opencv计算机视觉学习笔记一

第二章 处理文件 摄像头和图形用户界面

1 基本i/o脚本

读写图像文件

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 12:22
# @Author : Retacn
# @Site : 读/写图像文件
# @File : imageReadWrite.py
# @Software: PyCharm

import cv2
import numpy as np
from matplotlib import pyplot as plt

#色正方形图像
img=np.zeros((3,3),dtype=np.uint8)
print(img)
#输出内容如下:
#[[0 0 0]
# [0 0 0]
# [0 0 0]]
#查看图像结构
print(img.shape)
#输出结果
# (3, 3)

#将图像转化成BGR
img2=cv2.cvtColor(img,cv2.COLOR_BAYER_BG2BGR)
print(img2)
#输出内容如下:
#[[[0 0 0]
# [0 0 0]
# [0 0 0]]
#
# [[0 0 0]
# [0 0 0]
# [0 0 0]]
#
# [[0 0 0]
# [0 0 0]
# [0 0 0]]]
#查看图像结构
print(img2.shape)
#输出结果为:
#(3, 3, 3)

#将png格式图像转换为jpeg格式
image=cv2.imread('../j.png')
cv2.imwrite('../j.jpg',image)
#imread参数
# IMREAD_ANYCOLOR = 4
# IMREAD_ANYDEPTH = 2
# IMREAD_COLOR = 1
# IMREAD_GRAYSCALE = 0 灰度图像
# IMREAD_LOAD_GDAL = 8
# IMREAD_UNCHANGED = -1


#显示图像
plt.subplot(221),plt.imshow(img)
plt.title("img"),plt.xticks([]),plt.yticks([])

plt.subplot(222),plt.imshow(img2)
plt.title("img2"),plt.xticks([]),plt.yticks([])

plt.subplot(223),plt.imshow(image)
plt.title("image"),plt.xticks([]),plt.yticks([])


plt.show()

图像与原始字节之间的转换

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 12:48
# @Author : Retacn
# @Site : 图像与原始字节之间的转换
# @File : image2array.py
# @Software: PyCharm
import cv2
import numpy as np
import os
from matplotlib import pyplot as plt

#读入图像
img=cv2.imread('../test.jpg',cv2.IMREAD_GRAYSCALE)
print(img)
#显示转换为标准一维python bytearray
byteArray=bytearray(img)

img=cv2.imread('../test1.jpg')
byteArray1=bytearray(img)


#将字节转换为图像
grayImage=np.array(byteArray).reshape(220,265)
bgrImage=np.array(byteArray1).reshape(800,480,3)

#将随机字节转换为灰度图像和BGR图像

#创建随机字节
randomByteArray=bytearray(os.urandom(120000))
flatNumpyArray=np.array(randomByteArray)

#将字节转换为400*300 的灰度图像
ran_grayImage=flatNumpyArray.reshape(300,400)

#将字节转换为400*100的BGR图像
ran_bgrImage=flatNumpyArray.reshape(100,400,3)



#显示图像
plt.subplot(221),plt.imshow(grayImage)
plt.title("grayImage"),plt.xticks([]),plt.yticks([])

plt.subplot(222),plt.imshow(bgrImage)
plt.title("bgrImage"),plt.xticks([]),plt.yticks([])

plt.subplot(223),plt.imshow(ran_grayImage)
plt.title("ran_grayImage"),plt.xticks([]),plt.yticks([])

plt.subplot(224),plt.imshow(ran_bgrImage)
plt.title("ran_bgrImage"),plt.xticks([]),plt.yticks([])

plt.show()

Array访问图形数据

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 13:17
# @Author : Retacn
# @Site : array访问图像数据
# @File : arrayAccessImage.py
# @Software: PyCharm

import cv2
import numpy as np
from matplotlib import pyplot as plt

# 读入图像
img = cv2.imread('../test.jpg')
print(img[0, 0])
# 修改图像数据
img[0, 0] = [255, 251, 251]
print(img[0, 0])

# 修改指定坐标的颜色值
print(img.item(150, 120, 0))

img.itemset((150,120,0),255)
print(img.item(150, 120, 0))

#图像完全没有绿色
img[:,:,1]=0

#将图像的一部份复制到图像的另一个位置
img_j = cv2.imread('../test1.jpg')
my_roi=img_j[0:100,0:100]
img_j[200:300,200:300]=my_roi

#取得图像属性
print(img.shape)#宽度/高度/通道数
print(img.size)#图像像素的大小
print(img.dtype)#图像的数据类型

# 显示图像
plt.subplot(121), plt.imshow(img)
plt.title('change'), plt.xticks([]), plt.yticks([])

plt.subplot(122), plt.imshow(img_j)
plt.title('img_j'), plt.xticks([]), plt.yticks([])

plt.show()

视频文件的读写

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 13:57
# @Author : Retacn
# @Site : 视频文件的读写
# @File : videoRead.py
# @Software: PyCharm

import cv2

cameraCapture = cv2.VideoCapture('../test.avi')
FPS = 30
size = (int(cameraCapture.get(cv2.CAP_PROP_FRAME_WIDTH))
 , int(cameraCapture.get(cv2.CAP_PROP_FRAME_HEIGHT)))
videoWrite = cv2.VideoWriter('../testOut.avi', cv2.VideoWriter_fourcc('I', '4', '2', '0'), FPS, size)

success, frame = cameraCapture.read()
while success:
 videoWrite.write(frame)
 success, frame = cameraCapture.read()
cameraCapture.release()

捕获摄像头的帧

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 13:39
# @Author : Retacn
# @Site : 捕获摄像头的帧
# @File : videoReadWrite.py
# @Software: PyCharm

import cv2

#
cameraCapture=cv2.VideoCapture(0)
FPS=30
size=(int(cameraCapture.get(cv2.CAP_PROP_FRAME_WIDTH))
 ,int(cameraCapture.get(cv2.CAP_PROP_FRAME_HEIGHT)))
videoWrite=cv2.VideoWriter('../test.avi',cv2.VideoWriter_fourcc('I','4','2','0'),FPS,size)

success,frame=cameraCapture.read()
numFramesRemaining=10*FPS-1
while success and numFramesRemaining>0:
 videoWrite.write(frame)
 success,frame=cameraCapture.read()
 numFramesRemaining-=1
cameraCapture.release()

当需要同步一组摄像头或是一个多头摄像头

success0=cameraCapture0.grab()
success1=cameraCapture1.grab()
if success0 and success1:
 frame0=cameraCapture0.retrieve()
 frame1=cameraCapture1.retrieve()

在窗口显示图像

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 14:09
# @Author : Retacn
# @Site : 在窗口显示图像
# @File : imageShow.py
# @Software: PyCharm
import cv2
import numpy as np

img=cv2.imread('../test.jpg')
cv2.imshow('Image',img)
cv2.waitKey()
cv2.destroyAllWindows()

在窗口显示摄像头帧

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/27 14:13
# @Author : Retacn
# @Site : 在窗口显示摄像头帧
# @File : videoCamera.py
# @Software: PyCharm

import cv2
import numpy as np

clicked=False
def onMouse(event,x,y,flags,param):
 global clicked
 if event==cv2.EVENT_LBUTTONUP:#左健抬起
 clicked=True

cameraCapture=cv2.VideoCapture(0)
cv2.namedWindow("VideoWindow")
cv2.setMouseCallback('VideoWindow',onMouse)

print('Showing camera feed,Click window or press any key to stop.')
success,frame=cameraCapture.read()
while success and cv2.waitKey(1)==-1 and not clicked:
 cv2.imshow('VideoWindow',frame)
 success,frame=cameraCapture.read()

cv2.destroyWindow('VideoWindow')
cameraCapture.release()

2 cameo项目

3 cameo面向对象的设计

Managers.py文件

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/28 13:30
# @Author : Retacn
# @Site : 面向对象的设计
# @File : cameo.py
# @Software: PyCharm

import cv2
import numpy as np
import time


'''
 视频管理
'''
class CaptureManager(object):
 def __init__(self,
 capture, #摄像头通道
 previewWindowManager=None,#窗口管理器
 shouldMirrorPreview=False):#摄像头预览的镜像选项

 self.previewWindowManager=previewWindowManager
 self.shouldMirrorPreview=shouldMirrorPreview

 #定义非公有变量,单下划线开始,为保护变量,只有类对象或子类对象可以访问 protected
 #如果以双下划线开始,为私有成员变量,只有类对象自已可以访问,像private
 self._capture=capture
 self._channel=0
 self._enteredFrame=False
 self._frame=None
 self._imageFilename=None
 self._videoFilename=None
 self._videoEncoding=None
 self._videoWriter=None

 self.startTime=None
 self._framesElapsed=int(0)
 self._fpsEstimate=None

 @property
 def channel(self):
 return self._channel

 @channel.setter
 def channel(self,value):
 if self._channel!=value:
 self._channel=value
 self._frame=None

 @property
 def frame(self):
 if self._enteredFrame and self._frame is None:
 _,self._frame=self._capture.retrieve()
 return self._frame

 @property
 def isWritingImage(self):
 return self._imageFilename is not None

 @property
 def isWritingVideo(self):
 return self._videoFilename is not None


 #只能同步一帧
 def enterFrame(self):

 assert not self._enteredFrame, \
 'previous enterFrame() had no matching exitFrame()'

 if self._capture is not None:
 self._enteredFrame=self._capture.grab()

 #可以从当前通道中取得图像,估计帧率,显示图像,执行暂停的请求,向文件中写入图像
 def exitFrame(self):
 if self.frame is None:
 self._enteredFrame=False
 return

 #计算帧率
 if self._framesElapsed==0:
 self._startTime=time.time()
 else:
 timeElapsed=time.time()-self._startTime
 self._fpsEstimate=self._framesElapsed/timeElapsed

 self._framesElapsed+=1

 #通过窗体显示图像
 if self.previewWindowManager is not None:
 if self.shouldMirrorPreview:
 mirroredFrame=np.fliplr(self._frame).copy()
 self.previewWindowManager.show(mirroredFrame)
 else:
 self.previewWindowManager.show(self._frame)

 #保存图像文件
 if self.isWritingImage:
 cv2.imwrite(self._imageFilename,self._frame)
 self._imageFilename=None

 #保存视频文件
 self._writeVideoFrame()

 #释放资源
 self._frame=None
 self._enteredFrame=False

 #保存图片,公有函数
 def writeImage(self,filename):
 self._imageFilename=filename

 #开始保存视频,公有函数
 def startWritingVideo(self,filename,encoding=cv2.VideoWriter_fourcc('I','4','2','0')):
 self._videoFilename=filename
 self._videoEncoding=encoding

 #停止视频写入,公有函数
 def stopWritingVideo(self):
 self._videoFilename=None
 self._videoEncoding=None
 self._videoWriter=None

 #写入视频帧
 def _writeVideoFrame(self):
 if not self.isWritingVideo:
 return

 if self._videoWriter is None:
 fps=self._capture.get(cv2.CAP_PROP_FPS)
 if fps==0.0:
 if self._framesElapsed<20:
 return
 else:
 fps=self._fpsEstimate
 size=(int(self._capture.get(cv2.CAP_PROP_FRAME_WIDTH)),
 int(self._capture.get(cv2.CAP_PROP_FRAME_HEIGHT)))

 self._videoWriter=cv2.VideoWriter(self._videoFilename,
 self._videoEncoding,
 fps,
 size)
 self._videoWriter.write(self._frame)

'''
 窗口管理,支持键盘事件
'''
class WindowManager(object):

 def __init__(self,
 windowName,#窗体名称
 keypressCallback=None):#按键回调函数
 self.keypressCallback=keypressCallback

 self._windowName=windowName
 self._isWindowCreate=False

 #检查窗体是否被创建
 @property
 def isWindowCreated(self):
 return self._isWindowCreate

 #创建窗体
 def createWindow(self):
 cv2.namedWindow(self._windowName)
 self._isWindowCreate=True

 #显示图像
 def show(self,frame):
 cv2.imshow(self._windowName,frame)

 #关闭窗体释放资源
 def destroyWindow(self):
 cv2.destroyWindow(self._windowName)
 self._isWindowCreate=False

 #处理键盘事件
 def processEvents(self):
 keycode=cv2.waitKey(1)
 if self.keypressCallback is not None and keycode!=-1:
 keycode&=0xFF #ESC 退出
 self.keypressCallback(keycode)


cameo.py文件

示例代码如下:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2016/11/28 14:45
# @Author : Retacn
# @Site : cameo实现,有两种启动方法: run() 和 onkeypress()
# @File : cameo.py.py
# @Software: PyCharm

import cv2
from Two.cameo.managers import WindowManager,CaptureManager

class Cameo(object):

 def __init__(self):
 self._windowManager=WindowManager('Cameo',self.onkeypress)

 self._captureManager=CaptureManager(cv2.VideoCapture(0),self._windowManager,True)

 def run(self):
 self._windowManager.createWindow()
 while self._windowManager.isWindowCreated:
 self._captureManager.enterFrame()
 frame=self._captureManager.frame

 self._captureManager.exitFrame()
 self._windowManager.processEvents()

 def onkeypress(self,keycode):
 '''
 space-> 载图
 tab->启动和停止视频录制
 esc->退出应用

 :param keycode:
 :return:
 '''
 if keycode==32:#space
 self._captureManager.writeImage('screenshot.png')
 elif keycode==9:#tab
 if not self._captureManager.isWritingVideo:
 self._captureManager.startWritingVideo('screencast.avi')
 else:
 self._captureManager.stopWritingVideo()
 elif keycode==27:#esc
 self._windowManager.destroyWindow()
if __name__=='__main__':
 Cameo().run()