python——测量像素亮度

Question

如何测量图像中特定像素的像素亮度？我正在寻找用于比较不同像素亮度的绝对比例。谢谢

Answer 1

要获取像素的 RGB 值，您可以使用 PIL :

from PIL import Image
from math import sqrt
imag = Image.open("yourimage.yourextension")
#Convert the image te RGB if it is a .gif for example
imag = imag.convert ('RGB')
#coordinates of the pixel
X,Y = 0,0
#Get RGB
pixelRGB = imag.getpixel((X,Y))
R,G,B = pixelRGB 

然后，亮度只是一个从黑到白的刻度，如果对三个 RGB 值进行平均就可以提取亮度:

brightness = sum([R,G,B])/3 ##0 is dark (black) and 255 is bright (white)

或者您可以更深入地使用 Ignacio Vazquez-Abrams 评论的亮度公式:( Formula to determine brightness of RGB color )

#Standard
LuminanceA = (0.2126*R) + (0.7152*G) + (0.0722*B)
#Percieved A
LuminanceB = (0.299*R + 0.587*G + 0.114*B)
#Perceived B, slower to calculate
LuminanceC = sqrt(0.299*(R**2) + 0.587*(G**2) + 0.114*(B**2))