black and white optical illusion
A weird and wonderfully effective optical illusion, created by digital media artist and software developer Øyvind Kolås as a visual experiment, works by tricking your brain into seeing a color image that's actually black and white. The illusion works because the brain automatically fills in information missing in images (and even moving images like video) to interpret the world around us.
Kolås calls the technique the "Color Assimilation Grid Illusion". It involves simply laying a grid of selectively colored lines over an original black-and-white image. He explains on his Patreon page:
An over-saturated coloured grid overlaid on a grayscale image causes the grayscale cells to be perceived as having colour. I came up with this illusion by experimenting with different patterns – and recently having worked on improvements for the saturation operation and being inspired by other illusions, and most recently David Novick color illusions in particular the ones like this Munker illusion with Tennis balls.
How It Works
Colors are different wavelengths of light. An object is whatever color you see it because it has reflected those particular wavelengths of light and absorb other wavelengths. For example, a blue bus reflects blue wavelengths and absorbs the remaining colors.
The human brain and eyes work together to see these colors, or wavelengths to be precise. These wavelengths of light travel to the eye, which works using photoreceptor cells called rods and cones. There are up to seven million cones which identify different wavelengths of light roughly corresponding to red, green and blue; and only 120 million rods which detect mainly black and white information. Next, the brain pieces together all of the information that the rods and cones collect which is how we see color. When it does this, it often fills in "missing" parts in order to interpret the world around us.
The 'Color Assimilation Grid Illusion' works because the brain is filling in the missing information thus turning the monochrome images into color. Bart Anderson, a vision scientist from the University of Sydney, explains to ScienceAlert what exactly is going on here when we look at these images:
The colour system is what vision scientists refer to as 'low pass', i.e., many of the receptive fields that code colour are quite large. So the grids get 'averaged' with the achromatic background, which then gets attributed to that part of the image.
Meaning that when we look at things, our brain kind of compresses visual information thus giving us an overall impression of what's there. Only if we stop to take the time to examine objects closely do we see them for what they really are. In this sense, a little bit of color could go a long way!
The artist explains how in this illusion, the reconstruction is happening in our eyes/mind – but it uses the same principle that Chroma Subsampling does, which is that luminance is a lot more important than the chroma for our visual perception.
The Experiments
The artist tried out a variety of different overlays. He used a grid of lines, dots, lines at differing angles across the original image, and even text to produce the illusion.
Kolås explains:
The raster of dots gives a nice analogy to half-toning as used in print, where colour assimilation aids the optical mixture of colours that already happens before our visual system gets involved.
He found that the grid works best. Although it also works quite well with lines, they need a tighter spacing than the grid.
Here are the original, and de-saturated / grayscale versions:
He also created a video that shows how the illusion doesn't require static images. Even full-motion video with the grid overlay is able to trick the brain into thinking it's seeing a color film.
black and white optical illusion
Source: https://www.intelligentliving.co/optical-illusion-black-white-color/
Posted by: comesbeamer.blogspot.com
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