Awesome I really enjoyed that. Except it’s not an illusion it’s a reality.

Light is such a beautiful and fascinating thing and we still can’t understand it 100% = exhibits properties of both waves and particles
This concept opens up many doors to creativity.

The same principle works with color, replace the luminance gradient with tones of color on a grid of RGB hue’s. what you will get is yellows that appear as orange, blues appearing as purples etc. the surrounding color affects the appearance of an object. A standard principle in art

Marco Tempest biggest trick in that clip was to make lie’s and deception appear as honest and good. ART is perception not deception, not impressed at all.
Get a LIFE Marko what you have is a LI.E.

Just my opinion.

Cute demonstration -- I wish Youtube would delete the clipped, distorted audio. It is annoying.

Something's really fishy about that. The two squares are the same color because the lighter one is in the shade while the darker one is receiving full illumination, not because they are actually the same color. In the same illumination they would NOT be the same color. So, when the sheet of paper is lifted from one and moved to the other it also moves to a different illumination level and should change brightness as it moves, but it doesn't. So that part is faked.

Kelly -- it's the shadow on the checkerboard that is faked.

Check out the lighting setup at 0:30 -- in fact the first half of the video is showing the lighting setup. The top of the checkerboard is evenly lit by the softbox overhead -- the shadow on the checkerboard itself is faked (part of the checkerboard image). Notice that the girl's hands never go into shadow as she reaches across to move the square.

Tim,

She has to reach into the shadow to get the square. So she does cross into the shadow with her hands.

Dave T2

Ah, what cynicism can arise... I thought it was pretty cool and agree that her hands do in fact cross over light to shadow all the way. Now, is there some alpha/green screen going on or other trick? Dunno. But so what, it's an intriguing clip. Sometimes things in life can be good-enough as-is.

It's an illusion that has been around quite a while.

Here's a link that discribes how it works: Checkershadow


Below is another YouTube video that makes the point (it evens uses the same music ;-)





Below is the image mentioned in the video:

That's one of the best optical illusions I've seen:




...Jerry

So in that case, the illusion wasn't "duplicated in real life".

I've never seen this illusion before, but I think there is no trickery in the video. Seems to me it can all be explained by arranging the lighting levels so that a "white" square in the shadow light has the same apparent brightness, to the camera, as a "black" square in the bright light. That would explain all I see. It's a very cool illusion, and I think anyone could duplicate it based on the setup shown in the video.

James

back in the day when I was a faculty member in the psych dept. at SMU, I saw the most amazing demo of color that I had ever seen. Based on the research of Edwin Land (Polaroid, etc.), I "saw" a full-color photo that was produced by one red light projected through a transparency and one blue light transmitted through a copy of the same transparency. Despite the fact that no green or yellow or other wavelengths were present - due to the fact that the source lights were carefully filtered to exclude those wavelengths - a full-color image appeared, with plenty of yellows, greens, etc.

Perhaps even more amazing, I saw a full-color image from two separate MONOCHROME transparencies, one of which was shot from the camera with a red filter, and the other with the red filter replaced with a blue filter; then the two B&W transparencies were projected through projectors that were filtered in the same filters as when they were shot. Result: full color - no color film needed.

See more at http://en.wikipedia.org/wiki/Retinex#Retinex_Theory

That's just one reason why I'm trying to improve my intuition - I'm no longer the strong believer in empiricism that I was back when I was an atheist, and I'm convinced that intuition is the stronger option (if we'd just spend as much effort to develop it that we've spent on the empirical/rational epistemology model).

Could be YouTube's compression, but when I take a screen grab of those tiles and use Gimp to compare the colors they are different shades.

Jasman, that doesn't explain why the square that is moved doesn't change shade when it enters and leaves the shadow.

Larry, i don't see anything about two-color lighting in that article. Everything described there uses three colors.

I'll also point out that there really isn't any such thing as color film. What we call color film is a sandwich of three layers of monochrome film, each sensitive to only one of the primary colors and then dyed with a color filter. In fact, the early technicolor process used three separate rolls of B&W film, three cameras, and three projectors.

The whole shadow thing puzzles me. On the wide shots you see the light that causes the shadow, but maybe on the closeups the lights are changed and the shadow is just painted on.

Look again. The illusion that it doesn't change shade while moving is fostered by the surrounding squares (context). If all those squares were obliterated, it would be clear as day I think.

Pause the video when the square is passing through the edge between shadow and light. I clearly see two levels of illumination on the moving square. By this I conclude the lighting is real, and the squares are a fixed physical shade of grey. I think the illusion is so good, in part, because that fleeting movement information is over-ridden by the stronger and longer static image of the new location.

James

> "If nothing else, it's an interesting use of lighting."

If nothing else, it should prove to everyone that anyone who thinks they can use their eyes alone to color calibrate their video monitor without a hardware device like the Spyder3 is kidding themselves!!! ;-)

~jr

We had our house painted last year. A sample patch of brown color was painted on the white wall of the back of our house. The patch was about 3 feet square, and it looked medium-dark brown. we liked the color, and had the painter go ahead. When he was finished, the whole house looked a light beige. All because the contrast with the bright white was now gone. Convinced us forever about the tricks of light, color and contrast.
(fortunately, the light beige doesn't look bad.)

A guy at work got his house painted pink for the same reason.

@ Chienworks:
"Larry, i don't see anything about two-color lighting in that article. Everything described there uses three colors.

I'll also point out that there really isn't any such thing as color film. What we call color film is a sandwich of three layers of monochrome film, each sensitive to only one of the primary colors and then dyed with a color filter. In fact, the early technicolor process used three separate rolls of B&W film, three cameras, and three projectors."
---------------
Totally right. But that's the point: The THREE cameras captured all the info traditionally thought to be needed by our THREE color receptors on the retina. In contrast, Land was able to make flawless "3"-color images with only TWO wavelengths. Actually, almost any two wavelengths work - no need to use widely-separated wavelengths such as red and blue.

Regarding the Wiki article: Yup; not the best wiki article, IMO. I found a much better one:

http://www.greatreality.com/Color2Color.htm

This article does an excellent job of describing the two-wavelength phenomenon.

@ Chienworks:
"ll also point out that there really isn't any such thing as color film. "

May I point out that you then went on to describe what is known as " Color film " ?

Printing:

" A sandwich of three layers of monochrome film, each sensitive to only one of the primary colors and then dyed with a color filter. "

....on those little boxes would not be very practical ..

"what is known as"

Exactly.