Data Set Overview
This data set contains products acquired by the JunoCam
This data set uses the Committee on Data Management
and Computation (CODMAC) data level numbering system.
The JunoCam RDRs are considered Level 3 or Calibrated
Data (equivalent to NASA Level 1A). The RDRs are corrected
for instrument signature and converted to scaled radiance.
JunoCam products are produced by the junomakepds.py program from
the format internally used at the JunoCam Mission Operations
Facility (MOF). This program reads a JunoCam image file, extracts
information from its headers, formats and attaches the PDS labels,
and appends the image data.
The RDR is produced by inverting the onboard 12-to-8-bit companding
to yield linear data numbers of detector response. A flat field
correction would also be done at this step, but this is not currently
implemented as the instrument response is fairly uniform without it.
For planetary targets these values are then scaled such that a white
surface at the solar distance at the time of imaging and with the
commanded exposure time would have a pixel value of 10,000 data
For images of a black sky, however, this would result in a loss of
dynamic range, since most pixel values would collapse to 1 or 2 data
numbers. Therefore, for such images the RDR values simply represent
the number of electrons at each pixel. Since the detector's full
well capacity is about 30,000 electrons of signal, this value can be
represented as a 16-bit integer.
All JunoCam images must be a multiple of 16 pixels in both width
and height. Images are broken up into subimages (also called
fragments), and each fragment is transmitted separately. Raw and
predictively compressed images are reconstructed by concatenating
all of their image fragments and then processing; transform
compressed images are processed a fragment at a time. A JunoCam
data product consists of one image with decompression applied.
For each image file, a header identifies various properties of
the image and contains a file offset to the data portion of the
image. The image data are then appended to the end of the file.
Refer to the JunoCam Experiment Data Record (EDR) and Reduced Data
Record (RDR) PDS Data Products Software Interface Specification (SIS)
for further details on the JunoCam data products.