#----------------------------------------------------------------------
# Introduction to image processing
#
# Copyright (C) October 2, 2017 -- Dr. William T. Verts
#----------------------------------------------------------------------

#----------------------------------------------------------------------
# Brighten an image by amount input by user (amount can be negative)
#----------------------------------------------------------------------

def Main():
    Filename = pickAFile()
    print Filename
    Canvas = makePicture(Filename)
    show(Canvas)
    W = getWidth(Canvas)
    H = getHeight(Canvas)
    print "Width = ", W
    print "Height = ", H
    Amount = input("Enter Brightness Offset --- ")
    for Y in range(H):
        for X in range(W):
            PX = getPixel(Canvas,X,Y)
            setRed(PX,getRed(PX) + Amount)
            setGreen(PX,getGreen(PX) + Amount)
            setBlue(PX,getBlue(PX) + Amount)
        repaint(Canvas)
    return

#----------------------------------------------------------------------
# Brighten only the dark pixels in an image
#----------------------------------------------------------------------

def Main2():
    Filename = pickAFile()
    print Filename
    Canvas = makePicture(Filename)
    show(Canvas)
    W = getWidth(Canvas)
    H = getHeight(Canvas)
    print "Width = ", W
    print "Height = ", H
    Amount = input("Enter Brightness Offset --- ")
    for Y in range(H):
        for X in range(W):
            PX = getPixel(Canvas,X,Y)
            # Do something funky here with red, green, and blue
            Brightness = (getRed(PX) + getGreen(PX) + getBlue(PX)) / 3
            if (Brightness < 128):
                setRed(PX,getRed(PX) + Amount)
                setGreen(PX,getGreen(PX) + Amount)
                setBlue(PX,getBlue(PX) + Amount)
                
        repaint(Canvas)
    return
        
#----------------------------------------------------------------------
# Make an image B&W.  Brightness threshold can be changed.
#----------------------------------------------------------------------

def Main3():
    Filename = pickAFile()
    print Filename
    Canvas = makePicture(Filename)
    show(Canvas)
    W = getWidth(Canvas)
    H = getHeight(Canvas)
    print "Width = ", W
    print "Height = ", H
    for Y in range(H):
        for X in range(W):
            PX = getPixel(Canvas,X,Y)
            # Do something funky here with red, green, and blue
            Brightness = (getRed(PX) + getGreen(PX) + getBlue(PX)) / 3
            if (Brightness < 96):
                setRed(PX,0)
                setGreen(PX,0)
                setBlue(PX,0)
            else:
                setRed(PX,255)
                setGreen(PX,255)
                setBlue(PX,255)
                
        repaint(Canvas)
    return