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opencv--GrabCut

news 来源：原创 2024/5/21 11:35:48

GrabCut

-通过交互式的方式获得前景物体

GrabCut原理

用户指定前景的大体区域，剩下的为背景区域
用户还可以明确指定某些地方为前景或背景、
GrabCut采用分段迭代的方式分析前景物体形成模型树
最后根据权重决定某个像素是前景还是背景

实战GrabCut

主体结构
鼠标事件的处理
调用GrabCut实现前景与背景的分离

鼠标事件处理程序编写

import cv2 as cv
import numpy as np


class App:
    startX = 0
    startY = 0
    flag_rect = False
    def onmouse(self,event,x,y,flags,param):
        print('onmouse')
        if event == cv.EVENT_LBUTTONDOWN:
            self.startX = x
            self.startY = y
            self.flag_rect = True
            print("EVENT_LBUTTONDOWN")
        elif event == cv.EVENT_LBUTTONUP:
            self.flag_rect = False
            cv.rectangle(self.img, (self.startX, self.startY), (x, y), (0, 0, 255), 3)
            print('EVENT_LBUTTONUP')
        elif event == cv.EVENT_MOUSEMOVE:
            if self.flag_rect == True:
                self.img = self.img2.copy()
                cv.rectangle(self.img, (self.startX, self.startY), (x, y), (255, 0, 0), 3)
                print('EVENT_MOUSEMOVE')


    def run(self):
        cv.namedWindow('input')
        cv.setMouseCallback('input', self.onmouse)
        self.img = cv.imread('dog.jpeg')
        self.img2 = self.img.copy()
        while True:
            cv.imshow("input", self.img)
            k = cv.waitKey(100)
            if k == 27:
                break

if __name__ == '__main__':

    A = App()
    A.run()

GrabCut API

grabCut(img, mask, rect, bgdModel, fgdModel, 5, mode)
mask 生成的掩码
- BGD: 背景，0
- FGD：前景，1
- PR_BGD：可能是背景，2
- PR_FGD：可能是背景，3
Model
- bgdModel,np.float64 type zero array of size (1,65).
- fgdModel,同上
mode
- GC_INT_WITH_RECT
- GC_INT_WITH_MASK

import cv2 as cv
import numpy as np


class App:
    startX = 0
    startY = 0
    flag_rect = False
    rect = (0, 0, 0, 0)
    def onmouse(self,event,x,y,flags,param):
        print('onmouse')
        if event == cv.EVENT_LBUTTONDOWN:
            self.startX = x
            self.startY = y
            self.flag_rect = True
            print("EVENT_LBUTTONDOWN")
        elif event == cv.EVENT_LBUTTONUP:
            self.flag_rect = False
            cv.rectangle(self.img, (self.startX, self.startY), (x, y), (0, 0, 255), 3)
            self.rect = (min(self.startX, x), min(self.startY, y), self.startX-x, self.startY-y)
            print('EVENT_LBUTTONUP')
        elif event == cv.EVENT_MOUSEMOVE:
            if self.flag_rect == True:
                self.img = self.img2.copy()
                cv.rectangle(self.img, (self.startX, self.startY), (x, y), (255, 0, 0), 3)
                print('EVENT_MOUSEMOVE')


    def run(self):
        cv.namedWindow('input')
        cv.setMouseCallback('input', self.onmouse)
        self.img = cv.imread('luban1.png')
        self.img2 = self.img.copy()
        self.mask = np.zeros(self.img.shape[:2], dtype=np.uint8)
        self.output = np.zeros(self.img.shape, np.uint8)

        while True:
            cv.imshow("input", self.img)
            cv.imshow('output', self.output)
            k = cv.waitKey(100)
            if k == 27:
                break
            elif k == ord('g'):
                bgdModel = np.zeros((1, 65), np.float64)
                fgdModel = np.zeros((1, 65), np.float64)
                cv.grabCut(self.img2, self.mask, self.rect, bgdModel, fgdModel, 1, mode=cv.GC_INIT_WITH_RECT)
            mask2 = np.where((self.mask == 1)|(self.mask == 3), 255, 0).astype("uint8")
            self.output = cv.bitwise_and(self.img2, self.img2, mask=mask2)



if __name__ == '__main__':

    A = App()
    A.run()