Python-handle for LED controller

import ImageGrab
import time
import serial
import ImageGrab
from win32api import GetSystemMetrics

#arduino
# port = 'COM5'
# serial = serial.Serial(port,9600,timeout=0)
# time.sleep(2)
ard = serial.Serial()
def tryPort(com):
    port_name = "COM"+str(com)
    try:
        global ard
        ard = serial.Serial(port_name,9600,timeout=0)
        return True
    except:
        print(port_name+" unavailable")
        return False

def init():
    available = False
    for comPort in range (1,12):
        if tryPort(comPort):
            available = True
            print ("Connection established at COM"+str(comPort)+", please wait.")
            time.sleep(2)
            break
    if available:
        #print ("Testing LEDs... Initializing RGB sequence")
        # flash()
        print ("Everything OK")
        select_region()


def flash():
    ard.flush()
    ard.write("255,0,0X")
    time.sleep(0.5)
    ard.write("0,255,0X")
    time.sleep(0.5)
    ard.write("0,0,255X")
    time.sleep(0.5)
    ard.write("0,0,0X")

active_region = 0
def select_region():
    print("Choose screen region (top/middle/bottom)")
    global active_region
    region = raw_input(">")
    if region=="top": active_region = 500
    elif region=="middle": active_region = h/2
    elif region=="bottom": active_region = h-150
    else: print "No valid region selected, selected middle as default"
    print("Scanning pixels at height: "+str(h-active_region)+" px")



#window
w = GetSystemMetrics(0)
h = GetSystemMetrics(1)
x1 = w/2-w/3
x2 = w/2+w/3

def avg_color():
    image = ImageGrab.grab()
    # print 'width:',w,', height:',h
    r,g,b=0,0,0
    count = 0
    temp_col = "" # used for y-values
    y = active_region
    _range = range(w/2-1000, w/2+1000+1, 400)
    # print(_range)
    for k in _range:
        count+=2
        color = str(image.getpixel((k,y))).translate(None,'() ')
        rgb = color.split(',')
        r+=int(rgb[0])
        g+=int(rgb[1])
        b+=int(rgb[2])
        color = str(image.getpixel((k+200,int(y-y/3)))).translate(None,'() ')
        rgb = color.split(',')
        r+=int(rgb[0])
        g+=int(rgb[1])
        b+=int(rgb[2])
    # output: (r, g, b)->r,g,b
    r,g,b = r/count, g/count, b/count
    # g = int(g*0.75)
    # b = int(b*0.3)
    r = int(r*1.5)
    g= int(g*1.5)
    b = int(b*1.1)

    return str(r)+","+str(g)+","+str(b)+"X"

def main():
    init()
    prev_col = None
    while (True):
        ard.flush()
        col = avg_color()
        if col!=prev_col:
            ard.write(col)
        prev_col = col
        time.sleep(0.45)

main()