Starship Asterisk*

JohnD wrote: ↑Sun Aug 21, 2022 9:58 am Again, have I discovered, and am suffering from, an acquirable form of colour blindness?

Quote blurb, " The featured picture combines visible light from the Hubble Space Telescope in purple, X-ray light from the Chandra X-ray Observatory in blue, and infrared light from the Spitzer Space Telescope in red"
I see purple, blue and white. No red. I know, white light is all wavelengths at once, but when the white dominates the picture, that sentence is unhelpful!

JohnD wrote: ↑Sun Aug 21, 2022 9:58 am Again, have I discovered, and am suffering from, an acquirable form of colour blindness?

Quote blurb, " The featured picture combines visible light from the Hubble Space Telescope in purple, X-ray light from the Chandra X-ray Observatory in blue, and infrared light from the Spitzer Space Telescope in red"
I see purple, blue and white. No red. I know, white light is all wavelengths at once, but when the white dominates the picture, that sentence is unhelpful!

JohnD wrote: ↑Sun Aug 21, 2022 9:58 am Again, have I discovered, and am suffering from, an acquirable form of colour blindness?

Quote blurb, " The featured picture combines visible light from the Hubble Space Telescope in purple, X-ray light from the Chandra X-ray Observatory in blue, and infrared light from the Spitzer Space Telescope in red"
I see purple, blue and white. No red. I know, white light is all wavelengths at once, but when the white dominates the picture, that sentence is unhelpful!

Chris Peterson wrote: ↑Sun Aug 21, 2022 2:37 pm

JohnD wrote: ↑Sun Aug 21, 2022 9:58 am Again, have I discovered, and am suffering from, an acquirable form of colour blindness?

Quote blurb, " The featured picture combines visible light from the Hubble Space Telescope in purple, X-ray light from the Chandra X-ray Observatory in blue, and infrared light from the Spitzer Space Telescope in red"
I see purple, blue and white. No red. I know, white light is all wavelengths at once, but when the white dominates the picture, that sentence is unhelpful!

This is why science doesn't use color images. They may be useful in seeing structure, but are very limited in showing anything else. Our eyes are not spectroscopes. "Purple" is red and blue. We have no way of telling if a pixel is purple because it represents visible light, or if it's purple because it represents a a mix of x-ray and IR. When you create a color image, you lose information.

All color pictures like this should be substantially treated as aesthetic, not scientific.

(Given that there are only three input channels, I would have mapped them to the display primaries of red, green, and blue. This would have resulted in less information loss.)

Ann wrote: ↑Sun Aug 21, 2022 5:08 pm

Chris Peterson wrote: ↑Sun Aug 21, 2022 2:37 pm

JohnD wrote: ↑Sun Aug 21, 2022 9:58 am Again, have I discovered, and am suffering from, an acquirable form of colour blindness?

Quote blurb, " The featured picture combines visible light from the Hubble Space Telescope in purple, X-ray light from the Chandra X-ray Observatory in blue, and infrared light from the Spitzer Space Telescope in red"
I see purple, blue and white. No red. I know, white light is all wavelengths at once, but when the white dominates the picture, that sentence is unhelpful!

This is why science doesn't use color images. They may be useful in seeing structure, but are very limited in showing anything else. Our eyes are not spectroscopes. "Purple" is red and blue. We have no way of telling if a pixel is purple because it represents visible light, or if it's purple because it represents a a mix of x-ray and IR. When you create a color image, you lose information.

All color pictures like this should be substantially treated as aesthetic, not scientific.

(Given that there are only three input channels, I would have mapped them to the display primaries of red, green, and blue. This would have resulted in less information loss.)

Since X-rays and infrared light don't represent visible colors in the first place, I would have had no problems with a black and white image here. That is particularly true since I don't regard the Crab Nebula as intrinsically blue in any way, so I wouldn't feel that a b/w image of the Crab would have robbed us of any "natural" blue light. (A strangely mapped and non-blue color image of, say, the Pleiades or the Trapezium in the Orion Nebula, now that's another matter!) :evil:

However, I actually think that a mapped color image of the Crab might have been more informative than a b/w one, assuming X-rays had been mapped as blue, visible light as green and infrared light as red. For clarity, we could have been shown the individual images (X-ray, optical, infrared) too. And these single filter images might well have been shown in black and white, as far as I'm concerned.

De58te wrote: ↑Sun Aug 21, 2022 5:17 pm I can see 3 colors besides the white. The blue is obvious. What they call purple I would think is the color that looks more precisely like lavender. And the red looks more like a burgundy color. Am I wrong?

Chris Peterson wrote: ↑Sun Aug 21, 2022 5:19 pm

De58te wrote: ↑Sun Aug 21, 2022 5:17 pm I can see 3 colors besides the white. The blue is obvious. What they call purple I would think is the color that looks more precisely like lavender. And the red looks more like a burgundy color. Am I wrong?

I can see hundreds of colors. Interpreting them is the problem.

Just because IR is mapped to red doesn't mean you'll see any red in the image!

De58te wrote: ↑Sun Aug 21, 2022 5:17 pm I can see 3 colors besides the white. The blue is obvious. What they call purple I would think is the color that looks more precisely like lavender. And the red looks more like a burgundy color. Am I wrong?