我有一个Numpy数组类型的矩阵。我怎么把它作为映像写到磁盘上呢?任何格式都可以(png, jpeg, bmp…)一个重要的限制是PIL不存在。


当前回答

你可以使用这段代码将你的Npy数据转换成图像:

from PIL import Image
import numpy as np
data = np.load('/kaggle/input/objects-dataset/nmbu.npy')
im = Image.fromarray(data, 'RGB')
im.save("your_file.jpeg")

其他回答

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)

对于那些寻找一个直接的充分工作的例子:

from PIL import Image
import numpy

w,h = 200,100
img = numpy.zeros((h,w,3),dtype=numpy.uint8) # has to be unsigned bytes

img[:] = (0,0,255) # fill blue

x,y = 40,20
img[y:y+30, x:x+50] = (255,0,0) # 50x30 red box

Image.fromarray(img).convert("RGB").save("art.png") # don't need to convert

此外,如果你想要高质量的jpeg .save(file, subsampling=0, quality=100)

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  

@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。)

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.