A different kind of IotD today, suggested by axlrosen. Look at this image up close, and you see an angry man and a neutral woman. "defocus" or pull back, and the face on the left becomes more neutral and female while the face on the right becomes more angry and male
From
this page of optical illusions at MIT, the official caption:
On a close-up view, you can see on the left face, an angry man and on the right face, a woman with a neutral facial emotion. But further back, the faces change expression and even genders! if you squint, blink, or defocus, an angry man should substitute for the face of the woman and the left angry face should not be angry anymore.
This impressive illusion created by Dr. Aude Oliva and Dr. Philippe Schyns, illustrates the ability of the visual system to separate information coming from different spatial frequency channels. In the right image, high Spatial Frequencies (HSF) represent a woman w69, 243-ith a neutral facial expression, mixed with the low spatial frequency information from the face of an angry man.