详解Python中常用的图片处理函数的使用
目录
- cvtColor函数
- split()和merge()
- threshold()函数
- 自定义threshold函数进行二值化
- 色度函数applyColorMap
cvtColor函数
这个函数有两个参数
1,src 要进行变换的原图像
2,code 转换代码标识
例子:
import cv2 image=cv2.imread("ddd.jpg") image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA) cv2.imshow("",image1) cv2.waitKey(0) if __name__ == '__main__': print()
split()和merge()
例子:
import cv2 image=cv2.imread("ddd.jpg") # image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA) r,g,b=cv2.split(image) cv2.imshow("r",r) cv2.imshow("g",g) cv2.imshow("b",b) cv2.waitKey(0) if __name__ == '__main__': print()
import cv2 image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg") # image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA) r,g,b=cv2.split(image) cv2.imshow("r",r) cv2.imshow("g",g) cv2.imshow("b",b) image1=cv2.merge([b,g,r]) cv2.imshow("image",image1) cv2.waitKey(0) if __name__ == '__main__': print()
threshold()函数
ret,image= cv2.threshold(src,thresh,maxval,type)
实现二值化的重要函数
参数说明
src
输入图像
image
输出图像
thresh
阀值
maxval
当像素值超过阀值thresh 时赋值为maxval
type
当像素值小于阀值thresh的时赋值为type type可填下面5种类型的参数
例子:
import cv2 image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg") # image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA) # r,g,b=cv2.split(image) # cv2.imshow("",r) # cv2.imshow("",g) # cv2.imshow("",b) # image1=cv2.merge([b,g,r]) # cv2.imshow("image",image1) ret,image1=cv2.threshold(image,127,255,cv2.THRESH_BINARY) ret1,image2=cv2.threshold(image,127,255,cv2.THRESH_BINARY_INV) # ret2,image3=cv2.threshold(image,127,255,cv2.THRESH_TRIANGLE) ret3,image4=cv2.threshold(image,127,255,cv2.THRESH_TOZERO) ret4,image5=cv2.threshold(image,127,255,cv2.THRESH_TOZERO_INV) cv2.imshow("1",image1) cv2.imshow("2",image2) # cv2.imshow("3",image3) cv2.imshow("4",image4) cv2.imshow("5",image5) cv2.waitKey(0) if __name__ == '__main__': print()
自定义threshold函数进行二值化
import cv2 image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg") width,height,n=image.shape image2=image.copy() for i in range(width): for j in range(height): for channel in range(3): if image2[i][j][channel]>127: image2[i][j][channel]=255 else: image2[i][j][channel]=0 cv2.imshow('',image2) cv2.waitKey(0) if __name__ == '__main__': print()
这个速度很慢对于分辨率太高的图
色度函数applyColorMap
import cv2 image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg") image_color_map=cv2.applyColorMap(image,cv2.COLORMAP_JET) cv2.imshow("im",image_color_map) cv2.waitKey(0) if __name__ == '__main__': print()
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