使用 OpenCV Python 调整图像大小的最佳方法

Question

我想根据百分比调整图像大小，并使其尽可能接近原始图像，同时尽量减少噪点和失真。调整大小可以向上或向下，因为我可以缩放到原始图像大小的 5% 或 500%（或作为示例给出的任何其他值）

这是我尝试过的，我需要对调整后的图像进行绝对最小的更改，因为我将使用它与其他图像进行比较

def resizing(main,percentage):
    main = cv2.imread(main)
    height = main.shape[ 0] * percentage
    width = crop.shape[ 1] * percentage
    dim = (width,height)
    final_im = cv2.resize(main, dim, interpolation = cv2.INTER_AREA)
    cv2.imwrite("C:\\Users\\me\\nature.jpg", final_im)

Answer 1

我认为您正在尝试调整大小并保持纵横比。这是一个根据百分比放大或缩小图像的函数

原图示例

将图像大小调整为 0.5 (50%)

将图像大小调整为 1.3 (130%)

import cv2

# Resizes a image and maintains aspect ratio
def maintain_aspect_ratio_resize(image, width=None, height=None, inter=cv2.INTER_AREA):
    # Grab the image size and initialize dimensions
    dim = None
    (h, w) = image.shape[:2]

    # Return original image if no need to resize
    if width is None and height is None:
        return image

    # We are resizing height if 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)
    # We are resizing width if height is none
    else:
        # Calculate the ratio of the width and construct the dimensions
        r = width / float(w)
        dim = (width, int(h * r))

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

if __name__ == '__main__':
    image = cv2.imread('1.png')
    cv2.imshow('image', image)
    resize_ratio = 1.2
    resized = maintain_aspect_ratio_resize(image, width=int(image.shape[1] * resize_ratio))
    cv2.imshow('resized', resized)
    cv2.imwrite('resized.png', resized)
    cv2.waitKey(0)

Answer 2

你可以使用cv2.resize这个语法：

  cv2.resize(image,None,fx=int or float,fy=int or float)

fx 取决于宽度

fy 取决于高度

你可以把第二个参数None或(0,0)

例子：

  img = cv2.resize(oriimg,None,fx=0.5,fy=0.5)

注意：

0.5 表示要缩放图像的 50%