Pictures of Pluto – Free Raw images from New Horizons

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A few weeks ago I mentioned that NASA had posted many images of Pluto taken by the New Horizons space craft (link to all the images).

A caveat

Now technically, these images are not Raw files in the same sense of the term as Raw files from your camera. The photos are available in JPEG form, rather than the original sensor data. That’s OK though, for several reasons.

First, the New Horizons camera is black and white. There is 1000 times less light out at Pluto than on Earth (think of the ISO and aperture settings you would need on your camera!), so by avoiding the need for an array of different coloured sensors, the camera on New Horizons is sensitive enough to take pictures in this low light.

Second, its a little unclear to me whether any of my favourite FOSS photo editors could actually support the original sensor data from New Horizons. NASA receives it from the spacecraft as 12-bit pixel intensities, which it converts to 8-bit JPEGs for the website. Going from 4096 to 256 shades of grey causes loss of tonal range, and limits the full extent of what we can recover in post-processing. However, we can still get a lot out of these images.

All images in this post are courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute and can be found here:

Image 1: Pluto

pluto new horizons
Original picture of Pluto (get it here).

I imported this pic into darktable, and made it a bit more dynamic with levels, curves, and local contrast (i.e. “clarity“). Then I added some colour back in via the colour balance module, and voila, here is a more artistic rendition:

Pluto from New Horizons
Edited picture of Pluto from New Horizons.

Image 2: Space (“the final frontier”)

NASA also posted this image:

"Empty" Space from New Horizons
“Empty” Space from New Horizons (get it here)

At first glance it seems like there’s nothing there, here’s what NASA had to say about the image:

Sometimes the images appear to be blank. This is usually caused by: (a) there are only a small number of objects in the picture that are visible at the selected exposure time (e.g., only Pluto, Charon, and a couple of fairly bright stars are visible in 1×1 mode LORRI images when the exposure time is less than 150 ms), and/or (b) the intensity stretch is not optimized for the limited dynamic range of the signal in the image. In either case, you might want to download the JPEG yourself (the full version, not the thumbnail) and play with the intensity stretch using image processing software on your computer (on an Apple computer, you can use either the Preview or iPhoto applications; there are similar options on other computers). For example, you might start seeing objects if you move the white level of the stretch to smaller values. And you may need to magnify particular regions to see the object(s) better. See what you can find by digging a bit deeper!

That sounds like a challenge to me. Let’s use darktable rather than this Preview/iPhoto nonsense:

Space as seen by New Horizons
Not so empty – using the Levels tool to make stars appear. Best viewed full size to see all the details.

That was achieved with the Levels tool, and a little denoising.

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