Comment by creatonez | Hacker News Reader

Comment by creatonez | Hacker News Reader

Parent Full thread

Keep in mind that Pillars of Creation is not supposed to be intentionally beautiful. It's a false color image for maximizing research value. Green for hydrogen band, red for sulfur band, blue for oxygen band. The goal of the processing is to minimize the error in these three readings, to study the ionized gas in the cloud as it truly is. If it were engineered for the public to look in awe, you could probably come up with an even more striking coloring than a simple RGB assignment. This is something a lot of people get wrong about the topic of false color images -- usually, there is not a separate "for the public" and "for researchers" image. The media outlets just pulled the coolest looking processed images out of actual research papers, and some of them were so cool looking they became cultural icons. (The exceptions to this, ironically, are when an image is intentionally processed to be as close to true color as possible -- which makes it less useful for research purposes, but fantastic for writing explainers for laymen on the topic of false color images.)

Though, you could say it's indirectly designed for beauty. When astronomers process an image, they are looking for interesting features to study. And once you've narrowed in on the most scientifically interesting way to process an image, the sorts of striking color contrasts that creates are inherently beautiful because they are unveiling the interesting parts & letting us see the unseen for the first time. And there is selection bias on what is interesting to look at. A violent explosion is both more aesthetically inspiring and teaches us more about how matter works than a picture of a random stairwell, and astronomers love their violent explosions.

Astronomers rarely look at color images. These color images are produced by press offices for the public.

That being said, the complaint that the images are "unrealistic" are off-base. The images accurately portray the information that was captured by the telescope. Your eyes often can't even see the wavelengths imaged by space telescopes (like the James Webb Space Telescope), so how you map those wavelengths to RGB is largely arbitrary. As long as you map them in the same order (shorter wavelengths appear bluer, longer wavelengths appear redder), I would consider the images accurate.

This is just not true, though. Astronomers look at color images all the time, in certain areas of research at least. Many color images in the media are copied directly from research papers, since image processing can be rather labor intense to be done just for PR purposes (mainly because you have to essentially calibrate the positioning and noise characteristics of the sensors from scratch -- the color assignment part can actually be done in vanilla photoshop). This is something I feel the article skipped out on explaining, that these false color images are actually research tools the same way that the grayscale images are.

It is true that they also look at a lot of grayscale images, though. Differentiating chemicals in nebulas or on the surface of planets isn't always necessary, and you can always take the simpler (but sometimes less useful, since it doesn't make full use of the human visual system) route of looking at multiple grayscale images. A lot of the areas where false color is most useful are well-trodded ground, so we don't necessarily need more images of the same objects when the existing body of research is already rich. And sometimes, a researcher includes an image in their paper just because they thought it looked cool, not because it was useful for the methodology.

Astronomers almost exclusively look at grayscale images (sometimes with an applied colormap, but the underlying data is still just a single channel) when doing actual work.

There are some rare cases in which an audible might look at a color image, but the overwhelming majority of images astronomers deal with daily are grayscale.

That's not right. I'm an astronomer, and I often look at colour images and colleagues do, too. For example, the galaxies in a cluster of galaxies follow a relation of colours - brightness (the "red sequence"), which can be used to detect the cluster. The eye is also quite good at helping confirm a cluster by spotting the galaxies following this sequence. I also use colour images to help identify spectral changes that change across an image, in my case in the X-ray waveband.

Most astronomers look at the red sequence on a scatterplot, with each point being based on the measured fluxes of one galaxy. Very few astronomers are literally looking at color images to eyeball these measurements.

There are edge cases in which astronomers will load up images at multiple wavelengths and overlay them, but this is not the normal case. By and large, they're looking at a single channel at a time. Even more commonly than that, they're working with catalogs automatically generated from images.

You are plainly wrong. I know several astronomers who look at colour images to check that the software is working properly.

"Several" out of how many? This just isn't common in astronomy, outside of public outreach.

Color Images imply that they are real colors. If they are not, that's misleading.

There are real colors. Your eyes are just incapable of seeing them.

Would you rather thaw NASA show you a blank image and say, "This is our newest infrared image from the James Webb Space Telescope!"

They map the images into wavelengths you can see. There's nothing else the can do, other than not showing you the images at all.

Nonsense.

A screenshot of this page would capture a title bar in orange.

The REAL title bar is displayed as dots of green, blue, and red; no orange is present.

Reply on news.ycombinator.com