False Color?

[mustang292]

Can someone tell me what "False Color" means when NASA describes some of the pictures they take of space. It looks like Real Color to me!

[insane_alien]

it means that the picture is either taken outside the range of human vision(UV or IR) or that it has been edited for greater visibility of certain aspects (mineral locations, gaseous composition, umm ok i don't really know what else but i'm sure nasa does.)

[mustang292]

Okay, maybe I'll simplify what is confusing me. In an unrelated post someone has a black and white picture of a dead dog. Then they have another picture of it in Color, But they refer to it as a "False Color" picture. Is it that this person shouldn't have used that as a description or what?

[insane_alien]

umm i don't see it reffered to as a false colour image assuming you mean this thread.

 

although the picture does look like its 256-colour which just means it uses 256 different colours.

[mustang292]

Wow, that is the thread I was talking about, but now, I can't even find where it was stated! I might be going nuts! Thank you for you original definition though. It does give me enough to understand.

[insane_alien]

were you reading a nasa article before it?

[AzurePhoenix]

is he talking about where the original image is recorded as greyscale and later the "proper" color is applied? I thought the rovers worked that way.

[swansont]

it means that the picture is either taken outside the range of human vision(UV or IR) or that it has been edited for greater visibility of certain aspects (mineral locations, gaseous composition, umm ok i don't really know what else but i'm sure nasa does.)

 

It can also be that the color correlates with some value, like intensity, e.g. blue is an intense source while red is weak.

[mustang292]

is he talking about where the original image is recorded as greyscale and later the "proper" color is applied? I thought the rovers worked that way.

 

Yes, Pretty much, that is what I mean. I would consider greyscale to false color, but they refer to the "proper" color as the "False Color".

 

I guess its like, Why do we park in a driveway and drive on a parkway?

[insane_alien]

well it would be false colour if the colour was added in later. like the old photographs and film where colour was added.

[padren]

Yes' date=' Pretty much, that is what I mean. I would consider greyscale to false color, but they refer to the "proper" color as the "False Color".

 

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If the original is grayscale, the film could only detect the shade instead of the color, based on how light naturally hit the film through the lense.

 

This is "true" to nature and the true color. When you modify the grayscale image you need a human to "decide" what colors to place where within that photo, which isn't based at all on the colors naturally detected and burned into the film (since there were none). That is why its false color.

 

Likewise, nasa can photograph a nebula, but in "natural true color" it will be just a big black field with maybe a few stars shining through. However, since their film (okay not film but the digital equivelent) is designed to pick up a wide spectrum of wavelengths of radiation, they can "decide" to assign different visual colors that we can see to those radiation wavelengths, which reveal the form of the nebula mass. This is also false color, because naturally all we'd see is a big black patch of space with a few stars shining in it and some human has to decide how to adjust it to make it visible and pretty.

[Rocket Man]

they use false colour in electron microscopy, you cant get much colour from the original image but the texture detail is the important part, the false colouring is used to clearly show different materials/sections of a specimin.

normally it's just an overlay of colour on the image determined by a series of algorythms, for example i've seen pictures of hot pink and green beetles (black beetles as seen without false colour) but the false colour is often used to mimic what would normally be seen.