What if.
What if we could only see in the infrared, or only in the ultraviolet? Let’s make it the near IR or near UV, because the width of both the UV and IR bands is far wider than the visual band. Being near IR, we wouldn’t see the red and yellow that thermal imaging cameras see, because thermal infrared has a much longer wavelength than near IR.
For starters, colours would all be different. Chemists have gone to a lot of trouble to generate dyes that produce colours in the visual band, naturally bright colours are rare.
Other things that are obvious is that the transparency of glass is selected to match the visible range. The Sun is brightest in the visible range and less bright at other wavelengths. In IR the sky would be much darker. The Milky Way would be brighter in IR wavelengths and fainter in UV wavelengths. If you go far enough into the UV, the universe itself becomes opaque, due to the Lyman alpha absorption of UV light by neutral hydrogen. On the other hand, if you go far enough into the IR range, at some wavelengths the sky becomes opaque and at other wavelengths relatively clear, but never as clear as in the visual range.
In the IR, black becomes the new coloured. Organic molecules that are black in the visual range become coloured in IR, and the variation of that IR colour with wavelength is used by spectroscopists to identify chemicals, so expect burnt toast to be a very interesting and variable colour in the IR. Other organic chemicals that are black in visible light would pick up colour in near IR as well, so expect black hair to beomce coloured, ditto black clothing, black plastic, black window tinting in cars.
Rainbows extend into the near IR and near UV, though not the far IR or far UV, so should still be recognisable despite having somewhat weird colours and diameters.
Artificial lighting is a topic in itself. Incandescent lights are much brighter in IR, and fainter in UV. For fluorescent lighting it may be the opposite, fluorescent lighting is tuned to produce light in a few narrow spectral bands generating much less IR, but on the other hand the core light source of fluorescent light is UV, and how much of that penetrates to the outside of the light tube will depend on how translucent the coating is to UV. I don’t know much about LED lighting, but suspect, based on the lower energy consumption, that it will be much darker in both IR and UV than in the visual range. That makes watching an LED TV screen much less satisfying experience in both IR and UV. Watching a cathode ray tube TV in either near IR or near UV could be interesting in a weird sort of way.
Questions
What is the transparency of water to IR and UV? Most transparent in UV?
What is the transparency of glass to IR and UV? Snell’s law and reflection?
What are appropriate 3 colour wavelengths to choose for UV and IR sight?
What are the transparency bands of the atmosphere in IR?
What is the Lyman alpha wavelength cutoff in UV?
Any multicolour IR or UV images on the web?
What is the wavelength range for solar flares?
What is the brightness cutoff for sunlight in IR and UV?
Sparkle of diamonds? Of crystal glass?
Colour of timber in IR?
Wavelength bands of chlorophyll?
IR absorption of black paint?
Other absorption in UV? I’d expect there to be more.
White paint in UV? Black paint in IR?
Would boiling water or hot oil glow red in IR?
How does all this affect the colours we would see if restricted to only seeing in IR or to UV?