IMAGE PROCESSING GALLERY
For those of you who have contributed – thank you! Your labors of love have illustrated articles about Juno, Jupiter and JunoCam. Your products show up in all sorts of places. I have used them to report to the scientific community. We are writing papers for scientific journals and using your contributions – always with appropriate attribution of course. Some creations are works of art and we are working out ways to showcase them as art.
If you have a favorite “artist” you can create your own gallery. Click on “Submitted by” on the left, select your favorite artist(s), and then click on “Filter”. For other tips about the gallery click on the “Gallery Organization” tab.
We have a methane filter, included for the polar science investigation, that is almost at the limits of our detector’s wavelength range. To get enough photons for an image we need to use a very long exposure. In some images this results in scattered light in the image. For science purposes we will simply crop out the portions of the image that include this artifact. Work is in progress to determine exactly what conditions cause stray light problems so that this can be minimized for future imaging.
The JunoCam images are identified by a small spacecraft icon. You will see both raw and processed versions of the images as they become available. The JunoCam movie posts have too many images to post individually, so we are making them available for download in batches as zip files.
You can filter the gallery by many different characteristics, including by Perijove Pass, Points of Interest and Mission Phase.
A special note about the Earth Flyby mission phase images: these were acquired in 2013 when Juno flew past Earth. Examples of processed images are shown; most contributions are from amateurs.
The spacecraft spin rate would cause more than a pixel's worth of image blurring for exposures longer than about 3.2 milliseconds. For the illumination conditions at Jupiter such short exposures would result in unacceptably low SNR, so the camera provides Time-Delayed-Integration (TDI). TDI vertically shifts the image one row each 3.2 milliseconds over the course of the exposure, cancelling the scene motion induced by rotation. Up to about 100 TDI steps can be used for the orbital timing case while still maintaining the needed frame rate for frame-to-frame overlap. For Earth Flyby the light levels are high enough that TDI is not needed except for the methane band and for nightside imaging.
Junocam pixels are 12 bits deep from the camera but are converted to 8 bits inside the instrument using a lossless "companding" table, a process similar to gamma correction, to reduce their size. All Junocam products on the missionjuno website are in this 8-bit form as received on Earth. Scientific users interested in radiometric analysis should use the "RDR" data products archived with the Planetary Data System, which have been converted back to a linear 12-bit scale.
MG, It's Full of Stripes! (PJ11_27)
Two intermediate images from the Juno28g raw processing pipeline prior to being merged into final image. These images are composed of odd and even JunoCam frames, and give a hint at the underlying complexity of turning JunoCam raw data into pretty pictures.
For fun, open in Photoshop, Select All, Layer New Layer via Copy, Layer Blending Lighten, move new layer up until bottom image overlaps top.
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“Juno28g”, a JunoCam raw processing pipeline implemented in Mathematica, is available under permissive open source license at https://github.com/BrianSwift/JunoCam
This basic pipeline implements pixel value decompanding, lens geometry correction, equirectangular projection, and assembly of raw frames to a final image. Only a per-channel scaling is applied for color balance, leaving beautification in Photoshop to the user’s artistic interpretation.
Works with MissionJuno website formatted -raw.png and PDS .IMG or .IMG.gz raw image files.
Usable images are produced with the defaults parameters. But the appearance of seams can be reduced by refinement of parameters related to Juno spin rate and JunoCam orientation relative to the spin axis.