How can I make empty grayscale image in OpenCV Python?

Question

I want to know how to make a empty grayscale image in OpenCV.

First, I know how to make a empty 'color image' like this.

import cv2  
import numpy as np
blank_image = np.zeros((height,width,3), dtype = np.uint8)

Then, how can I make a empty 'grayscale' image with specific height and width?

Answer 1

I want to know how to make a empty grayscale image in OpenCV.

First, I know how to make a empty 'color image' like this.

import cv2  
import numpy as np
blank_image = np.zeros((height,width,3), dtype = np.uint8)

Then, how can I make a empty 'grayscale' image with specific height and width?

Answer 2

I want to know how to make a empty grayscale image in OpenCV.

First, I know how to make a empty 'color image' like this.

import cv2  
import numpy as np
blank_image = np.zeros((height,width,3), dtype = np.uint8)

Then, how can I make a empty 'grayscale' image with specific height and width?

Answer 3

Can i ask then, how do you save it as a greyscale png file? When i compile i get an error

import cv2' import numpy as np' height = 121' width = 121' grey_Value = 16 greyimage = np.full(height, width), grey_Value, np.uint16' cv2.imwrite('e:\\Cutfill\\test.png',greyimage)'

cv2.imwrite('e:\\Cutfill\\test.png',greyimage) cv2.error: OpenCV(4.5.4) :-1: error: (-5:Bad argument) in function 'imwrite'

Overload resolution failed:

• img is not a numerical tuple
• Expected Ptr<cv::UMat> for argument 'img'