调整图像大小而不会变形OpenCV

Question

我正在使用python 3和最新版本的openCV。我正在尝试使用提供的调整大小功能来调整图像大小，但是调整图像大小后会非常失真。代码：

import cv2
file = "/home/tanmay/Desktop/test_image.png"
img = cv2.imread(file , 0)
print(img.shape)
cv2.imshow('img' , img)
k = cv2.waitKey(0)
if k == 27:
    cv2.destroyWindow('img')
resize_img = cv2.resize(img  , (28 , 28))
cv2.imshow('img' , resize_img)
x = cv2.waitKey(0)
if x == 27:
    cv2.destroyWindow('img')

原始图像为480 x 640（RGB，因此我将0传递给它来达到灰度）

有什么办法可以调整大小并避免使用OpenCV或任何其他库造成的失真？我打算制作一个手写数字识别器，并且已经使用MNIST数据训练了我的神经网络，因此我需要图像为28x28。

Answer 1

您可以在下面尝试。该功能将保持原始图像的宽高比。

def image_resize(image, width = None, height = None, inter = cv2.INTER_AREA):
    # initialize the dimensions of the image to be resized and
    # grab the image size
    dim = None
    (h, w) = image.shape[:2]

    # if both the width and height are None, then return the
    # original image
    if width is None and height is None:
        return image

    # check to see if the width is None
    if width is None:
        # calculate the ratio of the height and construct the
        # dimensions
        r = height / float(h)
        dim = (int(w * r), height)

    # otherwise, the height is None
    else:
        # calculate the ratio of the width and construct the
        # dimensions
        r = width / float(w)
        dim = (width, int(h * r))

    # resize the image
    resized = cv2.resize(image, dim, interpolation = inter)

    # return the resized image
    return resized

这是一个示例用法。

image = image_resize(image, height = 800)

希望这可以帮助。