openCv crop image

Question

I running into problems with my openCv IplImage cropping. Assuming both tmp and img are IplImage* . Using the code:

printf(\"Orig dimensions: %dx%d\\n\", im         


        

Answer 1

you can easily crop the image in python by using

roi = oriImage[refPoint[0][1]:refPoint[1][1], refPoint[0][0]:refPoint[1][0]]

In order to get the two points you can call cv2.setMouseCallback("image", mouse_crop). The function is something like this

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.imwrite("crop.jpg",roi)

You can get details from here : Mouse Click and Cropping using Python

For C++ you can do like below:

void mouse_call(int event,int x,int y,int,void*)
{
    if(event==EVENT_LBUTTONDOWN)
    {
        leftDown=true;
        cor1.x=x;
        cor1.y=y;
        cout <<"Corner 1: "<20&&abs(y-cor1.y)>20) //checking whether the region is too small
        {
            leftup=true;
            cor2.x=x;
            cor2.y=y;
            cout<<"Corner 2: "<

You can get details from here : Mouse Click and Cropping using C++