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Show HN: Rainbow – an attempt to display colour on a B&W monitor

anfractuosity.com

51–60 of 61 posts

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#51
post #21

Earlier quoted context omitted.

Wikipedia has it animated, too EDIT: warning! strobing! https://en.m.wikipedia.org/wiki/Benham%27s_top#/media/File%3...

When I look at that animation, I see brown bands. My girlfriend sees dark blue. Why?

I see brown too. Are you and your girlfriend using the same device?

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#52
post #39

An aside: I saw "Up" (the movie excerpted in the demo video) years ago, but I never stopped and thought about the physics until today. The house would have started rising as soon as sufficient balloons were inflated inside the house. Releasing the balloons doesn't magically start making them buoyant-- they're already buoyant when they're inside the house.

The balloons are under a tarp behind the house :)

Such a strong tarp!

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#53
post #27

Earlier quoted context omitted.

The trick is because the shade of grey DOES have chroma. You can't just apply any autochrome panel to the image (unlike what the OP is trying to do with Rainbow), instead, the negative is generated using the chrominance filter Imagine that each grain is blocking a 'pixel' of the negative. For simplicity of this explanation, I'll pretend the grains are red, green, and blue. If there's a blue grain, only blue light can…

Does it mean the filter has to very very precisely aligned when booth shooting and printing from the negative? I may be daft, and your explanation sounds reasonable but I still feel "magic + potato starch" :-D

The filter is part of the photographic plate, and the plate is developed directly into a positive. So there's no alignment issue.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#54

Earlier quoted context omitted.

When I look at that animation, I see brown bands. My girlfriend sees dark blue. Why?

I see brown too. Are you and your girlfriend using the same device?

I see brown. My wife and 13-yr-old son both see green, blue, and pink. Same iPhone, same time.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#55
post #21

Earlier quoted context omitted.

Wikipedia has it animated, too EDIT: warning! strobing! https://en.m.wikipedia.org/wiki/Benham%27s_top#/media/File%3...

Does anyone have an explanation of what I should be seeing here? I've been staring at it for a while (both full-screen and in the article), and I haven't noticed anything other than black and white.

In the spinning animation, the black bands in the white parts quickly turn another colour (brown for me, apparently blue or other colours for others) while the image is spinning.

The effect is much reduced if I tap on the image to make it full screen on mobile. The larger size seems to reduce the velocity of the spin, which seems to be an essential part of it. Could this be the reason you don't see it, are you perhaps on a low performance device for eg.?

Just for the sake of completion, the effect is incomplete for me - the outer black bands are always brown, but the inner two switch between black and brown. The middle one is more often black than brown, but it seems when that one's brown, the innermost one instead turns black.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#56
post #12

Very neat, the outcome probably isn't what you were hoping for, but it has a beautiful and ethereal quality to it. It's like an art piece. From the photos and video, only a small section of the screen has colour. Does that change as you move around, or is the coloured section static? Off topic, but the visual effect seen here is a lot like how my memories and dreams feel; only the thing I'm currently focussing on has…

Yeah I would like to improve the effect. I think the main colour region seems to stay the same. I'm wondering if I can get acetate that's ever so slightly adhesive, so it sticks better to the monitor, which I'm wondering might help the colours show better all over.

Also curious to know if you can get slightly better color spread by looking at it from far away; I assumed the misaligned light or distortion through the glass might be enough to throw things off if you're working with tolerances as small as it looks.

Or, maybe the electron beam scatters more as it's deflected to hit the the outer pixels, possibly giving you a signal too muddy for your magic potato pixels to work with. (these are obviously just vague guesses, I didn't even know this was possible before today)

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#57
post #50

I had no idea B&W LCD monitors even existed, looks like they are primarily marketed for medical imaging purposes, curious what advantage they have over displaying grey-scale images on a good color monitor. I'm guessing by the sub-pixels it is made from mostly the same panel as a color model.

I perused Ezio's website, and found three B&W monitors they currently sell, their "GX" series. Looking at the specs, the thing that stands out to me is that they're really bright: 1,200 cd/m^2 for the GX240 and GX340, and a whopping 2,500 cd/m^2 for the GX560 ! I bet these monitors are brighter than equivalently-backlit color displays from not having a Bayer filter in front. Speculations on why medical monitors might…

It reminds me of back in the 68k Mac days you you could set your screen to 256 colors or thousands of colors or thousands of greys, where you had to choose a tradeoff of resolution and the greyscale mode was primarily for desktop publishing applications ah QuarkXPress and PageMaker..

From their website --

> 10-Bit Simultaneous Grayscale Display

> 10-bit (1,024 tones) simultaneous grayscale display extends grayscale fidelity to the boundaries of human visual perception abilities and helps radiologists discern the finest nuances within an image.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#58
I bet you could get a lot better color if you used the screen itself to generate the bayer pattern on film rather than printing it with a printer.

Get some large format color negative film and thin cyan, magenta, and yellow filters. Put a cyan filter on the LCD, followed by the film on top. In a darkroom, light up the "red" pixels and to expose that part of the film. Repeat with the magenta filter and "green" pixels, and finally the yellow filter and "blue" pixels. Develop the film and reattach to the LCD.

This is kind of how the shadow mask was made in color CRT monitors. A photographic process was used to put the red, green, and blue phosphor dots on the screen by shining light through the shadow mask from the same angles the electron guns would later illuminate the phosphors. This ensures that the red, green, and blue phosphor dot pattern lines up (fairly) accurately with the shadow mask.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#59
post #17

Tektronix did it with a totally wild set of LCD color filter shutters over the whole face of the CRT, and then sequential color fields. It meant you got the whole spatial resolution of the display, but one third the temporal resolution. Similar to color-wheels in DLP projectors, really. The system was called NuColor, if you want more detail. The Bayer filter method in TFA is sensitive to perfect alignment between the…

An LCD panel backlit by a CRT or a DLP projector was/is a way to make a high-dynamic-range display. http://anyhere.com/gward/papers/Siggraph04.pdf

I've never forgotten this idea. I'd love to make one someday.

Re: Show HN: Rainbow – an attempt to display colour on a B&W monitor

#60
post #3

This was actually a "thing" back in the 1950s. Apparently the results were awful: http://www.earlytelevision.org/color_filter.html

The Vectrex video game console had special overlays that matched the games layout, for example: http://forum.arcadecontrols.com/index.php/topic,154425.msg16...
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