Python cv2 90:90 长宽比矩形裁剪图像

Question

我正在编写一个程序来裁剪图像，我的问题是我希望该矩形具有特定的纵横比 (90:90)，是否可以制作矩形而不是鼠标，使用鼠标滚轮更改其大小和点击鼠标确认？

import cv2
import numpy as np

cropping = False

x_start, y_start, x_end, y_end = 0, 0, 0, 0

image = cv2.imread('example.jpg')
oriImage = image.copy()


def mouse_crop(event, x, y, flags, param):
    # grab references to the global variables
    global x_start, y_start, x_end, y_end, cropping

    # if the left mouse button was DOWN, start RECORDING
    # (x, y) coordinates and indicate that cropping is being
    if event == cv2.EVENT_LBUTTONDOWN:
        x_start, y_start, x_end, y_end = x, y, x, y
        cropping = True

    # Mouse is Moving
    elif event == cv2.EVENT_MOUSEMOVE:
        if cropping == True:
            x_end, y_end = x, y

    # if the left mouse button was released
    elif event == cv2.EVENT_LBUTTONUP:
        # record the ending (x, y) coordinates
        x_end, y_end = x, y
        cropping = False # cropping is finished

        refPoint = [(x_start, y_start), (x_end, y_end)]

        if len(refPoint) == 2: #when two points were found
            roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
            cv2.imshow("Cropped", roi)

cv2.namedWindow("image")
cv2.setMouseCallback("image", mouse_crop)

while True:

    i = image.copy()

    if not cropping:
        cv2.imshow("image", image)

    elif cropping:
        cv2.rectangle(i, (x_start, y_start), (x_end, y_end), (255, 0, 0), 2)
        cv2.imshow("image", i)

    cv2.waitKey(1)

# close all open windows
cv2.destroyAllWindows()

Answer 1

这是您可以用来执行此操作的基本结构。在第一次单击时创建一个初始矩形，通过向上或向下滚动来调整矩形的大小，然后通过再次单击来完成裁剪。当矩形超出图像边界和“小于零”时，您需要添加一些检查来限制矩形。

# if the left mouse button was released
if event == cv2.EVENT_LBUTTONUP:
    # create rectangle
    if not cropping:
        x_start, y_start = x-20, y-20
        x_end, y_end = x+20, y+20
        cropping = True # cropping is finished
    # finish cropping
    else:
        refPoint = [(x_start, y_start), (x_end, y_end)]

        if len(refPoint) == 2: #when two points were found
            roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
            cv2.imshow("Cropped", roi)

elif event == cv2.EVENT_MOUSEWHEEL:
    print(flags)
    # scroll up
    if flags > 0:
        x_start, y_start = x_start-2, y_start-2
        x_end, y_end = x_end+2, y_end+2
    # scroll down
    else:
        x_start, y_start = x_start+2, y_start+2
        x_end, y_end = x_end-2, y_end-2

Answer 2

谢谢 :) 但我还有一个问题，我的代码现在看起来像这样：

import cv2
import numpy as np

cropping = False

x_start, y_start, x_end, y_end = 0, 0, 0, 0

image = cv2.imread('example.jpg')
oriImage = image.copy()


def mouse_crop(event, x, y, flags, param):
    # grab references to the global variables
    global x_start, y_start, x_end, y_end, cropping

    # if the left mouse button was DOWN, start RECORDING
    # (x, y) coordinates and indicate that cropping is being
    if event == cv2.EVENT_MOUSEMOVE:
        x_start, y_start, x_end, y_end = x, y, x+96, y+96
        cropping = True

    # Mouse is Moving
 #   elif event == cv2.EVENT_MOUSEMOVE:
 #       if cropping == True:
 #           x_end, y_end = x, y

    # if the left mouse button was released
    elif event == cv2.EVENT_LBUTTONUP:
        # record the ending (x, y) coordinates
#        x_end, y_end = x, y
        cropping = False # cropping is finished

        refPoint = [(x_start, y_start), (x_end, y_end)]

        if len(refPoint) == 2: #when two points were found
            roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]
            cv2.imshow("Cropped", roi)

    elif event == cv2.EVENT_MOUSEWHEEL:
        print(flags)
        # scroll up
        if flags > 0:
            x_start, y_start = x_start-15, y_start-15
            x_end, y_end = x_end+15, y_end+15
        # scroll down
        else:
            x_start, y_start = x_start+15, y_start+15
            x_end, y_end = x_end-15, y_end-15

cv2.namedWindow("image")
cv2.setMouseCallback("image", mouse_crop)

while True:

    i = image.copy()

    if not cropping:
        cv2.imshow("image", image)

    elif cropping:
        cv2.rectangle(i, (x_start, y_start), (x_end, y_end), (255, 0, 0), 2)
        cv2.imshow("image", i)

    cv2.waitKey(1)

# close all open windows
cv2.destroyAllWindows()

我的问题是：矩形跟随我的鼠标，我可以用鼠标滚轮把它变大变小，但是如果我把它变大并且鼠标移动，它又变小了