. With
these results the paper contributes to the ongoing attempts to better
understand the lack of privacy in the world wide web, and the means by which
the situation might be eventually improved.
