#!/bin/bash

# Create a VIIRS M-band quicklook image
# Liam.Gumley@ssec.wisc.edu 2012/03/12

# Check arguments
if [ $# -eq 0 ]; then
  echo "Usage: viirs_quicklook.bash band file1 file2 file3 ..."
  exit 1
fi

# Get band number
band=$1
shift

# Get list of files and number of files
list=$@
count=$#

# Set dataset name
visible='yes'
dataset='/All_Data/VIIRS-M'$band'-SDR_All/Reflectance'
if [ $band -ge 12 ]; then
  visible='no'
  dataset='/All_Data/VIIRS-M'$band'-SDR_All/BrightnessTemperature'
fi

# Build a 16-bit grayscale array of image data
for file in $list; do
  h5dump -d $dataset -b LE -o temp_image.dat $file
  cat temp_image.dat >> temp_image.gray
done
rm -f temp_image.dat

# Get image dimensions (width and height)
size=$(stat -c "%s" temp_image.gray)
width=3200
height=$(echo "($size/2)/$width" | bc)

# Set output file name
header=$(basename $1 | cut -d_ -f 1-4)
etime=$(basename $file | cut -d_ -f 5)
out_file=$header"_"$etime.png

# Convert the 16-bit grayscale array to a PNG image
if [ "$visible" == "yes" ]; then
  convert -size ${width}x${height} -depth 16 -equalize -geometry 20% -rotate 180 temp_image.gray $out_file
else
  convert -size ${width}x${height} -depth 16 -negate -equalize -geometry 20% -rotate 180 temp_image.gray $out_file
fi
rm -f temp_image.gray
echo "Created "$out_file

exit 0