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Excellent. This is up there with the best.

Digital Cinema for Dummies.

"The future is already here -- it's just not very evenly distributed" William Gibson

by ChrisCook (cojockathotmaildotcom) on Fri Apr 23rd, 2010 at 07:01:53 PM EST
[ Parent ]
Colour is weird. One of my favourite illusions:

The 'yellow' and 'brown' center tiles are the same colour.

There's also Adelson's checker illusion:

A & B are the same colour.

by ThatBritGuy (thatbritguy (at) googlemail.com) on Fri Apr 23rd, 2010 at 07:35:49 PM EST
[ Parent ]
Thanks Chris. I have seen variations on the top one, but not that exact one before.

The proof for the lower one, Adelson's checker illusion, is at this site: Checkershadow Illusion

Here is a number of illusions called: Lightness Demonstrations.

For a site of color-centric illusions: Illusion and color perception-Akiyoshi Kitaoka

This stuff is so fun, that I could spend a morning on it.

Motion, Form, and Mid-Level Vision: A Tutorial

There is also the illusion of using space when one presumes a flat object:
First
Second

If you see a proof of your top submission, please pass it on.

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Sat Apr 24th, 2010 at 04:35:15 AM EST
[ Parent ]
The proof for the lower one, Adelson's checker illusion, is at this site: Checkershadow Illusion

For some reason or other, I don't get the "proof". It convinces me that either the original image or the proof is an optical illusion, but I can't decide which. Using an image editor and moving a small piece from one square of the image to the other is what worked for me.

by gk (gk (gk quattro due due sette @gmail.com)) on Sun Apr 25th, 2010 at 09:24:39 AM EST
[ Parent ]
Thanks Chris. Being a Dummy myself gives me a unique qualification for being able to present the data that has clawed its way into my mind.

Erratum: I need to correct one thing in the comment (not the article itself.) As I noted in its intro, it was extemporaneous and not fact checked.

There is an assertion that I made which I can't back up. It concerns the statement:
"... while the receptors that deal with levels of brightness are called the rods."

I don't think that this is entirely true or best describes the function of the rods if it is true. It implies that the cones are not able to capture brightness detail without the rods, which I don't think is correct.

On the other hand, the rods are more sensitive to light and dark, whereas the cones do not function well as darkness increases until the point that they don't function at all. Further, the rods don't get triggered by red light at all, which will give the sunset phenomena of a red rose going dark while the green leaves around it glow more green shades.

Quickly searching through some source material doesn't provide the exact right answer to better describe the function of the rods. My new plan is to refine this long comment above into a "Part 0" of the series. When I get that detail correct for that section, I'll make it known.

Never underestimate their intelligence, always underestimate their knowledge.

Frank Delaney ~ Ireland

by siegestate (siegestate or beyondwarispeace.com) on Sat Apr 24th, 2010 at 03:57:01 AM EST
[ Parent ]
Wikipedia: Photoreceptor cells

You can't be me, I'm taken
by Sven Triloqvist on Sat Apr 24th, 2010 at 04:11:31 AM EST
[ Parent ]

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