如何从python中的现有二维数组数据创建灰度图像

Question

I have a problem creating a grey-scale image from existing 2D array in python.

Supposing I have a 2D array, X at dimension 504x896 data type is unit8. How could I create a gray-scale image from this 2D array? Will OpenCV provide an function for it or do I have to include other image processing library?

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I have tried this but it did not work for some reason. Given a 2D array z

dim = z.shape
h =  dim[0]
w = dim[1]

copy_image = np.zeros((h,w,1), np.uint8)
copy_image = z.copy();
cv2.imwrite("cpImage.bmp",copy_image)

Answer 1

This should work as expected. I have used Float32 as both arguments cv.CvtColor must have the same depth.

import numpy as np
import cv2
nArray = np.zeros((504, 896), np.float32) #Create the arbitrary input img
h,w = nArray.shape
cArray1 = cv2.CreateMat(h, w, cv2.CV_32FC3)
cArray2 = cv2.fromarray(nArray)
cv2.CvtColor(cArray2, cArray1, cv2.CV_GRAY2BGR)
cv2.imwrite("cpImage.bmp", cArray1)