Dear Fweb – Outbound Link Tracking and Color Spaces

Dear Fweb,

Google Analytics outbound link tracking uses the sendBeacon API for browsers that support it (currently, mainly Chrome).

For other browsers, outbound link tracking requires installing a handler on all clicks that makes an AJAX call to Google Analytics and then redirects the user to the destination URL after this request returns. This introduces a slight delay on outgoing clicks, plus a dependency on Google Analytics. I recommend that you use this for your site.

At ZipRecruiter, we have essentially reproduces Google Analytics internally. This was not as hard as it might seem, since we were able to piggyback on our existing infrastructure for logging events at scale and pushing them into our data warehouse. For outgoing clicks, we wrap all links in a tracking URL, which does nothing but log the click to a file and redirect the user to the final destination. These click logs then get loaded along with pageview and other event data into our data warehouse.

Speaking of perception, color filters, and rainbows, did you know that magenta cannot be found in the rainbow? It is an extra-spectral color that requires a combination of at least two wavelengths of light to activate the long and short (blue and red) wavelength cones without activating the medium (green). This ability to discern a combination, and not just an average, of light frequencies explains why there is a color wheel and a three-dimensional color space (RGB), and not a color line and a 2-dimensional color space.

A two-dimensional color space is in fact what is seen by people suffering from dichromacy, a common type of color blindness: not the absence of color, just a small slice of the colors of the rainbow, at varying intensities.

Now, some animals, as well as at least one mutant artist (whose daughter is, very ironically but not coincidentally, colorblind), can perceive 4 dimensions of color. Each cone cell can differentiate about 100 different intensities, so the full tetrachromat can theoretically differentiate about 100^4 or 100 million colors — about 100 times the number of colors as we trichromats.

But some organisms have even more than 4 types of cone cells, and theoretically an organism could have as many types of cone cells as there are plank-lengths of light in their visible spectrum. This sort of continuously-variable-frequency vision could detect the entire spectral power distribution of a light source, or a color space of approximately 1.86^28 dimensions, for a total of 100^(1.86 * 10^28) unique colors, which is the largest number anybody has ever thought of.

It is humbling to understand that we, in fact, do perceive the world through a color filter, only slightly less limiting than that of dichromats, and what mind-boggling masses of information are reaching our eye, unseen, from each single point of light.

Maybe then, it’s hubris to worry about the single dimension of color we lose in taking advantage of the sendBeacon API to track outbound clicks in Google Analytics. We should be happy we see anything at all.

universes, whole
unseen in a point of light
we’re all color blind

August 9th, 2016 by