The article attempts to explain the difference between "colors" perceived by human eye, vs. wavelengths and signals received by artificial and scientific instruments.
"How much" isn't a question that makes sense, unless you are looking at a specific set of images. Astronomical images can be generated in many, many ways from all sorts of processes. Sometimes there is natural color included, but enhanced; sometimes a wider spectrum is mapped into visible colors so humans can appreciate it; sometimes, the colors are codes for different features, and there is a key provided, so that the colors can be interpreted to what they mean, rather than corresponding to visible light.
It's not just astronomical images, but all disciplines of science use color keys to depict things that are not colors. Look at a topographical map, and it may have green and brown areas that are simply abstracts. A political map uses 5-6 colors to highlight the shapes states or nations, but these are not "real" colors either. But usually, you're provided a color key, for interpretation.
"How much" isn't a question that makes sense, unless you are looking at a specific set of images. Astronomical images can be generated in many, many ways from all sorts of processes. Sometimes there is natural color included, but enhanced; sometimes a wider spectrum is mapped into visible colors so humans can appreciate it; sometimes, the colors are codes for different features, and there is a key provided, so that the colors can be interpreted to what they mean, rather than corresponding to visible light.
It's not just astronomical images, but all disciplines of science use color keys to depict things that are not colors. Look at a topographical map, and it may have green and brown areas that are simply abstracts. A political map uses 5-6 colors to highlight the shapes states or nations, but these are not "real" colors either. But usually, you're provided a color key, for interpretation.