python - 如何打印出一张图片的平均像素？

Question

我的代码如下，我想通过使用 PIL 中的 .averagePixels 代码打印出平均像素，但输出返回“int”对象不可迭代。任何人都可以帮忙

from PIL import Image
class PixelCounter(object):
    def __init__(self, imageName):
        self.pic = Image.open(imageName)
        self.imgData = self.pic.load()
    def averagePixels(self):
        r, g, b = 0, 0, 0
        count = 0
        for x in range(self.pic.size[0]):
            for y in range(self.pic.size[1]):
                tempr,tempg,clrs = self.imgData[x,y]
                r += clrs[0]
                g += clrs[1]
                b += clrs[2]
                count += 1
        yield ((r/count)(g/count),(b/count), count)

if __name__ == '__main__':

    x=[]

    pc = PixelCounter(r"C:\Users\lena-gs.png")
    print ("(red, green, blue, total_pixel_count)")
    print (list(pc.averagePixels()))

输出是:

 (red, green, blue, total_pixel_count)
 TypeError  Traceback (most recent call last)
 <ipython-input-121-4b7fee4299ad> in <module>()
 19     pc = PixelCounter(r"C:\Users\user\Desktop\lena-gs.png")
 20     print ("(red, green, blue, total_pixel_count)")
 ---> 21     print (list(pc.averagePixels()))
 22 
 23 

 <ipython-input-121-4b7fee4299ad> in averagePixels(self)
  9         for x in range(self.pic.size[0]):
 10             for y in range(self.pic.size[1]):
 ---> 11                 tempr,tempg,clrs = self.imgData[x,y]
 12                 r += clrs[0]
 13                 g += clrs[1]

 TypeError: 'int' object is not iterable

Answer 1

发生这种情况是因为 self.imgData[x, y] 是一个 int，而不是可以解压缩为三个变量的东西；也就是说，如果您尝试执行诸如 a, b, c = 2 之类的操作，则会出现相同的错误。由于您的图像名为 lena-gs.png，我想这可能会发生，因为您使用的是没有 Alpha channel 的灰度图像:

In [16]: pic = Image.open('test.png')

In [17]: data = pic.load()

In [18]: data[0, 0]
Out[18]: (44, 83, 140, 255)

In [19]: pic = Image.open('test-grayscale-with-alpha.png')

In [20]: data = pic.load()

In [21]: data[0, 0]
Out[21]: (92, 255)

In [33]: pic = Image.open('test-grayscale-without-alpha.png')

In [35]: data = pic.load()

In [36]: data[0, 0]
Out[36]: 92