#!/usr/bin/env python

# -*- coding: utf-8 -*-

"""

MODULE: i.fusion.hpf

AUTHOR(S): Nikos Alexandris <nik@nikosalexandris.net>

Converted from a bash shell script | Trikala, Nov. 2014

Panagiotis Mavrogiorgos <pmav99@gmail.com>

Some refactoring | Oct 2015

PURPOSE: HPF Resolution Merge -- Algorithm Replication in GRASS GIS

Module to combine high-resolution panchromatic data with

lower resolution multispectral data, resulting in an output

with both excellent detail and a realistic representation of

original multispectral scene colors.

The process involves a convolution using a High Pass Filter

(HPF) on the high resolution data, then combining this with

the lower resolution multispectral data.

Optionally, a linear histogram matching technique is performed

in a way that matches the resulting Pan-Sharpened imaged to

them statistical mean and standard deviation of the original

multi-spectral image. Credits for how to implement this

technique go to GRASS-GIS developer Moritz Lennert.

Source: "Optimizing the High-Pass Filter Addition Technique for

Image Fusion", Ute G. Gangkofner, Pushkar S. Pradhan,

and Derrold W. Holcomb (2008)

Figure 1:

+-----------------------------------------------------------------------------+

| Pan Img -> High Pass Filter -> HP Img |

| | |

| v |

| MSx Img -> Weighting Factors -> Weighted HP Img |

| | | |

| | v |

| +------------------------> Addition to MSx Img => Fused MSx Image |

+-----------------------------------------------------------------------------+

COPYRIGHT: (C) 2014 - 2015 by the GRASS Development Team

This program is free software under the GNU General Public

License (>=v2). Read the file COPYING that comes with GRASS

for details.

"""

#%Module

#% description: Fusing high resolution Panchromatic and low resolution Multi-Spectral data based on the High-Pass Filter Addition technique (Gangkofner, 2008)

#% keywords: imagery

#% keywords: fusion

#% keywords: sharpening

#% keywords: high pass filter

#% keywords: HPFA

#%End

#%flag

#% key: l

#% description: Linearly match histogram of Pan-sharpened output to Multi-Spectral input

#%end

#%flag

#% key: 2

#% description: 2-Pass Processing (recommended) for large resolution ratio (>=5.5)

#%end

#%flag

#% key: c

#% description: Match color table of Pan-Sharpened output to Multi-Spectral input

#%end

#%option G_OPT_R_INPUT

#% key: pan

#% key_desc: filename

#% description: High resolution Panchromatic image

#% required : yes

#%end

#%option G_OPT_R_INPUTS

#% key: msx

#% key_desc: filename(s)

#% description: Low resolution Multi-Spectral image(s)

#% required: yes

#% multiple: yes

#%end

#%option G_OPT_R_BASENAME_OUTPUT

#% key: suffix

#% key_desc: suffix string

#% type: string

#% label: Suffix for output image(s)

#% description: Names of Pan-Sharpened image(s) will end with this suffix

#% required: yes

#% answer: hpf

#%end

#%option

#% key: ratio

#% key_desc: rational number

#% type: double

#% label: Custom ratio

#% description: Custom ratio overriding standard calculation

#% options: 1.0-10.0

#% guisection: High Pass Filter

#% required: no

#%end

#%option

#% key: center

#% key_desc: string

#% type: string

#% label: Center cell value

#% description: Center cell value of the High-Pass-Filter

#% descriptions: Level of center value (low, mid, high)

#% options: low,mid,high

#% required: no

#% answer: low

#% guisection: High Pass Filter

#% multiple : no

#%end

#%option

#% key: center2

#% key_desc: string

#% type: string

#% label: 2nd Pass center cell value

#% description: Center cell value for the second High-Pass-Filter (use -2 flag)

#% descriptions: Level of center value for second pass

#% options: low,mid,high

#% required: no

#% answer: low

#% guisection: High Pass Filter

#% multiple : no

#%end

#%option

#% key: modulation

#% key_desc: string

#% type: string

#% label: Modulation level

#% description: Modulation level weighting the HPF image determining crispness

#% descriptions: Levels of modulating factors

#% options: min,mid,max

#% required: no

#% answer: mid

#% guisection: Crispness

#% multiple : no

#%end

#%option

#% key: modulation2

#% key_desc: string

#% type: string

#% label: 2nd Pass modulation level (use -2 flag)

#% description: Modulation level weighting the second HPF image determining crispness (use -2 flag)

#% descriptions: mid;Mid: 0.35;min;Minimum: 0.25;max;Maximum: 0.5;

#% options: min,mid,max

#% required: no

#% answer: mid

#% guisection: Crispness

#% multiple : no

#%end

#%option

#% key: trim

#% key_desc: rational number

#% type: double

#% label: Trimming factor

#% description: Trim output border pixels by a factor of the pixel size of the low resolution image. A factor of 1.0 may suffice.

#% guisection: High Pass Filter

#% required: no

#%end

# StdLib

import os

import sys

import atexit

# check if within a GRASS session?

if "GISBASE" not in os.environ:

print "You must be in GRASS GIS to run this program."

sys.exit(1)

# PyGRASS

import grass.script as grass

from grass.pygrass.modules.shortcuts import general as g

from grass.pygrass.raster.abstract import Info

from grass.pygrass.utils import get_lib_path

# add "etc" directory to $PATH

path = get_lib_path("i.fusion.hpf", "")

if path is None:

raise ImportError("Not able to find the path %s directory." % path)

sys.path.append(path)

# import modules from "etc"

from high_pass_filter import get_high_pass_filter, get_modulator_factor, get_modulator_factor2

def run(cmd, **kwargs):

"""Pass arbitrary number of key-word arguments to grass commands and the

"quiet" flag by default."""

grass.run_command(cmd, quiet=True, **kwargs)

def cleanup():

"""Clean up temporary maps"""

pattern = 'tmp.{pid}*'.format(pid=os.getpid())

run('g.remove', flags="f", type="raster", pattern=pattern)

def avg(img):

return avg

def stddev(img):

return sd

def hpf_weight(low_sd, hpf_sd, mod, pss):

return wgt

def hpf_ascii(center, filter, tmpfile, second_pass):

asciif.write(filter)

# main program

def main():

flags='i')

if __name__ == "__main__":

options, flags = grass.parser()

atexit.register(cleanup)

sys.exit(main())