noStroke()
colorMode(RGB, 100)
for i in range(100): 
    for j in range(100): 
        stroke(i, j, 0)
        point(i, j)

noStroke()
colorMode(HSB, 100)
for i in range(100): 
    for j in range(100): 
        stroke(i, j, 100)
        point(i, j)

# If the color is defined here, it won't be 
# affected by the colorMode() in setup(). 
# Instead, just declare the variable here and 
# assign the value after the colorMode() in setup()
#bg = color(180, 50, 50) # No

def setup():
    size(100, 100)
    colorMode(HSB, 360, 100, 100)
    global bg
    bg = color(180, 50, 50)

def draw(): 
    background(bg)