NGC2359: Thor's Helmet Revealed
Posted: Sat Jan 29, 2022 3:07 pm
I’m not sure that anyone in astro-land will appreciate this, but I just posted a different approach to narrowband processing. Here it is: https://www.astrobin.com/vgosdd/
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NGC 2359: Thor’s Helmet Revealed
This unusual and highly detailed interpretation of Thor’s Helmet was inspired by the writing of Astronomer Travis Rector, author of Coloring the Universe and related scholarly articles. Professor Rector argues that processors of emission nebulas should try to accurately differentiate among a nebula’s ionized gases, while at the same time being mindful of color design theory.
In the past, I’ve been imitating other astro imagers who have been generally pursuing “pretty pictures” with the Hubble palette, or the realistic palette. But Rector’s writing convinced me that I should do some fresh thinking. I should think more carefully about the unique chemical composition of each narrowband object and choose a palette that highlights that object’s individual characteristics. In addition I should apply the basic principles of color design.
To my surprise, I discovered that the Hubble palette is often not the best choice. Most Hubble images are more or less a combination of orange and blue. This is known as a direct complementary color harmony and orange/blue is one of the most commonly used combinations in color design. For example, this is what the “golden hour” and “blue hour” in photography are all about.
In the context of astro processing there might be two drawbacks in using the orange/blue pairing. First, it is seen so often is our hobby that it might have become a stereotype. Second, it omits the hues centered around green, which means that it cannot convey a full range of information about the chemical composition of an emission nebula. It would be better to use triadic complementary colors, rather than a simple pair.
This is an on-going experiment, but at the moment I’m using these steps for three channel narrowband projects:
Step 1. Open the three narrowband masters in PixInsight and carefully study and compare the signals in all three channels.
Step 2. Generate images of all six of the narrowband palette options by using a process container in PixInsight that automatically creates six channel combinations, and then tile the images across the PixInsight window.
Step 3. Choose the channel combination that best shows the chemical composition of the object, while attempting to observe basic principles of color design.
Step 4. Process the image, using that palette, in StarTools. Do not modify the hue of any part of the object of interest.
Step 5. Use Affinity Photo to add the color key, copyright notice, final tweaks, and creation of various file formats. Do not modify the hue of any part of the object of interest.
In the case of NGC 2359, I choose the HOS palette. The resulting hues are close to a triadic complementary color harmony of yellow-green, blue-violet, and red-orange (using the terminology of my color wheel). The color key translates hues into Ha, OIII, SII and mixtures thereof.
Tech Notes for ASA 500/3.6:
ASA Newtonian, 500 mm aperture, 1900mm focal length, F3.6
FLI Proline 16803, 9 μm pixel, 4096 X 4096
ASA DDM85 equatorial mount
Processing with PixInsight, StarTools, and Affinity Photo
************************
NGC 2359: Thor’s Helmet Revealed
This unusual and highly detailed interpretation of Thor’s Helmet was inspired by the writing of Astronomer Travis Rector, author of Coloring the Universe and related scholarly articles. Professor Rector argues that processors of emission nebulas should try to accurately differentiate among a nebula’s ionized gases, while at the same time being mindful of color design theory.
In the past, I’ve been imitating other astro imagers who have been generally pursuing “pretty pictures” with the Hubble palette, or the realistic palette. But Rector’s writing convinced me that I should do some fresh thinking. I should think more carefully about the unique chemical composition of each narrowband object and choose a palette that highlights that object’s individual characteristics. In addition I should apply the basic principles of color design.
To my surprise, I discovered that the Hubble palette is often not the best choice. Most Hubble images are more or less a combination of orange and blue. This is known as a direct complementary color harmony and orange/blue is one of the most commonly used combinations in color design. For example, this is what the “golden hour” and “blue hour” in photography are all about.
In the context of astro processing there might be two drawbacks in using the orange/blue pairing. First, it is seen so often is our hobby that it might have become a stereotype. Second, it omits the hues centered around green, which means that it cannot convey a full range of information about the chemical composition of an emission nebula. It would be better to use triadic complementary colors, rather than a simple pair.
This is an on-going experiment, but at the moment I’m using these steps for three channel narrowband projects:
Step 1. Open the three narrowband masters in PixInsight and carefully study and compare the signals in all three channels.
Step 2. Generate images of all six of the narrowband palette options by using a process container in PixInsight that automatically creates six channel combinations, and then tile the images across the PixInsight window.
Step 3. Choose the channel combination that best shows the chemical composition of the object, while attempting to observe basic principles of color design.
Step 4. Process the image, using that palette, in StarTools. Do not modify the hue of any part of the object of interest.
Step 5. Use Affinity Photo to add the color key, copyright notice, final tweaks, and creation of various file formats. Do not modify the hue of any part of the object of interest.
In the case of NGC 2359, I choose the HOS palette. The resulting hues are close to a triadic complementary color harmony of yellow-green, blue-violet, and red-orange (using the terminology of my color wheel). The color key translates hues into Ha, OIII, SII and mixtures thereof.
Tech Notes for ASA 500/3.6:
ASA Newtonian, 500 mm aperture, 1900mm focal length, F3.6
FLI Proline 16803, 9 μm pixel, 4096 X 4096
ASA DDM85 equatorial mount
Processing with PixInsight, StarTools, and Affinity Photo