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.
PJ08, POI: South Polar region
This image is derived directly from the raw image consisting of framelets taken while JunoCam was rotating together with Juno.
The raw values are decompanded according to a documented decompanding table and multiplied by a linear weight that is specific to each color channel, and known only approximately.
Known repetitive camera artifacts have been marked as invalid, and are patched by nearby colors in cases only one color band is invalid. In rare cases where two color bands are marked invalid colors haven't been patched and may show up locally as repetitive spots.
But most single bright pixels are likely to be energetic particle hits.
Trajectory data retrieved from SPICE kernels have been used to adjust for changes of perspective when merging the framelets, and in order to reproject the scene to Juno's position at the image stop time.
The image is approximately illumination-adjusted by a slightly modified polynomial of 5th degree and of the cosines of the solar incidence angle and the emission angle, hence with 21 coefficients, relatively fitting best to the green channel of about one million random samples taken from the Perijove-06 TDI-2 images except the one with a shadow of a moon.
After approximate illumination adjustment, the image has been enhanced by gamma-stretching of the brightness of each RGB value to the 4th power of radiometric values. The resulting intermediate and transient image has been brightness adjusted in a linear way by using the 99.9 percentile as a reference value.
Neither white-balancing nor sharpening has been applied.