How to make a Black and White television show color

In summary, the speakers discuss a past experience where they saw a color image on a black and white television using a strobing technique. They also mention a similar demo shown in the UK and a scam from the 60s claiming to turn a B&W TV into color. They discuss the principles behind this technique and its limitations for dynamic shots. They also mention articles and experiments using spinning discs to create a color illusion on B&W screens.
  • #1
Ivan Seeking
Staff Emeritus
Science Advisor
Gold Member
8,142
1,755
Something happened that reminded me of this tonight, and I think I have finally made sense of something seen as a kid. For some odd reason it just hit me. When I was fairly young and living in the Los Angeles area, there was a test done one night on a local TV channel that was supposed to produce a color picture on the black and white TVs commonly in use. And I can recall seeing some color; I think mostly green. From time to time I have thought about this and wondered what it was that I saw. In fact at times I have doubted the memory as it didn't make any sense, but I can remember the event very clearly. Tonight it occurred to me what they were probably up to. I bet that they were strobing the white to produce a false color image, as is done with alternating black and white dots on a rotating wheel [I don't recall the name of the effect]. The idea is that each pixel on the screen would be strobed at the frequency required to produce the desired color for that dot.

Does this make sense? I'm not sure what the strobe rate is that produces the false color effect, or if this was doable on B&W televisions, but it is the only thing that has even threatened to make any sense here. Is there any other way that one can imagine producing color on a B&W screen?
 
Last edited:
Physics news on Phys.org
  • #2
I can remember seeing a similar demo in the UK in about 1970 - most likely on the "Tommorow's World" weekly science program. I think they said it was done by modulating the intensity, but I don't remember any more details.

It was a test image with a few large areas of different colours (which were very faint), not an attempt to show a "realistic" moving colour image.

If you want to experiment, all you need is a PC and some free software that can generate a movie from frame-by-frame images.
 
  • #3
I haven't heard of that one, but I remember a scam from back in the 60's wherein some dip was selling a way to turn your B&W set into a colour one. Nobody that I knew fell for it, so I never saw one and don't remember the exact details. It was some sort of plastic film that you stuck over the screen. I'm not sure if it was a diffraction grating system or what, but it gave a sort of pale 'aura' around some images. Hardly hi-def.
 
  • #4
Ivan Seeking said:
Tonight it occurred to me what they were probably up to. I bet that they were strobing the white to produce a false color image,
Yes it can be done, the problem is that it only works for farily static shots since you need to modulate several fields to get a colour so it's not good for car chases and the effect only works for a small proportion of people.
It's a similair principle to the moire fringes from presenter's checked jackets producing an illusion of colour on b+w TVs.
 
  • #5
It could make an interesting science fair [or lab] project that might amaze some of the judges, esp until the principles are explained: Make a carefully coordinated [perhaps a minimum of motion?] B&W cartoon that is viewed in color on a B&W TV.

Did anyone spot a link giving the required strobe rate for various colors, or the name of the false color effect involved?
 
Last edited:
  • #6
i remember when Popular Science (or maybe it was Popular Electronics) had an article about this. i was in high school at the time. they had printed on the page a disk you could cut out and spin on something (i think i mounted a 3/16" bolt to the center of the disk and spun it on my mom's hand held electric mixer which had variable speed). the disk was divided into 6 equal sized sectors (just like pie-slices). three adjacent sectors were all black. the three other (adjacent) sectors were white with two stripes that were part of two concentric circles but only for the angles for that sector. the radius of each stripe was different.

when you spun it around, the two stripes (for each sectors) spun around and looked like a flickering circle. at some speed, the circles kinda "lit up" with a color appearance. the two inner circles (from stripes in one sector next to the black half) were one one of either cyan, magenta, or yellow (but i don't remember the order), the middle two (from the middle sector) where another of those colors and the outer two were the remaining color. we could reverse the rotation by putting the post in the other spindle of the hand mixer and the colors of the inner and outer pairs of circles were swapped.

we had a B&W video tape recorder at school (this is before the days of VHS or Beta, it was reel-to-reel) and i used the camera and monitor to try to get this to work over the video, but it was not successful. at the rotational speed that it lit up in color perceptually, it looked like flickering crap on the TV monitor. i think i could slow the thing down 10 Hz and sort of sync it with the TV verticla scan (it moved one sector, 60o each vertical field scan) but that was not the right speed to get the neuro-perceptual effect.

since, i have seen a cheap wooden top that had a similar pattern (but i think it had four sectors in the white half). i think it works best in natural white light that isn't synced to the AC power source or anything. spin the top fast, and as it slows down, eventually it hits the speed that the gray flickering lines become a light hue of color. neat optical illusion.
 

1. How does a black and white television show become color?

Black and white television shows can become color through a process called colorization. This involves digitally adding color to each frame of the original black and white footage.

2. Can any black and white television show be made into color?

Technically, any black and white television show can be colorized, but the quality of the final product will depend on factors such as the quality of the original footage and the skill of the colorization process.

3. Is colorization a new technology?

No, colorization has been around since the early days of film and television. However, advancements in digital technology have made the process more efficient and accurate.

4. How long does it take to colorize a black and white television show?

The time it takes to colorize a black and white television show can vary depending on the length and complexity of the footage. It can take anywhere from a few weeks to several months to complete the process.

5. Can colorization affect the authenticity of the original show?

Some argue that colorization can detract from the authenticity of the original black and white footage, while others see it as a way to enhance the viewing experience. Ultimately, it is a matter of personal preference.

Similar threads

  • Classical Physics
Replies
21
Views
870
  • Programming and Computer Science
Replies
1
Views
1K
  • Other Physics Topics
Replies
13
Views
7K
Replies
4
Views
807
  • Special and General Relativity
Replies
20
Views
1K
  • Materials and Chemical Engineering
Replies
12
Views
2K
  • Other Physics Topics
Replies
7
Views
884
  • Other Physics Topics
Replies
9
Views
1K
  • Special and General Relativity
Replies
7
Views
1K
Back
Top