#!/bin/env python
# encoding: utf-8

import pyfits
from optparse import OptionParser

import numpy
from scipy import *

parser = OptionParser()

(options, args) = parser.parse_args ()

if (len(args) != 2):
    print "Usage : suppr_fond.py input.fits output.fits"
    exit(1)

# E# Ouverture de l'image fits en argument
hdulist = pyfits.open(args[0])
scidata = hdulist[0].data

if (scidata.shape != (2048,2048)):
    print "Erreur ! l'image ne fait pas 2048 x 2048 !"
    exit(2)

# Estimation fond (4 coins)
tf = 256 # taille fenetre fond, en pix
fond_bas = .5 * (mean(scidata[:tf,:tf]) + mean(scidata[:tf,2048-tf:]))
fond_haut= .5 * (mean(scidata[2048-tf:,:tf]) + mean(scidata[2048-tf:,2048-tf:]))

a = float(fond_haut - fond_bas) / (2048-tf)
b = fond_haut - a * (2048 - tf/2.)

fond=numpy.zeros((2048,2048))

for i in range(2048):
    fond[i,:] = a * i + b


scidata -= fond

prihdr = hdulist[0].header
prihdr.add_history('Suppression fond gradient vertical')

hdulist[0].data = scidata
hdulist.writeto(args[1],clobber=True)


hdulist.close()