将浮点数组保存到图像(EXR 格式) [英] Save float array to image (with EXR format)

问题描述

以下代码不起作用，它在将图像写入磁盘之前将值转换为 np.uint8.

The following code does not work, it converts values to np.uint8 before writing image to disk.

import cv2
import numpy as np
# Generate dummy gradient with float values
arr = np.arange(0,10,0.02)
arr = np.repeat(arr, arr.shape[0])
arr.reshape((500,500))
cv2.imwrite('output.exr',arr)
# At this point, returns True. Opening the image with OpenEXR 1.4 shows values have become UINT8 instead of Float
arr = cv2.imread('output.exr')
# Shape is (1000, 1000, 3)
print(arr[10,10])
array([0, 0, 0], dtype=uint8) # All float data is lost

作为一点奖励，文档非常没有帮助

As a little bonus, the documentation is very not helpful

$ pydoc cv2.imwrite
Help on built-in function imwrite in cv2:

cv2.imwrite = imwrite(...)
    imwrite(filename, img[, params]) -> retval

没有说明参数应该是什么...

Doesn't say what the params should be...

如何将带有浮点值的数组保存为 EXR 格式?(使用 OpenCV)

How can I save an array with floating point values to EXR format ? (using OpenCV)

推荐答案

imageio 可以保存 EXR任何数据格式的文件，(它还支持大量其他图像格式).

imageio can save EXR files in any data format, (and it also supports a large amount of other image formats).

读取和写入大多数图像几乎可以挽救生命:

Pretty much a life saver for reading and writing most images:

import numpy as np
import imageio

# Generate dummy random image with float values
arr = np.random.uniform(0.0, 1.0, size=(500,500))

# freeimage lib only supports float32 not float64 arrays
arr = arr.astype("float32")

# Write to disk
imageio.imwrite('float_img.exr', arr)

# Read created exr from disk
img = imageio.imread('float_img.exr')

assert img.dtype == np.float32

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