• process_fits

PROCESS_FITS

Description

Process_fits is the main ingestion program for SPC, specifically adjusted to support OREx's metadata and file format. It does the following:

• reads a FITS image file
• extracts relevant information from the header

• adds a record to the make_sumfiles.in file

• adds a raw 16- bit unsigned integer image to the IMAGEFILES directory

SPC-OREx Naming Convention - FITS filenames are shortened to 12 characters. The 1st char and last two chars have embedded metadata in them. This explains how Bob encoded it. In general, it is camera symbol (P,M,N,T), the ET and then two char for filter number and processing status.

Level 0

The data stored in each image file contained in the IMAGEFILES directory is a scaled unsigned integer (as 14 bits folded into 16 bits), with the exclusion of values less than 0. Acceptable values are from 0 to 16,383 (14 bit). The files will contain a bias -- i.e. an offset to ensure that the system can record no-photons detected without needing to use a negative value (in all flight conditions and temperatures)

ECR Changes from 3.0A2

• Support OREx level 0 images
  • Trim the second channel from the image to make it 1024x1024
  • Remove dark/bias -- This comes from the shielded overscan region
  • Correct the flat field
  • Desmear the image

Additional Required Files

• DATA/DN2TEMP.TXT

• DATA/FLATFILES.TXT

Outputs

• a row for the image is appended to make_sumfiles.in

• 16-bit unsigned integer image(s) are stored to IMAGEFILES directory. Stretched from 0 to 65536

WARNING

• The program display will put the 0,0 position of the image in the top left, but OREx wants 0,0 to be in the bottom left.

Level 0 Processing Steps

The level 0 OCAMS and NavCam images need to have a basic level of calibration done to them, which occurs in process_fits. The details of the calibration comes from the following documents

OCAMS

Level 0 OCAMS images have the images stored as two FITS images. The first FITS image is the standard 1024x1024 FITS image that most of the science team will use (if they want level 0). The second FITS image array is 1111 x 1043, which is the full sensor for OCAMS and contains the overscan region used for calibration. This format is fully described in the OCAMS SIS.

These keywords are read by SPC, FITS Keywords and describes what is done with each.

1. DN2TEMP.
   1. OCAMS thermoresitors DNs are converted into physical units using the OCAMS Flight Software Engineer Dictionary (OREX-DOC-05.01-00259, Rev_C, Dated 12/04/2015) for SPC v3.0.1.

   2. SPC uses the 4 weighting parameters in DN2TEMP.TXT to calculate a linear weighted value for the effective temperature of the camera optics. For testing, we are weighting each thermoresistor by .25, providing each one with equal weight.

   3. The OCAMS Instrument Team will provide the final weighting during operations. There is no ICD or SIS for the information, so it will have to be done via email and documented as a memo.
2. Reduce Size. SPC will read the 2nd image of the file, which includes the overscan regions. It will take the main 1024x1024 pixels for the image DN, loading the other portions into Flat and Dark variables for calibration. If the label doesn't match the image, it will output "INCONSISTENCY" otherwise, it will show "OKAY".
3. FLATFILES.TXT - Scale and divide
4. Darks - Subtract

TAGCAMS (NavCam / NFTCam)

FITS Keywords The following keywords are read by SPC. This describes what is done with each.

• 1) DN2TEMP - Using DN2TEMP.TXT, apply the polynomial coefficients to convert from DN to a temperature in C. The format is temp = C1 * DN^{3 + C2 * DN}2 + C3 * DN + C4 2) Reduce Size - Remove the black borders on the NavCam/NFTCam images 3) Darks

  •     DN(i,j) -= DK(i,j)

  4) FLATFILES.TXT

  •     DN (i,j) *= FLAT(i,j)

Level 1

If the source is a real (or 32-bit float) value process_fits takes the original images' data float and calculates the maximum value. Then it scales the data to spread from 0 to 65536 to maximize the accuracy of the stored data.

These keywords are read by SPC, FITS Keywords and describes what is done with each.

Required Files

• FITS image file - You provide the name as part of the standard input.

• INIT_LITHOS.TXT - Contains SPICE kernels. Each line entry that contains PCK= will have the spice command furnish run on it. SPC expects the leap second kernel to be defined in this list (which is also defined in make_sumfiles.txt).

Outputs

• A row for the image is appended to make_sumfiles.in

• 16-bit unsigned integer image(s) are stored to IMAGEFILES directory. Stretched from 0 to 65536

Using process_fits

process_fits can be run in two modes

• Single file - just give the FITS filename at the prompt
• Batch mode

  • If the file newpic.txt exists, then process_fits will search through ../OSIRIS_REX/NEW_IMAGES to find the image and process. NEW_IMAGES is configured as YYYY/DOY/<source images>.

  • Note, the built-in search only goes from 2015 to 2022 directories.
  • The files don't actually have to be in the correct directories, it is just good practice for organization. SPC will search all directories from 2015/001 to 2022/365.

Here is a sample of the standard input:

 Input filename
2019-01-20T22-47-05.541_PCAM_L0b_V004.fits
 OKAY
2019 JAN 20 22:47:05.050
EXPOSURE(ms) =    100.000
 MSB SIGNED
      0.00      0.00      0.00      0.00      0.00
   5.0000000000000000
P601296494J3

Old - process_fits-3.0A2

(Compiled by EP)

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