def luminance(pixel):
"""
Returns the luminance of a pixel, which indicates its subjective
brightness. This implementation uses the NTSC formula.
"""
r = GImage.getRed(pixel)
g = GImage.getGreen(pixel)
b = GImage.getBlue(pixel)
return round(0.299 * r + 0.587 * g + 0.114 * b)
def greenScreen(old, new):
old_array = old.getPixelArray()
new_array = new.getPixelArray()
for col in range(len(old_array)):
for row in range(len(old_array[0])):
if col < len(new_array) and row < len(new_array[0]):
pixel = new_array[col][row]
max_rb = max(GImage.getRed(pixel), GImage.getBlue(pixel))
green = GImage.getGreen(pixel)
if green < 2 * max_rb:
old_array[col][row] = pixel
return GImage(old_array)
def isntGreen(pixel):
r = GImage.getRed(pixel)
g = GImage.getGreen(pixel)
b = GImage.getBlue(pixel)
if r >= b:
maxRB = r
else:
maxRB = b
if g > 2 * maxRB:
return False
else:
return True
def posterize(image):
array = image.getPixelArray()
for col in range(len(array)):
for row in range(len(array[0])):
pixel = array[col][row]
red = GImage.getRed(pixel)
green = GImage.getGreen(pixel)
blue = GImage.getBlue(pixel)
d_min = 500**2
for i in range(len(PALETTE)):
pre_red = PALETTE[i][0]
pre_green = PALETTE[i][1]
pre_blue = PALETTE[i][2]
d = ((2 * (pre_red - red)**2) + (4 * (pre_green - green)**2) +
(3 * (pre_blue - blue)**2) +
((((pre_red + red) / 2) * ((pre_red - red)**2) -
((pre_blue - blue)**2)) / 256))
if d < d_min:
d_min = d
new_pixel = GImage.createRGBPixel(pre_red, pre_green,
pre_blue)
array[col][row] = new_pixel
return GImage(array)
