Google

Category
 
Recent Entries
 
Archives
 
Links
 
Visitors

You have 1539279 hits.

 
Latest Comments


 
Posted By Peter Bentley
Today I was doing research for another book idea, perhaps a sequel to The Undercover Scientist. I was checking 3D red-cyan glasses just to provide an example of how some materials absorb certain frequencies of light. To my surprise I discovered that more than one web site seemed to be giving a very misleading explanation of how 3D glasses work, giving a picture that shows red emerging from a blue filter, and blue emerging through a red filter. So I sent an email to let them know... and this nice little debate followed:

Please note that the image from "how stuff works" explaining how the 3D glasses work is incorrect. A red tint only lets red light through and a blue tint only lets blue light through.

Thanks for your concern. The arrows in the image represent the image that each eye views.

Blue lens filters the blue and only allows that eye to see red image and the red filters the red and only allows that eye to see the blue image.

That's not right. Blue filters let blue light through, and will block red images. Red filters only let red light through. That's why the light appears blue or red through them - they block all frequencies other than their colour.

If you don't believe me - try it. We have a red laser here that is blocked by a blue filter, but passes through a red filter - as you would expect. The diagram is therefore incorrect.

So explain How the decoder (Red) lens works: With your idea when looking through red lens it would only see red image. Wrong! Red filter blocks everything that is red in the image and only allows the blue hidden message to be reveled. Or How the Wobble viewer works: Blue strip of film lets you see red image and red strip sees the blue image. Works the same for 3d Anaglyph.

Test it yourself: Type the word red in red and the word blue in blue on a white screen, look through the red lens, the only word you will see is the word blue.

By the way: You are the only one to complain in the 5 years it has been up. I did not create image, but copied it from another site.

OK, I did your experiment. Red written in red, blue written in blue. I look through a red filter and I see the word blue more clearly. This is because the blue text is now darker, the red text remains unaffected, and the white background has been filtered so that only the red frequency comes through. The red filter blocks the blue light, making the blue appear black. It lets the red light through unchanged.

So I repeat - a red filter only lets red light through, including the red of the text and the red in the white background. It does not let the blue light through, which is why it appears black. Same applies in reverse for the blue filter.

You are confusing light and dark here. As for why no-one else has complained... I couldn't say. But I am a scientist, based in University College London :)

Okay. I accept that. When ever I get a chance I will fix the image by changing the arrows (red to blue and the blue to red). I have not updated in 2 years and I am currently working on 80 2d to 3d images for one project due in 2 weeks time. Doesn't give me time to keep up with web page. (Just 1 artist for - Glasses design, 2d to 3d conversions, custom die -cut, lens effects, in house promotion, and web.)

Not your fault, William. I know the originator was howstuffworks.com. It's good of you to be thoughtful enough to care.

Good luck with the 3D work, and thanks for a nice discussion.

And this is the incorrect diagram that seems to be confusing so many people. As I hope you can work out, only blue arrows should emerge from the blue filter and red arrows from the red filter. Watch what you believe!


 
3 Comment(s):
shawn said...
Hi sir 、 How are you?This is Shawn from Getteks company 、I am sorry to write this email to you without your permission 、we are a professional 3d glass factory 、hope any item can be interesting of you 、bellow is the information of our company. it’s my pleasure if you can visit it in your free time .thanks . have a good day ! Best Regards! Shawn Xiao Shenzhen Getteks Electronics Co.,Ltd. ******************************************************************************* Tel: 0086-755-27515171 Fax: 0086-755-27321887 Factory Add: Building 7 Tangwei Village Fuyong Town Bao'an District Shenzhen 518103 China MSN: getteks_04@hotmail.com Skype: getteks_04 Email: sale.04@getteks.com Website: www.getteks.com
May 11, 2010 04:29:36
 
Phil said...
Just read my previous comment again and spotted a couple of typing mistakes. In case of any confusion it should read like this: Interesting stuff, thanks for posting this. I was messing around with some glasses that have two red lenses and I just wanted to understand what I was seeing, which is how I ended up here. I think it's also worth noting the part the brain plays in the interpretation of the image, though. Before I read your article I was looking at red text on a white background through the glasses and I could hardly read the text. I now understand that this is because only the red frequency of the white was getting through to my eye, thus I was seeing red on red. But my brain seems to tell me that white things still appear white. Now that I know different, if I concentrate, I can recognize that they are in fact red but somehow my brain tells me they're white. This reinforced my initial belief that the red was being filtered out, so that the red text appeared white and I was seeing white on white, thus making it hard to read. The brain and eyes are truly amazing things but tricking them is fun!
November 6, 2008 15:18:24
 
Phil said...
Interesting stuff, thanks for posting this. I was messing around with some glasses that have two red lenses and I just wanted to understand what I was seeing, which is how I ended up here. I think it's also worth noting the part the brain plays in the interpretation of the image, though. Before I read your article I was looking at red text on a white background through the glasses and I could hardly read the text. I know understand that this is because on the red frequency of the white was getting through to my eye, thus I was seeing red on red. But my brain seems to tell me that white things still appear white. Now that I know different, if I concentrate, I can recognize that they are in fact red but somehow my brain tells me they're white. This reinforced my initial belief that the red was being filtered out, so that the red text appeared white and I was seeing white on white, thus making it hard to read. The brain and eyes are truly amazing things but tricking them is fun!
November 6, 2008 15:12:11
 
Leave a Comment:
Name: * Email: *
Home Page URL:
Comment: *
   char left.

re-generate
Enter the text shown in the image on the left: *
 Remember Me?
* fields are requried