python - 将 NumPy 数组转换为 PIL 图像

Question

我想从 NumPy 数组创建一个 PIL 图像。这是我的尝试:

# Create a NumPy array, which has four elements. The top-left should be pure 
# red, the top-right should be pure blue, the bottom-left should be pure green, 
# and the bottom-right should be yellow.
pixels = np.array([[[255, 0, 0], [0, 255, 0]], [[0, 0, 255], [255, 255, 0]]])

# Create a PIL image from the NumPy array
image = Image.fromarray(pixels, 'RGB')

# Print out the pixel values
print image.getpixel((0, 0))
print image.getpixel((0, 1))
print image.getpixel((1, 0))
print image.getpixel((1, 1))

# Save the image
image.save('image.png')

但是，打印输出如下:

(255, 0, 0)
(0, 0, 0)
(0, 0, 0)
(0, 0, 0)

保存的图像左上角是纯红色，但所有其他像素都是黑色的。为什么这些其他像素没有保留我在 NumPy 数组中分配给它们的颜色？

Answer 1

RGB 模式需要 8 位值，因此只需转换数组即可解决问题:

In [25]: image = Image.fromarray(pixels.astype('uint8'), 'RGB')
    ...:
    ...: # Print out the pixel values
    ...: print image.getpixel((0, 0))
    ...: print image.getpixel((0, 1))
    ...: print image.getpixel((1, 0))
    ...: print image.getpixel((1, 1))
    ...:
(255, 0, 0)
(0, 0, 255)
(0, 255, 0)
(255, 255, 0)