'''
<!-- UW-Madison CIMSS GOES16 True color RGB(Natural) Header
         True color RGB (Green like component) satellite-derived parameter definition file.
    -->
    <!-- GOES16 True color RGB
	 This defines the UW-Madison CIMSS GOES16 true color RGB(NAatural) for AWIPS-II, created on the fly.
         This is achieved by calling the Python method called CIMSSGOES16RGBNaturalBeta, following the UW-Madison CIMSS
         green channel generation as described in the paper: "How to Generate GOES-16 TRUE COLOR RGB images" The three above mentioned 
         channels gets passed in to the method through the "field abbreviation", These are then combined and or enhanced
         to return a green like band. The "ConstantFields" are described in the method function
         "CIMSSmakeGoes16GreenBandBeta".
    -->
<!-- GOES16 True color RGB(Natural) Status
	This is a new derived parameter set of files designed to Make GOES-16 True color RGB images on the fly and currently
        not included in the AWIPS 2 baseline.
-->
  <!-- GOES16 True color RGB POC
         Kaba Bah
    -->

CONTACTS: 

	This code was developed at UW Madison CIMSS for generating GOES-16 true color RGB images on the fly,
        It required no additional information besides the already existing first three GOES16 ABI channels.
        The green band gets generated on the fly and the enhancements applied do not require and further information:

		Algorithm was developed by Kaba Bah at UW-Madison CIMSS.
                 Kaba Bah: (kbah@ssec.wisc.edu),Ph:608-262-4462

INPUT PARAMETERS:
        All inputs are expected to be 8bit for theIS Beta version.
 	
    @param physicalElement1: 
		GOES16 ABI band01 (0.47um) data.

 	@param physicalElement2:
		GOES16 ABI band02 (0.64um) data.
 
 	@param physicalElement3:
		GOES16 ABI band03 (0.87um) data.

    @param bnum:
		The band number. (0=blue, 1=red, 2=green)
		
 	@param minValue:
		The expected minimum value for the returned array

 	@param maxValue:
		The expected maximum value for the returned array
 	@param gamma:
		Gamma value used for stretching. (0=n0, 1=yes)


RETURNS:

 	@return: Display values
 	@rtype: numpy array (int12)

DEPENDENCIES:

	* Numpy


MODIFICATIONS:

'''
	
import numpy as np

def execute(physicalElement1, physicalElement2, physicalElement3, bnum, minValue, maxValue, gamma):
    
	#########################
	# Make Green band on the fly is makeGreen=1.
	if (int(bnum) == 1):
		aband	= 2.5*physicalElement1
	if (int(bnum) == 2):
		aband	= 2.5*physicalElement2  
        if (int(bnum) == 3):
		#Make Green band on the fly.
		aband	= 2.5*(0.45*physicalElement1 + 0.45*physicalElement2 + 0.10*physicalElement3) 


	#########################
	# Convert data to 0.0 t0 1.0 for use in generating a SQRT enhancement.
	aband0 =(aband/255.0) 

	#########################

	# Apply a simple sqrt following UW-CIMSS True color RGB (for Natural color).
	aband = (np.sqrt(aband0)*255.0)
      
        ####################################
        #### Apply a simple contrast adjustment enhancement
        #acont=maxValue/10.0
        #amax=maxValue+4 
        #amid=maxValue/2.0
        acont=255.0/10.0
        amax=255.0+4 
        amid=255.0/2.0
        afact=(amax*(acont+maxValue)/(maxValue*(amax-acont)))
        aband = (afact*(aband-amid)+amid)
        aband[aband <= 10] = 0
        aband[aband >=255] = 255

	#########################
	# Convert from float to in8.
	dispByte = np.array(aband, dtype=np.int8)

	#########################
	# Convert values of 0 to 1.
	dispByte[dispByte == 0] = 255

	#########################
	#mask out of range values
	dispByte[(aband == 0)] = 0

	return dispByte