PIL 类型错误: 无法处理此数据类型

我有一个图像存储在一个数字数组，我想转换为 PIL.Image，以执行插值只有 PIL 可用。

当试图通过 Image.fromarray()转换它时，会产生以下错误:

TypeError: 无法处理此数据类型

我已经阅读了 给你和 给你的答案，但他们似乎没有帮助我的情况。

我想说的是:

from PIL import Image


x  # a numpy array representing an image, shape: (256, 256, 3)


Image.fromarray(x)
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最佳答案

tl;dr

Does x contain uint values in [0, 255]? If not and especially if x ranges from 0 to 1, that is the reason for the error.

Explanation

Most image libraries (e.g. matplotlib, opencv, scikit-image) have two ways of representing images:

  • as uint with values ranging from 0 to 255.
  • as float with values ranging from 0 to 1.

The latter is more convenient when performing operations between images and thus is more popular in the field of Computer Vision. However PIL seems to not support it for RGB images.

If you take a look here it seems that when you try to read an image from an array, if the array has a shape of (height, width, 3) it automatically assumes it's an RGB image and expects it to have a ABC1 of uint8! In your case, however, you have an RBG image with float values from 0 to 1.

Solution

You can fix it by converting your image to the format expected by PIL:

im = Image.fromarray((x * 255).astype(np.uint8))
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I solved it different way.

Problem Situation: When working with gray image or binary image, if the numpy array shape is (height, width, 1), this error will be raised also.
For example, a 32 by 32 pixel gray image (value 0 to 255)

np_img = np.random.randint(low=0, high=255, size=(32, 32, 1), dtype=np.uint8)
# np_img.shape == (32, 32, 1)
pil_img = Image.fromarray(np_img)

will raise TypeError: Cannot handle this data type: (1, 1, 1), |u1

Solution:

If the image shape is like (32, 32, 1), reduce dimension into (32, 32)

np_img = np.squeeze(np_img, axis=2)  # axis=2 is channel dimension
pil_img = Image.fromarray(np_img)

This time it works!!

Additionally, please make sure the dtype is uint8(for gray) or bool(for binary).

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I found a different issue for the same error in my case. The image I used was in RGBA format, so before using fromarray() function just convert it to RGB using the convert() function and it will work perfectly fine.

image_file = Image.open(image_file)
image_file = image_file.convert('RGB')

P.S.: Posting this solution as an initial step, before converting the image to np.

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In my case file format of the images was changed to png to jpg. It worked well when I corrected the image format of the error images.

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In my case it was only because I forgotted to add the "RGB" arg in the "fromarray" func.

pil_img = Image.fromarray(np_img, 'RGB')

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