Television without primary colors

Question

As humans, we're incredibly lucky that we only see in three primary colors. It makes the development of color displays quite easy. We only need to squeeze three subpixels into a single pixel!

What if, instead, our eyes had evolved to be more like an optical spectrometer than a CCD camera, so each photoreceptor could tell what wavelengths were hitting it? A green leaf would not be green, but would contain hundreds of distinct colors even at the same point, with green merely being the most prominent. A modern RGB display would look to us like three monochrome displays of different colors superimposed on top of each other and varying in brightness only, not wavelength.

How might development of the color television changed in this situation? Would we still be watching in monochrome, or are there any promising techniques that might have allowed a color display to exist that would satisfy our superior vision without being prohibitively large or complicated?

Answer 1

1. you should look at squid eyes and shrimp eyes for other ways to achieve color vison.

2. combining colors still works fine because every cell in they eye either has to take take the sum of colors hitting it or the eye ends up with ridiculously low resolution. either the cells detect a tiny margin of the spectrum and thus have very low resolution, or they detect a larger part of the spectrum and get an aggregate signal or it splits the light at the point of each cell which again makes for very low resolution. The more subdivided and discreet the spectrum being sampled the more cells you need just to sample them all or the cells have to be much larger to divide the light entering it, either way you have the same problem they are competing for space and drastically reduce the resolution.

Also because of the speed vision needs to work at and how nerve impulses work a cell either needs to be sending a binary or intensity signal, anything else requires chemical signaling which is too slow. A spectrometer's signals is limited by how many discrete colors your sampling can get for a given beam of light, an image is limited by how many discrete sample points you have per surface area, the two are competing which each other for surface area in the eye. You can't sample a single unit area of light for everything unless you make that area very large.

Light from the environment is not clean if it has passed through and been reflected by many media before reaching an eye, and these variable are constantly changing. so having something like a spectrograph also makes little sense since it won't tell you anything useful.

To put it simply you can either see the shape leaf, or see all the individual spectra being reflected by the leaf and everything around it, not both.

You would really need to figure out how such an eye could work before any kind of answer can be given, because using normal biology it can't exist and form a decent image at the same time.

Answer 2

This just being pure conjecture, and not entirely related three primary color displays would and could still be feasible in us e, but could be better described, to use a direct t analogy as equivalent to black and white displays. Black and White tv was still a medium for entertainment,so a three-color, or five-color display COULD still end up being used in the same way, and I would imagine, not being an expert with regards to anything yet that it would end up sticking around for longer due to the difficulty of creating a display which would simultaneous emit several different bands of light. And a secondary question, are you an alien?(Sorry, now that I look at the question I see that it doesn't really make much sense. I should have given the question a bit more consideration)

Answer 3

Not only television, but "colo(u)r" photography and moving pictures development in such a world is difficult. I imagine black and white would dominate for quite a long time, at least the chemically produced pictures.

As for TV - it would probably start with low-resolution (Baird-like) electromechanical attempts, then move to fully electronic system, still monochrome - no difference from our technology until 1950 or so. Then it depends on the exact mechanism of eye sensitivity to the spectrum. Evolution would not favour total discrimination of the wavelengths, because then leaf (or predator) would look very differently on a sunny day and when it is overcast - and you definitely do not want this (see also quite fantastic automatic white balance of human vision). Much like we have psychoacoustic models (much used in sound compression), there would be a spectral response model. And that means you can approximate the spectral response with a function with some parameters. Analogue transmission means you have to sample three dimensional picture (where the 3rd axis is the spectral one), which increases the bandwidth enormously to have any fidelity. So the true "color" broadcasting would have to wait until say the 2000s, with digital transmission, advanced compression methods and a lot of CPU power (and a fine LCD grid to reproduce enough points of the spectral response).

Answer 4

For chemical photography, at least, there is at least one process (perhaps two) that produces color in a manner your "full spectrum" vision would perceive as full color: Lippman plates.

These are made by using an emulsion in direct contact with a reflecting layer (historically, liquid mercury), which is then developed in a conventional manner and produces a direct positive, full color reflective image due to the interference effects of different light wavelengths within the thickness of the photo emulsion.

This was (in our timeline) an accidental discovery based on similar (but not color-accurate) effects that occur on overexposed Daguerreotype plates, and was possible as soon as dry plate emulsions were available (ca. 1870), though the actual process was discovered after tri-color had been demonstrated.

Once the Lippman process is known, it's "just" a matter of inventing a display that can use interference in the same way to display color. We haven't tried, because we don't need it (with our four-color -- two sensor types with two colors each) eyes. Your spectrographic-sighted race may decide they do need this.

Answer 5

You could achieve your goal of television (or indeed cinema) that is not based on combining primary colors using a modified form of DLP (Digital Light Processing), a technology that is currently found in movie theaters and some consumer products.

A conventional DLP projector uses an array of thousands of microscopic mirrors that pivot under digital control such that they either reflect light along the optical axis or dump light into a black heat sink. As digital devices, each mirror (pixel) is either "on" or "off". Conventional DLP uses light sources in the three primary colors or one white light source and a rotating color wheel. That won't work for your species, so . . .

For your spectrally advanced species, instead of each mirror element being a plain mirror, each could be a mirrored diffraction grating that would refract and reflect a specific pure color from a white light source depending on the angle of reflection. (Such diffraction gratings already exist, but perhaps not so small.) Likewise, instead of the microscopic mirrors being designed to have just two states, on or off, each mirror in this device would have to assume any angle within a certain range and could therefore produce any color of the rainbow from the white light source. To prevent color smearing, there would have to be a "shadow mask" similar to that used in color CRTs.

Answer 6

This seems to be a 'Can we see the trees for the forest?' type question.

There are three distinctly different things happening in human vision. One is to differentiate the colors, and the second is to resolve the details of the shape and form. Then, there is the original vision systems, such as that still used by the fly, that senses neither color nor detail, but just motion. Basically, all it resolves is a moving shadow across the vision sensors. If there is no movement, there is no 'vision'.

In humans, our monochrome vision can resolve high detail, as in seeing the trees. Our color vision resolves the overall background color, as in the forest. It seems our eyes map the the overall color detail on top of the detailed monochrome image to create, in our mind, the final 'color' high-res picture. That is, we do not stop using our monochrome sensors just because the light is bright enough to resolve colors. Our color vision adds to the monochrome vision.

I could imagine the eye of this hypothetical being would have to be very similar. That is, monochrome non-differentiated spectrum sensors to determine detail and movement, and the more general spectral image processors to define the color. In terms of pure survivability, the faster monochrome detail and motion response would be a first-alert system, and the slower (I suspect) spectral image processor would provide more information after a very brief lag.

In our first televisions and other image capture media, we generally either used black-and-white images, or color images, and did not combine the two. That is, the original CRT screens were either monochrome or color phosphor screens, but not both. After all, the same color signal activates both the monochrome and color sensors in our eyes. I suspect the televisions of this society might have developed a different dual-process form of television - one that produced very fine monochrome detail imaging, and a second system that mapped color onto this monochrome image. Maybe filters that went over the screen, cycling through the color spectrum, in synch with the monochrome image. That way, the monochrome projects the detailed trees, the color filter device fills in the forest color.