Such as photos of nebulas or galaxies. I remember something about using filters of different gases but that’s it.
In: Technology
Usually photos are a combination of different filters and wavelengths. Rarely there is a very colourful photo of space with only a normal filter (naked eye so to speak).
Filters are used to enhance detail and contrast, which can give you info which might be lost while otherwise.
Different wavelengths are used to find info which cannot be found in visible light spectrum. Infrared can be used to research objects behind stellar dust while synchrotron radiation is known for certain processes and associated to certain objects
Most photos of nebulas or galaxies are made using light our eyes can’t see (like infrared or UV).
Their “colors” are remapped to colors we can see, so we can actually look at them. This is an artistic process as there is no “correct” way to map colors we can’t perceive to color we can, which is why space photos are usually that colorful.^[1]
Some pictures taken using visible light also have their colors remapped, just so that they look better. (There is nothing special about visible light -beside the fact that we can see it- so the process makes sense for it too).
[1] In some cases you can still find raw version of these images, without the recoloring, but these are just arrays of values, so you’ll have to remap them yourself, or just use them as is.
In a few different ways, depending on the purpose.
1. they are digital colored to make them striking and beautiful. to varying degrees this _may_ be done consistent to number 2, below.
2. different data is color coded. For example, many “telescopes” aren’t looking at visual spectrum at all, so to make it useful to our eyes data is color coded. this is a sort of “translation”.
No they are all artist digitally retouched. There might be vibrant colors of the different gases in space but we cannot see them with the tools that we currently have. But we know that different gases when ignited burn different colors so we can theorize what some nebulas might look like because we can spectral analysis their elements to know what they’re made of and how hot they are. But all the colorful photos of space are digitally edited for color vibrance. [I like this article about it.](https://www.space.com/8059-truth-photos-hubble-space-telescope-sees.html)
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