There was a post on Hacker News not long ago about a color, and it was just a link to wikipedia. Not long after, some wizard removed this handy infobox from that page. I'm posting it here. That's it.

Eigengrau (German: "intrinsic gray"), also called Eigenlicht ("intrinsic light"), dark light, or brain gray, is a term for the uniform dark gray background that many people report seeing in the absence of light. The term dates back to the nineteenth century^[1], but has rarely been used in recent scientific publications. A literature search finds that the most recent mention of the term in a scientific journal article dates from the year 2000.^{[2][original research?]} Nowadays the phenomenon is more commonly referred to as "visual noise" or "background adaptation".^[3]

Eigengrau is perceived as lighter than a black object in normal lighting conditions, because contrast is more important to the visual system than absolute brightness.^[4] For example, the night sky looks darker than eigengrau because of the contrast provided by the stars.

Cause

Researchers noticed early on that the shape of intensity-sensitivity curves could be explained by assuming that an intrinsic source of noise in the retina produces random events indistinguishable from those triggered by real photons.^[5][6] Later experiments on rod cells of cane toads (Bufo marinus) showed that the frequency of these spontaneous events is strongly temperature-dependent, which implies that they are caused by the thermal isomerization of rhodopsin.^[7] In human rod cells, these events occur about once every 100 seconds on average, which, taking into account the number of rhodopsin molecules in a rod cell, implies that the half-life of a rhodopsin molecule is about 420 years.^[8] The indistinguishability of dark events from photon responses supports this explanation, because rhodopsin is at the input of the transduction chain. On the other hand, processes such as the spontaneous release of neurotransmitters cannot be completely ruled out.^[9]

View On Wikipedia

Eigengrau
Color coordinates
Hex triplet	#16161D
sRGBB    (r, g, b)	(22, 22, 29)
CMYKH   (c, m, y, k)	(24, 24, 0, 89)
HSV       (h, s, v)	(240°, 24.1%, 11.4%)
Source	[citation needed]
B: Normalized to [0–255] (byte) H: Normalized to [0–100] (hundred)
Lighter sample

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I have a basic nginx (pronounced Engine EX) configuration on github. This is a basic version of perusio's nginx configuration in more of a stand-alone set up - and it uses unix sockets in the PHP connection configuration to do the processing instead of an upstream configuration (where the processing could optionally be coming from another server that has PHP), that can include Apache web servers. perusio's config is an advanced configuration with multiple failover backup servers that just wasn't necessary in my case so I decided to make another example config on github. Instead of having PHP connect to itself using TCP/IP, this setup eliminates the need for communication with itself using the TCP network layer. Data does not have to be "converted" into a standardized network layer format as it's processed from the file system through PHP. A performance enhancement side effect for stand alone nginx web servers.

For stand-alone-ish servers, doing this processing via a regular Unix socket is basically more the norm. Certainly a chance to get more out of your stand-alone nginx server versus using TCP. As mentioned, Perusio's set up includes upstreams for other webservers balancing the giant enterprise load it's configured for. My set up is one small server and a really, really fast website. I am now very pro-nginx since setting up and seeing the difference in just my browser load times.

There is support for Drupal 6 and 7, just use the appropriate include file in your virtual host configuration file. See the example.conf. I like to keep virtual host configs in separate files in the conf.d folder. With all the defaults set throughout the operational files in the root of the config, the individual config files per virtual host are small, easy to read, and easily identifiable (any .conf file in the conf.d/ folder will be parsed on nginx start up; so call it good practice to name your config files after the sites they represent - like mysite.conf or mysite.ca.conf). The files in the configuration directory "conf.d" can also be linux soft links - so if you need to allow users to make edits to their own config files they can - without letting them into the main nginx directory.

Mixing this config with perusio's micro-caching stanzas has been left as an exercise to the reader!

Also, worth a look is yhader's boost-compatible nginx configuration. While dated, it was built for Drupal and supports the Boost module, and it also proves the simplicity of a standard nginx set up. Nginx.org has a very good wiki and clear documentation. If you're doing anything with nginx, start there. This configuration is a work in progress. Check back for updates or follow me on Twitter! @slozzy