3D Chalk Drawing of Mona Lisa Made by my favorite Artist Julian Beever.
Enjoy!!
Stare steadily at the dot in the heart for 30 seconds, then look at a piece of white paper. A faint Red heart surrounded by a bluish outline should mysteriously appear on the paper.
This is called an aftereffect. Staring at the heart overstimulates your eyes' photoreceptors, which are what absorb the light that stimulates vision. So even after you look away from the image, your brain is still receiving messages about it. What you end up seeing are called complementary colors. Red and blue are complementary colors of green and yellow.
- Al Seckel
When sets of disks with tangential greylevel gradients are arranged in concentric circles (see image above, most observers perceive these disks moving around the centre,. This motion illusion is enhanced for large-scale and bright images and depends to a large extent to dynamic changes in the stimulus such as elicited by involuntary eye movements or blinks – fixating the centre of the pattern does abolish the illusion, whereas scanning the picture the motion sensation. A reliably effective version of this illusion, which does not require eye movements (i.e. persists when observers fixate the target in the centre of the image), can be generated by modulating the background luminance of the array of disks . This stimulus offers the opportunity of studying this motion illusion – the percept of spinning disks in the absence of any physical displacement – in a highly controlled manner in psychophysical and physiological experiments, because it is not depending on involuntary eye movements or eye blinks.
This photograph taken in Bad Langensalza, Germany shows one of many pillars placed around a fountain. The illusion here is that the pillar can either appear to be hollow or to have a pyramid on the top depending on which way you look at it. The shadow on the right gives it away slightly but its still quite convincing.
