fechner color effect

[Harry Dalek]

An effect i always found interesting and wondered if there were a way a displaying colour with out colour wheels or colour lights .

While viewing a 16mm projectors white lamp light and adjusting the shutter speed you start to see colours like a mechanical prism.

Looking up this effect its called fechner color effect.

Makes me wonder if you had a system of 3 white lights and 3 shutter wheels running at different speeds could you make a colour tv system if you mixed the 3 strobed lights.

Any case an interesting effect.

http://en.wikipedia.org/wiki/Fechner_color

Also looking at this site different effect using different colours http://mathworld.wolfram.com/BenhamsWheel.html

[Harry Dalek]

Have a another think about it strobing white 3 white luxeons and modulating them same time ...in pwm system ? might do the same thing.
Back to doing the dishes

[DrZarkov]

A nightmare for cameramen in the age of CRTs were suits with a fishbone pattern. When they were moving and the distance to the camera was right, you had those strange colour-effects. I remember a certain old black and white thriller from the 1950s. When I saw it on TV in the 1980s, the police inspector had sometimes rainbow colours in his jacket. It does not work with modern TFT HDTV sets.

[Steve Anderson]

Fine patterns on clothing and other closely-spaced near vertical objects were avoided as much as possible, the effect is called cross-colour. It comes about where the luminance frequency is high enough that it confuses the simpler PAL and NTSC decoders used in most TVs.

In the days of test-cards the higher frequency part of the frequency gratings often produced the same effect.

I used to have a JVC S-VHS machine and this had a comb filter in the decoder, YUV into the TV produced no off-air cross-colour. These filters were/are generally used in the larger and more expensive TV products.

Often this effect went unnoticed in the studio as the banks of monitors used in the gallery were professional with comb filter decoders. Propped up in the corner was usually a domestic-grade TV known not to have a comb-filter decoder for checking this wasn't occurring.

Unfortunately directors/producers can't control what clothing a guest may be wearing, by the time they arrive at the studio it's too late. The answer was for the cameraman to re-frame the shot and/or zoom in or out slightly, thereby changing the frequency of the interference.

Steve A.

As an analogue stop-gap Super-PAL or PAL+ (I can't exactly recall the proper name) was dreamed up for this and several other reasons. The sub-carrier was shifted to twice the normal frequency at 8.86MHz. This meant that luminance frequencies around 4.4MHz didn't produce cross-colour, But its life was short and it didn't really catch on.

Later..In fact it was called Extended PAL and was more complex than just shifting the sub-carrier frequency. It was developed by the BBC for DTH satellite transmission in 1982.

[Lowtone]

A nightmare for cameramen in the age of CRTs were suits with a fishbone pattern. When they were moving and the distance to the camera was right, you had those strange colour-effects. I remember a certain old black and white thriller from the 1950s. When I saw it on TV in the 1980s, the police inspector had sometimes rainbow colours in his jacket. It does not work with modern TFT HDTV sets.

Ahaha The first time i had a camcorder i wanted to film a kind of parody of tv news bulletin, and i've chosen to dress like this in order to produce the same effect. Sadly the pattern was a bit too large for this

There also were 100㎐ tube TV who has the ability to reduce this effect.

[Rydepier]

I used to have a Tandy CoCo 64 with an upgraded 80 line black and white video card that had a video mode that allowed this kind of colour 'trick'. At the time, in the eighties, it did not seem at all strange to convert a perfectly good colour display to black and white then struggle to get it to produce a colour 'effect'.

[seanpualion]

I have just joined and I hope I will learn a lot of new information here.
I admire the valuable information you offered in your article. Excellent submission very good post.Keep posting thumbs up.

[Harry Dalek]

I have just joined and I hope I will learn a lot of new information here.
I admire the valuable information you offered in your article. Excellent submission very good post.Keep posting thumbs up.

Watch out you may get addicted to this hobby
Read the old postings from every body its a gold mine of information.
A big welcome from me .