[파이썬, Python] OpenCV - 원하는 ROI 설정 후 투시변환하기

💡 문제.

namecard.jpg에 retangle과 circle을 그리고 마우스이벤트를 줘서 칸에 맞추면 투시변환을 해보자.

 

 

import cv2
import numpy as np
import sys

def drawROI(img, corners):
    cpy = img.copy()
    c1 = (192, 192, 255)
    c2 = (128, 128, 255)

    for pt in corners:
        cv2.circle(cpy, tuple(pt.astype(int)), 25, c1, -1, cv2.LINE_AA)

    cv2.line(cpy, tuple(corners[0].astype(int)), tuple(corners[1].astype(int)), c2, 2, cv2.LINE_AA)
    cv2.line(cpy, tuple(corners[1].astype(int)), tuple(corners[2].astype(int)), c2, 2, cv2.LINE_AA)
    cv2.line(cpy, tuple(corners[2].astype(int)), tuple(corners[3].astype(int)), c2, 2, cv2.LINE_AA)
    cv2.line(cpy, tuple(corners[3].astype(int)), tuple(corners[0].astype(int)), c2, 2, cv2.LINE_AA)

    return cpy


def onMouse(event, x, y, flags, param):
    global srcQuad, dragSrc, ptOld, src

    if event == cv2.EVENT_LBUTTONDOWN:
        for i in range(4):
            if cv2.norm(srcQuad[i] - (x, y)) < 25:
                dragSrc[i] = True
                ptOld = (x, y)
                break

    if event == cv2.EVENT_LBUTTONUP:
        for i in range(4):
            dragSrc[i] = False

    if event == cv2.EVENT_MOUSEMOVE:
        for i in range(4):
            if dragSrc[i]:
                dx = x - ptOld[0]
                dy = y - ptOld[1]
                srcQuad[i] += (dx, dy)
                cpy = drawROI(src, srcQuad)
                cv2.imshow('img', cpy)
                ptOld = (x, y)
                break

src = cv2.imread('namecard.jpg')

h, w = src.shape[:2]
dh = 500
# A4용지 크기: 210*297cm
dw = round(dh * 297 / 210)

srcQuad = np.array([[30, 30], [30, h-30], [w-30, h-30], [w-30, 30]], np.float32)
dstQuad = np.array([[0, 0], [0, dh], [dw, dh], [dw, 0]], np.float32)

dragSrc = [False, False, False, False]

disp = drawROI(src, srcQuad)
cv2.imshow('img', disp)
cv2.setMouseCallback('img', onMouse)

while True:
    key = cv2.waitKey()
    if key == 13:
        break
    elif key == 27:
        sys.exit()

pers = cv2.getPerspectiveTransform(srcQuad, dstQuad)
dst = cv2.warpPerspective(src, pers, (dw, dh), flags=cv2.INTER_CUBIC)

cv2.imshow('dst', dst)
cv2.waitKey()