cv2.imshow和cv2.imwrite [英] cv2.imshow and cv2.imwrite

问题描述

有人可以解释为什么OpenCV imshow和imwrite函数似乎导致完全不同的图像吗?

Can someone explain why the OpenCV imshow and imwrite function seem to result in a completely different image?

第一张图片对应于imshow，第二张图片对应于imwrite. Result是一个介于0到255之间的浮点值的数组.

The first picture corresponds to imshow and the second picture corresponds to imwrite. Result is an array of floating point values between 0 and 255.

**result = result.astype(np.uint8)**
cv2.imshow('img', result)
cv2.imwrite('img.png', result)

推荐答案

我在OpenCV 2.4.8中使用了以下(c ++)代码:

I used the following (c++) code with OpenCV 2.4.8:

cv::Mat_<float> img(300,300);
cv::theRNG().fill(img,cv::RNG::UNIFORM,0,255);
cv::imshow("Img",img);
cv::waitKey();
cv::imwrite("test.png",img);

并生成以下图像:

和imshow.

和imwrite.

这是由于两个函数的范围期望不同，imwrite总是期望[0,255]，而imshow期望浮点为[0,1]，而期望[0,255]未签名的字符.

This is due to the different range expectation of the two functions, imwrite always expects [0,255], whereas imshow expects [0,1] for floating point and [0,255] for unsigned chars.

为了用imshow显示正确的输出，您需要将浮点图像的范围从[0,255]减小到[0,1].您可以使用convertTo和适当的缩放比例，或简单地将图片除以255来完成此操作.

In order to display the correct output with imshow, you need to reduce the range of your floating point image from [0,255] to [0,1]. You can do this using convertTo and an appropriate scaling factor, or simply by dividing your image by 255.

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