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Juno PDS data
wildespace
post Jun 28 2016, 07:11 AM
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QUOTE (mcaplinger @ Jun 27 2016, 06:49 PM) *
We didn't take any RGB images of stars and the zodiacal light.

I see. Emily's page gave me an impression that you did, with headers like:
QUOTE
2013107_00C048
Filters: BGR


I used IMG2PNG to create JNCE_2013107_00C048_V01.png but as I don't know much about processing such images, I got a black stip with barely a hint of what looks like noise. And I also don't know how to combine that raw imagery into an RGB composite.


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Gerald
post Jun 28 2016, 12:14 PM
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This is a 16-fold brightness-stretched and 2-fold enlarged crop of 2013107_00C048:
Attached Image

It shows one copy of a pattern which repeats each 3x128=384 pixel rows in the raw swath.
Those repetitive patterns are mostly caused by hot pixels. But there exist some repetitive spots of different type, too.
The 3x128 pixels are resulting from exposures made of three color bands times 128 pixels framelet height.

This is a 16-fold enlarged crop:
Attached Image

It shows a vertical line of 4 bright pixels. This line is the result of one hot pixel on the CCD copied 4-times by the TDI mechanism. It indicates, that 4 TDI steps have been applied for this image. - TDI 4 is hard for finding many stars. TDI 64 and TDI 80 are much better-suited for this purpose.
The 16x16 noisy block indicates, that the image has been compressed lossily on macroblocks (tiles) of 16x16 pixels.


When looking for real objects, first mark all repetitive patterns, or clean the image from these patterns.
Then decompose the swath into framelets of height 128 pixels, grouped into exposures of 3 framelets. Insert a gap of 27 pixels between neighbouring framelets within one exposure. Assign a color channel to each framelet within each exposure. Shift the exposures vertically, until you get a match of corresponding features (about 114 pixels, give or take a few). Use the valid color channel of each exposure to obtain full rgb coverage. The result will be a first draft of an RGB image. I'd recommend to use 2013282_000C91 (aka EFB01), showing Earth's moon, as a first exercise.
The first 22 slides of the pdf I've provided a few weeks ago should apply to moon and star RGB images, as well. Spacecraft trajectory and rotation of the target objects can be neglected for distant targets.
You may use weights for the colors in order to adjust the raw colors, if you use EDRs; the weights for the colors are likely to undergo refined calibration.
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mcaplinger
post Jun 28 2016, 02:16 PM
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QUOTE (Gerald @ Jun 28 2016, 04:14 AM) *
This is a 16-fold brightness-stretched and 2-fold enlarged crop of 2013107_00C048:

This particular image was part of a mapping operations test. Since it has a short exposure, it likely doesn't show any real objects, just noise.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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javierluiso
post Jul 2 2016, 03:33 AM
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QUOTE (wildespace @ Jun 27 2016, 04:59 AM) *
I don't know how to work with IMG files (they won't even mount on a virtual drive on my laptop), so could someone please post JunoCam's RGB images of stars and the zodaical light? Information about the exposure for those images would be appreciated too.

Thanks smile.gif


Hi, I've been working to load and process .IMG file using Octave / MATLAB scripts.
Take a look to https://javierluiso.wordpress.com/, I hope my work will be useful to you.

Javier
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JohnVV
post Jul 2 2016, 07:13 PM
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any reason you are not opining img files as a raw whit a header
or
using img2png
or
using isis3
or
using vicar
or
using ???

now Juno data is a bit odd and needs a lot of processing
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Gerald
post Jul 2 2016, 08:47 PM
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Reading the IMGs is just the first small hurdle. The IMGs are raw binary data streams without an embedded header. More important is opening the files in a tool or with a computer language you're used to, and which is sufficiently powerful to perform the sophisticated processing.
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mcaplinger
post Jul 2 2016, 09:05 PM
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QUOTE (Gerald @ Jul 2 2016, 12:47 PM) *
The IMGs are raw binary data streams without an embedded header.

"raw binary data streams"? They're just normal 2D images, in row-major order, with 8 or 16-bit pixels. You could load them raw into Photoshop if you read the image dimensions out of the label manually.

Unpacking the framelets might be a bit of a challenge, but we do that for you with the image releases that have actual content, like EFB.

Most simple manipulations are a few lines of code in any modern processing environment.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Gerald
post Jul 3 2016, 06:25 AM
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To me, the most easy file format to handle is the EDR IMG format, as provided in the MSSS PDS. But I can't assess, whether I'm representative.
Essential for fast and good results is early accessibility to these files. But I can handle the RDRs, too.
If intermediately processed images will be the only available, I might need to reconstruct the EDRs as far as possible.
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Gerald
post Mar 8 2017, 04:05 AM
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Juno PDS Imaging Node is online.
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