# Re: physics trick

From: Ifrit (cp005g@mail.rochester.edu)
Date: Mon Jan 22 2001 - 10:20:39 MST

Take the proportion of size of H to O and those are the percentage colors
straight out. Don't forget to factor in the white background as
well. Both canvases should be very close to the same color.

Verified with a crude representation, on paper, not many x's, h's or o's,
as was all I had time to do. If someone actually has canvases and wants
to try this...but at any rate they both looked the same to me.

Important notes to remember if trying this: Both must have the same
background, be at the same angle relative to the eye, have a centralized
light source so equal illumination.

It might also be good to do this through two cardboard tubes held up to
the eye so that one can only see the canvas' design pattern.

Another question though. Do the choice of colors matter? If one mixed
something such as red and green, or any two 'opposite' (don't remember the
word, like red-green, purple-yellow, blue-orange) the ability to
distinguish will extend much farther, and in theory the composite color
should be brown. But I doubt this will ever appear brown...

On Mon, 22 Jan 2001, denis bider wrote:

> Hello everyone,
>
> I'm not entirely sure whether this puzzle is on topic - it's probably more
> so than the guns debate I triggered, but anyway - here it is:
>
> Suppose we have two canvases, each 100m x 100m in size. We also have two
> LARGE buckets of paint; we shall call these color1 and color2.
>
> On the first canvas, we paint square tiles of alternating color, each square
> being 0.25m x 0.25m in size. I.e., the first square has color1, the second
> one has color2, then color1 again, and so on until we paint the whole
> canvas. After we're done, the canvas should look like a chessboard:
>
> HOHOHOHOHO
> OHOHOHOHOH
> HOHOHOHOHO
> OHOHOHOHOH
>
> On the second canvas, we paint a balanced mixture of color1 and color2:
>
> XXXXXXXXXX
> XXXXXXXXXX
> XXXXXXXXXX
> XXXXXXXXXX
>
> Then we hang both canvases on something large and remove ourselves far
> enough away not to see the individual square tiles on the first canvas. What
> is the perceived color of the first canvas? What is the perceived color of
> the second canvas? Are they the same?
>
> - denis
>
>

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