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Apply Savitzky-Golay filter to an ENVI BIL file
#!/usr/bin/env python
"""
Apply Savitzky-Golay filter to an ENVI BIL file
Uses scipy
http://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.savgol_filter.html
And arsf_envi_reader (available from: https://github.com/pmlrsg/arsf_tools)
Dan Clewley
16/06/2016
"""
from __future__ import print_function
import argparse
from scipy import signal
from arsf_envi_reader import numpy_bin_reader
from arsf_envi_reader import envi_header
POLY_ORDER = 3
WINDOW_SIZE = 7
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument("inputimage", nargs=1,
type=str, help="Input image")
parser.add_argument("outputimage", nargs=1,
type=str, help="Output image")
args = parser.parse_args()
# Open input file
in_data = numpy_bin_reader.BilReader(args.inputimage[0])
# Open file for output
out_file = open(args.outputimage[0], "wb")
for i, line in enumerate(in_data):
print(" Line {0}/{1}".format(str(i).zfill(len(str(in_data.lines))),
in_data.lines), end="\r")
# Apply filter
out_line = signal.savgol_filter(line,
WINDOW_SIZE, POLY_ORDER,
axis=0)
# Remove negative values
out_line[out_line < 0] = 0
# Set output to the same as input
out_line = out_line.astype(line.dtype)
out_line.tofile(out_file)
print(" Line {0}/{0}".format(in_data.lines), end="\n")
# Copy header
envi_header.write_envi_header(args.outputimage[0] + ".hdr",
in_data.get_hdr_dict())
# Close files
out_file.close()
in_data = None
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