Hi Bizi,
Quote:
Originally Posted by bizi
mari, do you think they color them?
bizi
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Most APOD images are not manipulated. There can be differences between actual color and image color due to the selective wavelength photography Steve describes.
The visible light spectrum is a continuum of colors from violet to red. Every hue of color corresponds to a different wavelength. Ultraviolet and infrared are not in the visible spectrum and do not correspond naturally to visible colors. UV has wavelengths shorter than visible violet, while IR has wavelengths longer than visible red.
When you take pictures that filter out certain wavelengths, image hue can be lightened, darkened, or shifted. In addition the reproduction of ultraviolet and infrared light as a colored area will alter hues in the resultant photo, or produce color where the naked eye would see none (since IR and UV are not visible to us). Again this is not due to image manipulation or "coloring" but due to the way light is captured.
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Occasionally, there are images on APOD that are not photos, but
artistic compositions based on photos. The descriptions I have seen of these are very explicit and indicate how the composition was created.
waves