Sept 2019 note (unrelated to the post below): Anyone looking for embyrne.co.nf, please note that it has provisionally moved to embyrne.c1.biz due to a problem with the co.nf domain – apologies!
It occurred to me that one of my recent webcode tinkerings has a tangential connection to an aspect of last month’s topic of World Wide Wonderment, the colour of that little black/blue/white/gold dress (see e.g. Wired’s article for one discussion). Assuming there is some real differences in experience (and that might not be a small assumption…), perceived background lighting/context/colour probably does have some bearing. There are many demonstrations of ‘background’ effect presented on the web, and the famous “checker shadow illusion” (right) provides a striking greyscale illustration.
To see some examples ‘dynamically’ at the Colour Player, set up a colour in the display box, e.g. 127 each red and green gives a ‘dark yellow’ , or ‘greenish gold’ as I like to think of it. Then hit the button labelled “Option: Set test colour values as for current display” followed by “Click to display random number with test colour”. This puts an ‘invisible’ random number of the same colour in the display box. Now increase red – a greenish number will emerge. Go back the other way (decrease red) and the number fades into the background then re-emerges before your eyes looking orangish, although its colour hasn’t actually changed. Similar shifts can be experienced, in reverse, by first increasing, then decreasing green. See the extremes by comparing the appearance of the number with background at full red (255, green = 0) to full green (255, red = 0). Similar effects can be seen for the other two colour pairs (red-blue and green-blue).