浮动图片的平均图片 Python

Question

我想做类似这篇文章的事情：sample code。

如何更改给定代码以适用于“tiff”格式的浮动图像？

这是我尝试过的：

import os, numpy, PIL
from PIL import Image

# Access all PNG files in directory
os.chdir("c://users//Student///Desktop//bilder//" )
print "Current working dir : %s" % os.getcwd()

allfiles=os.listdir(os.getcwd())
imlist=[filename for filename in allfiles if  filename[-5:] in [".tiff",".tiff"]]
#imlist=[filename for filename in allfiles]

# Assuming all images are the same size, get dimensions of first image
w,h=Image.open(imlist[0]).size
N=len(imlist)

# Create a numpy array of floats to store the average (assume RGB images)
arr=numpy.zeros((h,w,1),numpy.float)

# Build up average pixel intensities, casting each image as an array of floats
for im in imlist:
    imarr=numpy.array(Image.open(im),dtype=numpy.float)
    arr+=imarr/N

# Round values in array and cast as 8-bit integer
arr=numpy.array(numpy.round(arr),dtype=numpy.uint8)

# Generate, save and preview final image
out=Image.fromarray(arr,mode="F")
out.save("Average.tiff")
out.show()

产生此错误：

File "C:\Users\Student\im_average.py", line 25, in <module>
    arr+=imarr/N
ValueError: non-broadcastable output operand with shape (250,250,1) doesn't match the broadcast shape (250,250,250)

我不熟悉 numpy 数组，所以欢迎任何帮助。

Answer 1

执行 imarr/N 将就地执行并将 dtype 转换为数组的整数。所以，使用 N=float(N)

参考http://docs.scipy.org/doc/numpy/user/basics.indexing.html#assigning-values-to-indexed-arrays

请注意，如果将较高类型分配给较低类型（例如将浮点数分配给整数）甚至是异常（将复数分配给浮点数或整数），分配可能会导致更改。