在OpenCV中放大后，Python会捕捉图像的特定部分 [英] Python capture a specific part of an image after zooming in OpenCV
本文介绍了在OpenCV中放大后，Python会捕捉图像的特定部分的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
所以我尝试使用我的网络摄像头进行放大和缩小，并在缩放后捕捉实时网络摄像头中特定部分的图像。但是，我可以放大和缩小，但通过使用"；cam.read()"；，我只能捕获整个图像，而不能捕获我已缩放的图像的特定部分。我已经定义了ROI，但现在的问题是ROI正在工作，但我无法使图像放大或缩小。我似乎找不到问题所在。
import cv2
import time
import os
import datetime
from threading import Thread
from queue import Queue
import numpy as np
import imutils
from PIL import Image
class Camera:
def __init__(self, mirror=False):
self.data = None
self.cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)
self.WIDTH = 640
self.HEIGHT = 480
self.center_x = self.WIDTH / 2
self.center_y = self.HEIGHT / 2
self.touched_zoom = False
self.image_queue = Queue()
self.video_queue = Queue()
self.scale = 1
self.__setup()
self.recording = False
self.image_coordinates = []
self.extract = False
self.selected_ROI = False
self.select_roi()
self.mirror = mirror
def __setup(self):
self.cam.set(cv2.CAP_PROP_FRAME_WIDTH, self.WIDTH)
self.cam.set(cv2.CAP_PROP_FRAME_HEIGHT, self.HEIGHT)
time.sleep(2)
def get_location(self, x, y):
self.center_x = x
self.center_y = y
self.touched_zoom = True
def stream(self):
def streaming():
self.ret = True
while self.ret:
self.ret, np_image = self.cam.read()
if np_image is None:
continue
if self.mirror:
np_image = cv2.flip(np_image, 1)
if self.touched_zoom:
np_image = self.__zoom(np_image, (self.center_x, self.center_y))
else:
if not self.scale == 1:
np_image = self.__zoom(np_image)
self.data = np_image
k = cv2.waitKey(1)
if k == ord('q'):
self.release()
break
Thread(target=streaming).start()
def __zoom(self, img, center=None):
height, width = img.shape[:2]
if center is None:
center_x = int(width / 2)
center_y = int(height / 2)
radius_x, radius_y = int(width / 2), int(height / 2)
else:
rate = height / width
center_x, center_y = center
if center_x < width * (1-rate):
center_x = width * (1-rate)
elif center_x > width * rate:
center_x = width * rate
if center_y < height * (1-rate):
center_y = height * (1-rate)
elif center_y > height * rate:
center_y = height * rate
center_x, center_y = int(center_x), int(center_y)
left_x, right_x = center_x, int(width - center_x)
up_y, down_y = int(height - center_y), center_y
radius_x = min(left_x, right_x)
radius_y = min(up_y, down_y)
radius_x, radius_y = int(self.scale * radius_x), int(self.scale * radius_y)
min_x, max_x = center_x - radius_x, center_x + radius_x
min_y, max_y = center_y - radius_y, center_y + radius_y
cropped = img[min_y:max_y, min_x:max_x]
new_cropped = cv2.resize(cropped, (width, height), interpolation=cv2.INTER_CUBIC)
return new_cropped
def touch_init(self):
self.center_x = self.WIDTH / 2
self.center_y = self.HEIGHT / 2
self.touched_zoom = False
self.scale = 1
def zoom_out(self):
if self.scale < 1:
self.scale += 0.1
if self.scale == 1:
self.center_x = self.WIDTH
self.center_y = self.HEIGHT
self.touched_zoom = False
def zoom_in(self):
if self.scale > 0.2:
self.scale -= 0.1
def zoom(self, num):
if num == 0:
self.zoom_in()
elif num == 1:
self.zoom_out()
elif num == 2:
self.touch_init()
def save_picture(self):
ret, img = self.cam.read()
if ret:
now1 = datetime.datetime.now()
now_str1 = now1.strftime("%Y-%m-%d-%H-%M-%S")
outfilename1 = 'Img-{}.jpg'.format(now_str1)
path = 'C:/Users/dashi/Documents/MyRiV/espeyh_images'
cv2.imwrite(os.path.join(path, outfilename1), img)
path1 = ('C:/Users/dashi/Documents/MyRiV/espeyh_images/' + outfilename1)
imag = cv2.imread(path1)
lower = np.array([140, 140, 140])
upper = np.array([255, 255, 255])
thresh = cv2.inRange(imag, lower, upper)
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (26, 30))
morph = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, kernel)
mask = 255 - morph
result = cv2.bitwise_and(imag, imag, mask=mask)
cv2.imshow('Background Removed', result)
outfilename2 = 'Img-{}.jpg'.format(now_str1)
path2 = ('C:/Users/dashi/Documents/MyRiV/modified_images')
cv2.imwrite(os.path.join(path2, outfilename2), result)
def record_video(self):
fc = 20.0
record_start_time = time.time()
now = datetime.datetime.now()
date = now.strftime('%Y%m%d')
t = now.strftime('%H')
num = 1
filename = 'C:/Users/dashi/Documents/MyRiV/espeyh_videos/captured_{}_{}.avi'.format(date, t, num)
while os.path.exists(filename):
num += 1
filename = 'videos/captured_{}_{}_{}.avi'.format(date, t, num)
codec = cv2.VideoWriter_fourcc('D', 'I', 'V', 'X')
out = cv2.VideoWriter(filename, codec, fc, (int(self.cam.get(3)), int(self.cam.get(4))))
while self.recording:
if time.time() - record_start_time >= 600:
self.record_video()
break
ret, frame = self.cam.read()
if ret:
if len(os.listdir('C:/Users/dashi/Documents/MyRiV/espeyh_videos')) >= 100:
name = self.video_queue.get()
if os.path.exists(name):
os.remove(name)
out.write(frame)
self.video_queue.put_nowait(filename)
k = cv2.waitKey(1)
if k == ord('q'):
break
def crop_ROI(self):
if self.selected_ROI:
self.cropped_image = self.frame.copy()
x1 = self.image_coordinates[0][0]
y1 = self.image_coordinates[0][1]
x2 = self.image_coordinates[1][0]
y2 = self.image_coordinates[1][1]
self.cropped_image = self.cropped_image[y1:y2, x1:x2]
print('Cropped image: {} {}'.format(self.image_coordinates[0], self.image_coordinates[1]))
else:
print('Select ROI to crop before cropping')
def show_cropped_ROI(self):
cv2.imshow('cropped image', self.cropped_image)
def select_roi(self):
while True:
if self.cam.isOpened():
# Read frame
(self.status, self.frame) = self.cam.read()
cv2.imshow('image', self.frame)
key = cv2.waitKey(2)
# Crop image
if key == ord('c'):
self.clone = self.frame.copy()
cv2.namedWindow('image')
cv2.setMouseCallback('image', self.mouse_callback)
while True:
key = cv2.waitKey(2)
cv2.imshow('image', self.clone)
# Crop and display cropped image
if key == ord('c'):
self.crop_ROI()
self.show_cropped_ROI()
# Resume video
if key == ord('r'):
break
# Close program with keyboard 'q'
if key == ord('q'):
cv2.destroyAllWindows()
exit(1)
else:
pass
def show(self):
while True:
frame = self.data
if frame is not None:
cv2.imshow('Zooming', frame)
cv2.setMouseCallback('Zooming', self.mouse_callback)
key = cv2.waitKey(1)
if key == ord('f'):
if key == ord('q'):
self.release()
cv2.destroyAllWindows()
break
elif key == ord('z'):
self.zoom_in()
elif key == ord('x'):
self.zoom_out()
elif key == ord('p'):
self.save_picture()
elif key == ord('v'):
self.touch_init()
elif key == ord('r'):
self.recording = not self.recording
if self.recording:
t = Thread(target=cam.record_video)
t.start()
elif key == ord('k'):
self.select_roi()
def release(self):
self.cam.release()
cv2.destroyAllWindows()
def mouse_callback(self, event, x, y, flag, parameters):
if event == cv2.EVENT_LBUTTONDBLCLK:
self.get_location(x, y)
self.zoom_in()
elif event == cv2.EVENT_RBUTTONDOWN:
self.zoom_out()
elif event == cv2.EVENT_LBUTTONDOWN:
self.image_coordinates = [(x,y)]
self.extract = True
elif event == cv2.EVENT_LBUTTONUP:
self.image_coordinates.append((x,y))
self.extract = False
self.selected_ROI = True
# Draw rectangle around ROI
cv2.rectangle(self.clone, self.image_coordinates[0], self.image_coordinates[1], (0,255,0), 2)
elif event == cv2.EVENT_RBUTTONDOWN:
self.clone = self.frame.copy()
self.selected_ROI = False
if __name__ == '__main__':
cam = Camera(mirror=True)
cam.stream()
cam.show()
推荐答案
您应该像裁剪显示器一样裁剪正在录制的图像。
此外，您正在从2个线程读取视频捕获。我认为这不是一个好主意：您可能正在显示和录制一个超过2的图像。(第一个图像显示，第二个图像录制，第三个图像显示，...)。您应该只在一个位置调用self.cam.read()，根据需要裁剪图像，并使其既可用于显示又可用于录制。
这篇关于在OpenCV中放大后，Python会捕捉图像的特定部分的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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