So you thought bees had trouble with colours!

[Monsieur Abeille]

What’s the difference in colour between box A and box B?



Answer: None: they are both the same shade of grey (see http://www.scientificamerican.com/slideshow.cfm?id=169-best-illusions)

If you doubt it (as I did) print it out and compare

 

[Queens59]

Retires whimpering into the nearest corner.....

 

[Saturn]

Huh, interesting. Confirmed in Photoshop (RGB 139, 139, 139 in both squares).

 

[victor meldrew]

Can't help thinking it's to do with true colour v pigmentation which of course reflects colour rather than emits colour , rainbow (coloured )pigments mixed absorb all light so appear black whereas all colours mixed make white light ??

John Wilkinson

 

[hedgerow pete]

read, printed, now dribbling in corner banging head against wall

 

[PaleoPerson]

Great way to freak out a teenager.

Printed in black and white and then told her to cut out the two squares and compare them, then put them back and the reverse them.

I am not sure I can continue ignoring the temper tantrums though

 

[Skyhook]

Retires whimpering into the nearest corner.....

 

[oliver90owner]

Deleted. Sorry, wrong thread!

Regards, RAB

 

[barratt_sab]

The BBC website has an article today with some interesting illusions:

http://www.bbc.co.uk/news/magazine-11553099

I particularly liked the Cube Illusion. There is a Horizon program "Seeing is Believing" on BBC2 tonight at 9pm.

 

[Repwoc]

Can't help thinking it's to do with true colour v pigmentation which of course reflects colour rather than emits colour , rainbow (coloured )pigments mixed absorb all light so appear black whereas all colours mixed make white light ??

John Wilkinson

That's Additive vs Subtractive colour.

With subtractive, you start with white light (daylight or fluorescent tube) which broadly comprises all visible wavelengths. Dyes/pigments in a substrate then selectively absorb parts of the visible spectrum and reflect the rest, so if eg blue-green (cyan) is absorbed and red is reflected, the substrate appears red. As stated, if you mix the three primaries all wavelengths will be absorbed making black.

With additive, you start with black (no light) and add coloured light (eg with red, green & blue phosphor dots in a tv screen) in proportion to achieve the desired colour. If the three primaries are mixed in equal proportion, the result is white.

Never heard it referred as true colour or pigmentation though.

 

[victor meldrew]

Never heard it referred as true colour or pigmentation though.

My terminology I'm afraid

John Wilkinson