opencv計算機視覺學習筆記一

轉載來自https://blog.csdn.net/retacn_yue/article/details/53608358
第二章 處理文件 攝像頭和圖形用戶界面

1 基本i/o腳本

讀寫圖像文件

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 12:22

@Author : Retacn

@Site : 讀/寫圖像文件

@File : imageReadWrite.py

@Software: PyCharm

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

色正方形圖像

img=np.zeros((3,3),dtype=np.uint8)
print(img)

輸出內容如下:

[[0 0 0]

[0 0 0]

[0 0 0]]

查看圖像結構

print(img.shape)

輸出結果

(3, 3)

將圖像轉化成BGR

img2=cv2.cvtColor(img,cv2.COLOR_BAYER_BG2BGR)
print(img2)

輸出內容如下:

[[[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]]]

查看圖像結構

print(img2.shape)

輸出結果爲:

(3, 3, 3)

將png格式圖像轉換爲jpeg格式

image=cv2.imread(‘../j.png’)
cv2.imwrite(‘../j.jpg’,image)

imread參數

IMREAD_ANYCOLOR = 4

IMREAD_ANYDEPTH = 2

IMREAD_COLOR = 1

IMREAD_GRAYSCALE = 0 灰度圖像

IMREAD_LOAD_GDAL = 8

IMREAD_UNCHANGED = -1

顯示圖像

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()

圖像與原始字節之間的轉換

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 12:48

@Author : Retacn

@Site : 圖像與原始字節之間的轉換

@File : image2array.py

@Software: PyCharm

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

讀入圖像

img=cv2.imread(‘../test.jpg’,cv2.IMREAD_GRAYSCALE)
print(img)

顯示轉換爲標準一維python bytearray

byteArray=bytearray(img)

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

將字節轉換爲圖像

grayImage=np.array(byteArray).reshape(220,265)
bgrImage=np.array(byteArray1).reshape(800,480,3)

將隨機字節轉換爲灰度圖像和BGR圖像

創建隨機字節

randomByteArray=bytearray(os.urandom(120000))
flatNumpyArray=np.array(randomByteArray)

將字節轉換爲400*300 的灰度圖像

ran_grayImage=flatNumpyArray.reshape(300,400)

將字節轉換爲400*100的BGR圖像

ran_bgrImage=flatNumpyArray.reshape(100,400,3)

顯示圖像

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訪問圖形數據

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 13:17

@Author : Retacn

@Site : array訪問圖像數據

@File : arrayAccessImage.py

@Software: PyCharm

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

讀入圖像

img = cv2.imread(‘../test.jpg’)
print(img[0, 0])

修改圖像數據

img[0, 0] = [255, 251, 251]
print(img[0, 0])

修改指定座標的顏色值

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

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

圖像完全沒有綠色

img[:,:,1]=0

將圖像的一部份複製到圖像的另一個位置

img_j = cv2.imread(‘../test1.jpg’)
my_roi=img_j[0:100,0:100]
img_j[200:300,200:300]=my_roi

取得圖像屬性

print(img.shape)#寬度/高度/通道數
print(img.size)#圖像像素的大小
print(img.dtype)#圖像的數據類型

顯示圖像

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()

視頻文件的讀寫

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 13:57

@Author : Retacn

@Site : 視頻文件的讀寫

@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()

捕獲攝像頭的幀

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 13:39

@Author : Retacn

@Site : 捕獲攝像頭的幀

@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()

當需要同步一組攝像頭或是一個多頭攝像頭

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

在窗口顯示圖像

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 14:09

@Author : Retacn

@Site : 在窗口顯示圖像

@File : imageShow.py

@Software: PyCharm

import cv2
import numpy as np

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

在窗口顯示攝像頭幀

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/27 14:13

@Author : Retacn

@Site : 在窗口顯示攝像頭幀

@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:#左健擡起
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項目

3 cameo面向對象的設計

Managers.py文件

示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/28 13:30

@Author : Retacn

@Site : 面向對象的設計

@File : cameo.py

@Software: PyCharm

import cv2
import numpy as np
import time

”’
視頻管理
”’
class CaptureManager(object):
def init(self,
capture, #攝像頭通道
previewWindowManager=None,#窗口管理器
shouldMirrorPreview=False):#攝像頭預覽的鏡像選項

    self.previewWindowManager=previewWindowManager
    self.shouldMirrorPreview=shouldMirrorPreview

    #定義非公有變量,單下劃線開始,爲保護變量,只有類對象或子類對象可以訪問 protected
    #如果以雙下劃線開始,爲私有成員變量,只有類對象自已可以訪問,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


#只能同步一幀
def enterFrame(self):

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

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

#可以從當前通道中取得圖像,估計幀率,顯示圖像,執行暫停的請求,向文件中寫入圖像
def exitFrame(self):
    if self.frame is None:
        self._enteredFrame=False
        return

    #計算幀率
    if self._framesElapsed==0:
        self._startTime=time.time()
    else:
        timeElapsed=time.time()-self._startTime
        self._fpsEstimate=self._framesElapsed/timeElapsed

    self._framesElapsed+=1

    #通過窗體顯示圖像
    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)

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

    #保存視頻文件
    self._writeVideoFrame()

    #釋放資源
    self._frame=None
    self._enteredFrame=False

#保存圖片,公有函數
def writeImage(self,filename):
    self._imageFilename=filename

#開始保存視頻,公有函數
def startWritingVideo(self,filename,encoding=cv2.VideoWriter_fourcc('I','4','2','0')):
    self._videoFilename=filename
    self._videoEncoding=encoding

#停止視頻寫入,公有函數
def stopWritingVideo(self):
    self._videoFilename=None
    self._videoEncoding=None
    self._videoWriter=None

#寫入視頻幀
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,支持鍵盤事件
”’
class WindowManager(object):

def __init__(self,
             windowName,#窗體名稱
             keypressCallback=None):#按鍵回調函數
    self.keypressCallback=keypressCallback

    self._windowName=windowName
    self._isWindowCreate=False

#檢查窗體是否被創建
@property
def isWindowCreated(self):
    return self._isWindowCreate

#創建窗體
def createWindow(self):
    cv2.namedWindow(self._windowName)
    self._isWindowCreate=True

#顯示圖像
def show(self,frame):
    cv2.imshow(self._windowName,frame)

#關閉窗體釋放資源
def destroyWindow(self):
    cv2.destroyWindow(self._windowName)
    self._isWindowCreate=False

#處理鍵盤事件
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
示例代碼如下:

!/usr/bin/env python

-- coding: utf-8 --

@Time : 2016/11/28 14:45

@Author : Retacn

@Site : cameo實現,有兩種啓動方法: 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-> 載圖
        tab->啓動和停止視頻錄製
        esc->退出應用

    :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()