使用opencv python通过鼠标拖动来调整图像大小

Question

I am new to python and computer vision programming. though I am trying to make an image resizing tool. for this purpose I am using python3.x and opencv2. so far now I am able to resize an image by following code, its just an example.

my_img = cv2.imread('4.1.04.tiff')
resized_img = cv2.resize(my_img,None,fx=0.5, fy=0.5, interpolation = 
cv2.INTER_CUBIC)
cv2.imshow('Image',resized_img)
cv2.waitKey(0)
cv2.destroyAllWindows()

Well, my problem is I dont know how to do resize an image by dragging mouse. please let me know if it is possible in opencv or not and can be done using other libraries in python. Thanks!

Answer 1

I partially done the code for resizing image but its not working perfectly, there is some main window size problem occurring. If you re-run the code you will get it. I can not see full window and tracker bar too

import cv2
#import numpy as np

pro_img = None
a1 = 0.5 #for default size of image

def nothing(x):
    pass

def BnC_control(alpha):
    alpha = alpha/10
    #print(type(alpha))
    if alpha >= 0.1:
        return alpha
    else: 
        return 0.1


img = cv2.imread('watch.jpg')
#img = np.zeros((512,512,3),np.uint16)
cv2.namedWindow('Window1',cv2.WINDOW_AUTOSIZE)
cv2.createTrackbar('Alpha','Window1',1,10,nothing)



while(True):
    #r = BnC_control(a)
    #pro_img = cv2.resize(img,None,fx=0.3,fy=0.3)
    a = cv2.getTrackbarPos('Alpha','Window1')
    a1 = BnC_control(a)
    #print(a1)
    re_img = cv2.resize(img,None,fx=a1,fy=a1,interpolation = cv2.INTER_CUBIC)
    cv2.imshow('Window1',re_img)
    k = cv2.waitKey(1) & 0xFF
    if k == 27:
        break

cv2.destroyAllWindows()

Also when I change interpolation to INTER_AREA then it goes wrong..nothing happens and trackerbar gets disappear.

Answer 2

A simple code to show a trackbar used to resize the image. For more detail, see this link .

import cv2
import numpy as np

# method to be called by trackbar event
def onChange(pos):
    global img,dst,rows,cols

    # get value from trackbar
    value = cv2.getTrackbarPos("resize_trackbar", "Result")

    # resize image
    dst = cv2.resize(src=img, dsize=(cols+value,rows+value))

#Run Main
if __name__ == "__main__" :

    img = cv2.imread("image.jpg", -1)

    # get original image size
    rows,cols = img.shape[:2]

    # initialize dst image
    dst = np.copy(img)

    # create display window
    cv2.namedWindow("Result", cv2.WINDOW_NORMAL)

    # create trackbar
    cv2.createTrackbar("resize_trackbar", "Result", 0, 50, onChange)

    while True:
        cv2.imshow("Result", dst)
        key = cv2.waitKey(1)
        if key == ord('q'):
            break

    cv2.destroyAllWindows()