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Raw Space Image Editing for Dummies

Join me in my labors as I try to teach myself how to grab raw images from NASA or some other generous space agency and edit them into hopefully glorious megafiles for printing. I make a lot of space themed art. I’ve seen other artists doing very cool things with these files and I want in. Maybe you do too.

I did a search looking for raw Hubble images and quickly found Hubble’s lovely archive.  I also found a video tutorial that teaches you how to get and process them.

I am not very digitally minded. I am an analog throwback. (I text with one index finger.) I use photo editing software, but it’s gotten so sophisticated that I don’t own Photoshop anymore and just use web based editors. This is handy because the editor we are going to use today has also abandoned Photoshop. You don’t need it. Ignore the guys in the video when they tell you to fire up Photoshop. FITS Liberator 3 has an image editor in it now.

Feeling reckless, I grabbed the biggest, whoppernator version of an image of the Veil nebula. It’s over 300 mb and I realized that there was a good chance that my laptop would choke on it. Throwing caution to the wind, I moved the file to my desktop. FITS Liberator opened it. I saw a small window display with pretty, black and white parallelogram section of the veil nebula and typical grey image editor fields to mess with.

I follow the tutorial’s instructions. I have never taken a black and white original and edited it to make a lifelike full color image. I have heard of people colorizing old black and white films and photographs, but you can tell they are colorized. The images I see coming from the space exploration community don’t look “colorized”. How do astronomers know what the real color is from these black and white raw images? I go back to the tutorial hoping it will explain.

This image editing is much more sophisticated and technical from what I’ve done in the past. Zoltan Levay expounds on the linear and log settings and the how the B and P values work. I watch the histogram change. I watch as my image’s features change as I copy the video’s steps. I know I’m proceeding in ignorance but I’m lured on by a vision of a luminous, tie-dyed nebula as a print on canvas for an underpainting or some other unscientific abomination. But everything is still in black and white. I have no clue what I’m going to get.

Eventually, Zolt Levay tells it like it is,

“At this point it’s a matter of experimentation…and this is kind of where we shift over from being in the science realm to more being in the art realm. So there’s a lot of more subjective choices here. We are not talking about photometrically accurate astronomy here. We are not talking about measuring brightnesses of things. We are not talking about measuring positions of things accurately like an astronomer would do. They would be working on the raw data.”

This is good news because my use of these images will be entirely subjective.

Reckless as I am, I use all of my self-restraint to refrain from clicking the 32-bit per channel option. Mr. Levay assures me 16-bit is plenty and 8-bit with artifacts sounds like an artsy option for another time.

FITS Liberator 3 crashes anyway.

By now I am flustered because the file they were working with in the tutorial had three layers and I grabbed a file with only one layer. I look back at the file server and see that the veil nebula target comes in FOUR different files. None of them are labeled R, B, or G. I have no idea which three to pick.

I watch another FITS Liberator tutorial.

This is no help. I realize I am missing a lot of vital information. I’m stuck. It’s time to try another resource. I do another search for “space image editing tutorial”.

This time I hit pay dirt.


The Planetary Society produced excellent and very thorough Space Image Editing Tutorials by Emily Lakdawalla. I was encouraged because I have followed Emily Lakdawalla on Twitter for years. She is a great science communicator and makes jaw-dropping space images. For her method we don’t need FITS Liberator. She clearly and simply teaches us how to do just about everything in GIMP freeware, or Photoshop. There are about four and a half hours of detailed instruction that will make you a well-informed amateur.

The most important thing that Emily Lakdawalla explains is that most of the space cameras are taking pictures in small slices of light wavelengths. To make beautiful, human eye-pleasing images you have to choose and combine files from different color filters–that usually approximate to red, blue or green–to get something that looks natural. Many of the space exploration agencies are kind and indicate which frequency they captured in the file name. A file capturing a red wavelength might have the number 670 or thereabouts in it. An invisible-to-us ultraviolet shot would be tagged somewhere in the 300s.

She then demonstrates how to fix each file, align them, and combine them to make pretty pictures. She emphasizes that a lot of the science is done in the black and white data. Combining the images is done for us to be able to view and appreciate them in the way we are used to.

We are led on a tour of some of the richest sources of raw space image files as of 2009 when these tutorials were produced. She reminds us that even though all of these files are common domain and available to use, it is important to credit the space agency or mission responsible for bringing us these images. Lakdawalla points out the differences in image taking equipment and idiosyncrasies of file naming and processing challenges for each.

Finally, she points out, if you are pressed for time, lots of the most dramatic images have already been processed for us and uploaded in ginormous image .tiff files to many of these servers. Just sitting there. Waiting for us to do unspeakable art things to them.

That said, you have a lot more creative possibilities when you manipulate the raw images. For example, it might be cool looking to choose not to align features and oversaturate all the layers. Or you might decide to combine only two layers and make a moon in one of the Pantone colors of the year, convert the file to CMYK, and print a throw pillow.

From 9.7 AU to your sofa. Abomination.



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