彩色变换

import cv2
from skimage import data,color
from matplotlib import pyplot as plt
import numpy as np
L=255
def GetR(gray):
    if gray<L/2:
        return 0
    elif gray>L/4*3:
        return L
    else:
        return 4*gray-2*L
def GetG(gray):
    if gray<L/4:
        return 4*gray
    elif gray>L/4*3:
        return 4*L-4*gray
    else:
        return L
def GetB(gray):
    if gray<L/4:
        return L
    elif gray>L/2:
        return 0
    else:
        return 2*L-4*gray
img=cv2.imread('C:/Users/xpp/Desktop/Lena.png')#原始图像
cv2.imshow("original",img)
grayimg=color.rgb2gray(img) * 255#将彩色图片转换为灰度图片
colorimg=np.zeros(img.shape,dtype='uint8')
for ii in range(img.shape[0]):
    for jj in range(img.shape[1]):
        r,g,b=GetR(grayimg[ii,jj]),GetG(grayimg[ii,jj]),GetB(grayimg[ii,jj])#灰度值到彩色变换
        colorimg[ii,jj,:]=(r,g,b)
cv2.imshow("result",colorimg)        
cv2.waitKey()
cv2.destroyAllWindows()
plt.imshow(colorimg)