Python +openCv 实现BGR2HSI和HSI2BGR

左手的ㄟ右手 2022-06-04 02:56 243阅读 0赞

关于转换原理参照[http://blog.sina.com.cn/s/blog\_6c41e2f30100xusj.html][http_blog.sina.com.cn_s_blog_6c41e2f30100xusj.html]

import cv2
    import numpy as np
    img=cv2.imread('C:/Users/53121/Desktop/IMAGE/road.jpg')
    
    
    #BGR转HSI，得到的HSI三通道取值范围都在0到1之间 
    def BGR2HSI(bgr_img):
        bgr=bgr_img.copy()
        B,G,R=cv2.split(bgr/255.0)
        hsi_img=bgr.copy()/255.0
        H,S,I=cv2.split(hsi_img)
        h,w=B.shape
        for i in range(h):
            for j in range(w):
                bgr_min=min(B[i,j],G[i,j],R[i,j])
                bgr_sum=B[i,j]+G[i,j]+R[i,j]
                I[i,j]=bgr_sum/3
                S[i,j]=1-3*bgr_min/bgr_sum
                cov=(R[i,j]-G[i,j])+(R[i,j]-B[i,j])
                var=2*np.sqrt((R[i,j]-G[i,j])**2+(R[i,j]-B[i,j])*(G[i,j]-B[i,j])**2)
                theta=np.arccos(cov/var)
                if G[i,j]>=B[i,j]:
                    H[i,j]=theta/(2*np.pi)
                else:
                    H[i,j]=(2*np.pi-theta)/(2*np.pi)  
        hsi_img[:,:,0]=H
        hsi_img[:,:,1]=S
        hsi_img[:,:,2]=I    
        return hsi_img
    
    #HSI转BGR,得到的BGR三通道取值范围都在0到1之间 
    def HSI2BGR(hsi_img):
        hsi=hsi_img.copy()
        H,S,I=cv2.split(hsi)
        bgr_img=hsi_img.copy()
        B,G,R=cv2.split(bgr_img)
        h,w=B.shape
        for i in range(h):
            for j in range(w):            
                if S[i,j]<1e-6:
                    R[i,j]=I[i,j]
                    G[i,j]=I[i,j]
                    B[i,j]=I[i,j]
                else:
                    H[i,j]*=360          
                    if H[i,j]>0 and H[i,j]<=120:
                        B[i,j]=(1-S[i,j])*I[i,j]
                        sigma=(H[i,j]-60)*np.pi/180
                        temp=np.tan(sigma)/np.sqrt(3)
                        G[i,j]=(1.5+1.5*temp)*I[i,j]-(0.5+1.5*temp)*B[i,j]
                        R[i,j]=3*I[i,j]-G[i,j]-B[i,j]
                    elif H[i,j]>120 and H[i,j]<=240:
                        R[i,j]=(1-S[i,j])*I[i,j]
                        sigma=(H[i,j]-180)*np.pi/180
                        temp=np.tan(sigma)/np.sqrt(3)
                        B[i,j]=(1.5+1.5*temp)*I[i,j]-(0.5+1.5*temp)*R[i,j]
                        G[i,j]=3*I[i,j]-R[i,j]-B[i,j]
                    elif H[i,j]>240 and H[i,j]<=360:
                        G[i,j]=(1-S[i,j])*I[i,j]
                        sigma=(H[i,j]-300)*np.pi/180
                        temp=np.tan(sigma)/np.sqrt(3)
                        R[i,j]=(1.5+1.5*temp)*I[i,j]-(0.5+1.5*temp)*G[i,j]
                        B[i,j]=3*I[i,j]-G[i,j]-R[i,j]
        bgr_img[:,:,0]=B
        bgr_img[:,:,1]=G
        bgr_img[:,:,2]=R
        return bgr_img
    
    hsi=BRG2HSI(img)
    bgr=HSI2BGR(hsi)

[http_blog.sina.com.cn_s_blog_6c41e2f30100xusj.html]: http://blog.sina.com.cn/s/blog_6c41e2f30100xusj.html