Information for pair0105:

Brightness of screen

This is from an experiment that has been performed to generate an example of a cause-effect relation
that is clearly unconfounded. Patches of size 3x3 pixel are randomly drawn from a fixed black and white image. The patch is then displayed
as an image of size about several centimeter. A photo diode is placed several centimeter away from the screen at a position where the light intensity is dominated by the patch. 
(More precisely, the light intensity is measured by the 
Adafruit TSL2591 High Dynamic Range Digital Light Sensor connected to an Arduino microcontroler. 
https://learn.adafruit.com/adafruit-tsl2591/wiring-and-test).
pair0101 is based on the same experimental setting, but there the `patches' have size 1 x 1 pixel. 

First column (x): pixel vector of grey values of the patch.

Second column (y): light intensity seen by a photo diode placed several centimeters away from the screen.  


The measurement has been performed by D. Janzing in August 2016.

ground truth x->y