Comments on: Violet is not Purple: Is digital imaging broken?

By: p e d morgan

p e d morgan — Mon, 23 Feb 2009 10:42:46 +0000

Here is the web page, that I mentioned above, showing the secondary red absorbtion in the short wave region by the blue.

http://photo.net/learn/optics/edscott/vis00010

I would appreciate knowing of even more informative sources – thank you.

By: p e d morgan

p e d morgan — Mon, 23 Feb 2009 09:58:15 +0000

Correction: I note in the above that I made a mistake “Why does violet look like blue” should have been “Why does violet look like purple”.

By: p e d morgan

p e d morgan — Sun, 22 Feb 2009 10:00:03 +0000

The eye’s red receptor has a secondary absorbtion/response at short wavelengths in the farther indigo overlapping the blue receptor. The brain interprets naturally this as the mix of red and blue i.e. violet in this case, and so it looks like purple to the brain.

This is not easy to find on the web – I will post when I find the page again on a computer that does pdfs.

Most pages about color are mistaken in this regard (as are essentially all school teachers and people that believe that the color circle is a physical reality – it is a brain reality!). I use the “question”? “Why does violet look like blue” in my university course on “innovation and creativity” as an example of the “unasked question” that leads to scientific progress when it is finally asked.

By: pck

pck — Sat, 02 Sep 2006 05:36:24 +0000

Just an update to this, some Swiss researchers are claiming to have a possible solution involving electronically-driven diffraction gratings: New Tech for Hyper Color TV

By: Mark Tranchant

Mark Tranchant — Thu, 08 Jun 2006 13:10:26 +0000

A fine article. Your monitor approximates the sRGB colour space, which contains a mere 35% of the eye’s gamut. That’s equally shocking.

Dammit, your captchas are hard!

By: Cullen Jennings

Cullen Jennings — Mon, 02 May 2005 13:59:47 +0000

Interesting.

You have too much time on your hands but few extra things to through in your model …. Humans have 3 color receptors – you would think this would result in needing to describe color in a 3 dimensional axis plus of course the overall brightness – it does not. Somewhere in our brain, (not in the eye or optic nerve) these 3 axis get mapped to a perceptions with only has two degrees of freedom. Weird.

CCD and CMOS sensors are sensitive into infrared band so manufactures need to put in place filters that block this and causes weird effects. The human eye allows almost no ultraviolet light to pass – actually some operations remove this filter which allows people to see wonderful colors on plants and such for about 2 weeks till the receptors burn up. Rat’s on the other hand can see into ultraviolet pretty well.

There are lots of “colors” that are impossible to model on screen or standard printing – take any florescent color for example.