调整图像大小时出错：“错误：（-215：声明失败）函数'resize'中的func！= 0” [英] Error while resizing image: "error: (-215:Assertion failed) func != 0 in function 'resize'"

问题描述

我正在尝试将图像数据集重新缩放为（10，10），以numpy数组的形式显示形状为（28，28）的图像。我为此写了一个函数：

I'm trying to preprocess images dataset, represented in numpy array with images of shape (28, 28) by rescaling them to (10, 10). I wrote a function for that:

def resize_dataset(images):
    resized_images = []
    for img in images:
            img = img.reshape((28,28))
            resized_img = cv2.resize(img, dsize=(10, 10))
            resized_images.append(resized_img)
    return numpy.array(resized_images)

但是当我实际上尝试重新缩放它们，我在 cv2.resize 中收到以下错误：

But when I actually try to rescale them, I get the following error in cv2.resize:

error: OpenCV(4.0.0) /io/opencv/modules/imgproc/src/resize.cpp:3662: error: (-215:Assertion failed) func != 0 in function 'resize'

在google中，我只发现在用c ++编写相同的错误的人做非常不同的事情，就像这样：调整图像大小并更改其深度，并且： http://answers.opencv.org/question/19715/error-215-func-0-in-function-convertto /

In google I only found people with the same error writing on c++ doing very different stuff, like this one: resize an image and changing its depth and this: http://answers.opencv.org/question/19715/error-215-func-0-in-function-convertto/

那么，如何解决呢？

推荐答案

<哦，我实际上已经知道了。数据集中的图像类型为 numpy.int64 。我只需要将图像转换为 float32 ，就像这样：

Oh, I actually figured it out. Images in the dataset were of type numpy.int64. I just had to convert images to float32, like this:

def resize_dataset(images):
    resized_images = []
    for img in images:
            img = img.reshape((28,28)).astype('float32')  # <-- convert image to float32
            resized_img = cv2.resize(img, dsize=(10, 10))
            resized_images.append(resized_img)
    return numpy.array(resized_images)

现在它可以很好地工作了。看来 cv2.resize 无法处理以int表示的图像。希望这对任何人都有帮助

And now it works nicely. It looks like cv2.resize can't work with images represented in int. Hope this will help anyone

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