4 ms·
Optical illusions reveal that we have more than three axes of color perception. The first gif and the last photo are examples of this, and the renaissance artis
by sillysaurus3 9y ago
Optical illusions reveal that we have more than three axes of color perception. The first gif and the last photo are examples of this, and the renaissance artists had a firm appreciation of it. (See DaVinci's journals, specifically the chapters on color.)
Part of the reason I want to put together this series is to rekindle this knowledge. It seems very much "lost": your comment represents the status quo of color science, but if you were an ambitious artist in 1450, you'd run experiments and determine that much of what we take as fact is actually quite a lot more complicated in practice.
The eye, and especially our perception of colors, is so complicated that entire tomes barely scratch the surface. And Munsell's discoveries were only made in 1900, barely over a hundred years ago. There's still a lot more to discover.
To be clear: it's true that our three receptors imply three axes of color perception. But when you assemble an image as a whole, the entire portrait results in an experience quite different than any individual color.
EDIT: That the perception of color is influenced by surrounding colors is true, but that this adds a "fourth channel" is [citation needed].
One of the most important aspects of color science is that you have to be willing to believe the possibility that some strange ideas are true.
In this case, I can dispel that illusion, but only if you're open minded to it:
Consider a painting. Why choose a certain shade of yellow? To produce an effect.
The above images demonstrate that where you put that shade of yellow causes a very different effect.
Now, if you accept as an axiom that the only reason to choose a color is to produce an effect, then that means all three primary colors (red, green, blue) are different axes in your ability to cause an effect. But the fact that the arrangement of colors causes different effects means that the spatial arrangement is a fourth "lever" that you can use to change the experience. That implies it's accurate to call this phenomenon a fourth channel.
(I'd post this edit as a reply, but HN isn't having it right now.)
One interesting area of science to investigate is the frequency spectrum of natural images. Our brains are tuned to see certain frequencies more than others, e.g. blades of grass. And the reason colors produce different effects depending on where they are in relation to each other is to help us resolve different shapes in an image.
http://web.mit.edu/torralba/www/ne3302.pdf http://web.mit.edu/torralba/www/ne3302.pdf
https://www.cs.cmu.edu/~efros/courses/LBMV07/presentations/0208Gist.pdf https://www.cs.cmu.edu/~efros/courses/LBMV07/presentations/0...
- tbabb 9y agoThe statement I take objection to is this: > The fact that colors influence colors around them means that there are far more than 256^3 viewable colors: the spatial axis is like a fourth channel. That the perception of color is influenced by surrounding colors is true, but that this adds a "fourth channel" is [citation needed].
- just2n 9y agoI'm not sure I buy that it means there are more absolute viewable colors there, but rather there are merely different interpretations of the same colors. We do have fairly strong confirmation that our brain doesn't interpret color absolutely but can adjust based on luminescence (see: all examples of shadow illusions) and patterns (see: https://www.youtube.com/watch?v=mf5otGNbkuc https://www.youtube.com/watch?v=mf5otGNbkuc), perhaps that's what is meant by a "fourth channel"?
- psyc 9y agoI’ve referred to DaVinci as the father of CG, based on his formalizing the perspective projection. This bit about color adds to my thesis.
- roywiggins 9y agoThe simplest example of this is that in a watercolor class I was told to make shadows bluer than the object, not just blacker. And indeed it looks much more natural than a black shadow, and I think it's this effect of juxtaposing colors.
- tbabb 9y agoThe sky is blue and the sun is yellow. Subtract the sun and you are left with only blue light from the sky. ...which explains why indoors, shadows /do/ tend to be colorless: http://www.camilleprzewodek.com/uploads/1/5/9/2/15923552/6393647_orig.jpg http://www.camilleprzewodek.com/uploads/1/5/9/2/15923552/639...
- dkersten 9y agoIf you have a one dimensional line, you can use a 1 dimensional value x to represent its position. If you add a second input, y, and instead say that your position on the line is x+y, the line is still one dimensional, even though y changes how the value x is perceived. (Because the point x,y can still be represented with a single value z where z=x+y) There are three colour receptors, so colour is 3 dimensional to us. That the surrounding context shifts where that 3d point falls in the colour space doesn't create more colours, it just shifts the perceived colour around the colour space. In your strawberry example, the gray and red already exist in the 3d colour space. The context did not create these, it just shifted our perception a little off the point in the colour space that the pixel value alone would have placed it. Similarly, if I wear sunglasses, the darkness doesn't add another dimension, it just shifts all the values a bit in a direction that makes them darker. Note: I'm not actually arguing that there are only 3 dimensions of colour (although our three receptors would suggest it), as I don't know enough about it. I'm just pointing out a flaw in your logic.