How is the aesthetic process in the images taken by the James Webb telescope

Experts affirm that this work stands out for using “false” colors to highlight details that are not visible to the naked eye of any viewer.

The prominent appearance of the Carina Nebula in the first images released by the James Webb Telescope owes much to Alyssa Pagan. As an image science programmer at the Space Telescope Science Institute, she is one of the processors who translates the data collected by the telescope into something not only visible, but also worth seeing and understanding.

Pagan calls the work a collaboration between data, aesthetic principles built over decades of scientific research, and subjective taste. This collaboration is necessary for several reasons, one of which is the enormous distance between Webb and the observed objects.

How experts study the colors in the images captured by the James Webb

To get here, JWST uses the infrared spectrum. Since humans can’t see infrared, scientists like Pagani must make decisions about how to make that information visible. By understanding these options, viewers can get much more information than just an attractive image to the human eye.

For example, Pagan often wonders about colors. JWST records narrowband information, that is, very small wavelength ranges of the infrared spectrum that correlate with the presence of certain elements such as hydrogen, sulfur, and oxygen.

They are colored according to the principle of chromatic order. Shorter wavelengths like oxygen combine colors with shorter wavelengths like blue etc. They overlap and form the background of the image.

Chromatic order of the Carina Nebula

Since hydrogen and sulfur bands correlate with red hues, hydrogen is often given a more yellow filter to show details more clearly in the final product. This results in the ‘Hubble Palette’, so named because an earlier telescope popularized it.

These images are sometimes called “false” colors. But Pagan insists that the colors represent real data. With the correct information, scientists can read them like a map. For example, Webb’s image of the Carina Nebula clearly shows that the lower red part is dominated by hydrogen and sulfur, while the upper blue part is dominated by oxygen:

After using these primary colors, it’s all down to “taste,” says Pagan. He could move the entire palette up or down the spectrum, making blues more purple or vice versa. Contrast is likely to be increased, as in the Carina Nebula, where more colors stand out.

More objective changes have also been made, such as cleaning up possible artifacts like stray light from the telescope, but at this point the two processors may receive different images:

The Carina Nebula upside down

Photographs of space that anyone can enjoy and understand

Pagan’s goal is to make the images “digestible” for the everyday viewer while maintaining their charm. Hubble and Webb aesthetics are not the only focus of professional and amateur scientists or star photographers.

It’s popular with industrial photographers in part because using a narrow-band approach helps avoid light pollution issues, according to Public Science’s Dylan O’Donnell.

Just as they decide what to capture and in what direction, processors can use different color palettes to interpret these narrow filters. For example, another popular approach is the ‘CFHT Palette’, named after the Canada-France-Hawaii telescope.

The differences between the Hubble and CFHT palettes are mainly due to alterations in the color order. Hubble gives hydrogen a more yellow filter based on a different potential wavelength, while CFHT pushes sulfur higher up the color spectrum, resulting in greenish-purple nebulae that exhibit different detail.

The choice of filters is a matter of preference. While O’Donnell says most people want to stay as natural as possible, her own work also highlights the benefits of using “false colors” to show detail, as in her two images of Eagle Black: one using true colors and one using false colors. the other from Hubble.

By comparing them, he reveals the advantages of the latter in showing structure and depth. The yellow-white dust stands out against the blue background of the Hubble palette and looks much more detailed, while the various shades of pink in the true-color version look flat and more difficult to analyze. Below you can see:

The CFHT palate

Today’s telescopes already take color pictures

Lastly, JWST itself is also known to be producing color images that may be unexpected to some. Recently, several images of Jupiter were released, with the curiosity that the planet appears to be blue.

Although Hubble took images of Jupiter that appeared simultaneously blue and red, in the most recent image, even the famous Red Spot appears white due to reflected sunlight.

Pagan (who did not process this particular image) says that the palette was probably intended to highlight the aurora, which appears red in contrast.