一个答案使用PIL(只是在情况下它是有用的)。

给定一个numpy数组" a ":

from PIL import Image
im = Image.fromarray(A)
im.save("your_file.jpeg")

你可以用几乎任何你想要的格式替换“jpeg”。更多关于格式的细节请点击这里

matplotlib:

import matplotlib.image

matplotlib.image.imsave('name.png', array)

适用于matplotlib 1.3.1，我不知道低版本。从文档字符串:

Arguments:
  *fname*:
    A string containing a path to a filename, or a Python file-like object.
    If *format* is *None* and *fname* is a string, the output
    format is deduced from the extension of the filename.
  *arr*:
    An MxN (luminance), MxNx3 (RGB) or MxNx4 (RGBA) array.

使用cv2.imwrite。

import cv2
assert mat.shape[2] == 1 or mat.shape[2] == 3, 'the third dim should be channel'
cv2.imwrite(path, mat) # note the form of data should be height - width - channel  

Matplotlib SVN有一个新函数，可以将图像保存为图像-没有轴等，这是一个非常简单的函数，如果你不想安装SVN(直接从Matplotlib SVN中的image.py复制，为了简洁，删除了文档字符串):

def imsave(fname, arr, vmin=None, vmax=None, cmap=None, format=None, origin=None):
    from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
    from matplotlib.figure import Figure

    fig = Figure(figsize=arr.shape[::-1], dpi=1, frameon=False)
    canvas = FigureCanvas(fig)
    fig.figimage(arr, cmap=cmap, vmin=vmin, vmax=vmax, origin=origin)
    fig.savefig(fname, dpi=1, format=format)

scipy。Misc给出关于imsave函数的弃用警告，并建议使用imageio代替。

import imageio
imageio.imwrite('image_name.png', img)

@ideasman42回答的附录:

def saveAsPNG(array, filename):
    import struct
    if any([len(row) != len(array[0]) for row in array]):
        raise ValueError, "Array should have elements of equal size"

                                #First row becomes top row of image.
    flat = []; map(flat.extend, reversed(array))
                                 #Big-endian, unsigned 32-byte integer.
    buf = b''.join([struct.pack('>I', ((0xffFFff & i32)<<8)|(i32>>24) )
                    for i32 in flat])   #Rotate from ARGB to RGBA.

    data = write_png(buf, len(array[0]), len(array))
    f = open(filename, 'wb')
    f.write(data)
    f.close()

所以你可以这样做:

saveAsPNG([[0xffFF0000, 0xffFFFF00],
           [0xff00aa77, 0xff333333]], 'test_grid.png')

生产test_grid.png:

(透明性也可以通过减少0xff的高字节来工作。)