combine 3d arrays into a 4d array in numpy

Question

I have 3 images of the same size, I read each one using matplotlib.image.imread which returns a 3D numpy array.

(Height, Width, ChannelsNumber) # ChannelsNumber = 3 for RGB

Now, i want to merge the 3 images into a 4D numpy array like this:

(Height, Width, ChannelsNumber, NumberOfImages)

Meaning, the 3rd dimension array at position (X,Y) will no longer contain RGB values for pixel (X,Y) but will contain 3 arrays one for each channel (), where each array will contain 3 R, G, r B values (for 3 images)

• array at position X,Y,0 will contain all RED values for images 1,2,3 at pixel X,Y
• array at position X,Y,1 will contain all GREEN values for images 1,2,3 at pixel X,Y
• array at position X,Y,2 will contain all BLUE values for images 1,2,3 at pixel X,Y

For example:

(10,15,0) will be an array containing all the RED values for all the images for Pixel (10,15)

Here's what i have tried:

import numpy as np
import os
import matplotlib.image as mpimg

img1 = mpimg.imread('./image1.jpg')
img2 = mpimg.imread('./image2.jpg')
img3 = mpimg.imread('./image3.jpg')

x = np.dstack((img1, img2, img3))

this returns a 3D array, where the 3rd dimension is an array that contains the RGB values of the images in this format:

[R-img1, B-img1, G-img1, R-img2, B-img2, G-img2, R-img3, B-img3, G-img3]

where what i want is:

[ 
    [R-img1, R-img2, R-img3,],
    [R-img1, B-img2, -img3,],
    [B-img1, B-img2, B-img3,]
]

Thank you !

Answer 1

 import numpy as np import os import matplotlib.image as mpimg img1 = mpimg.imread('1.png') img2 = mpimg.imread('2.png') img3 = mpimg.imread('1.png') print(img1.shape) print(img2.shape) print(img3.shape) x = np.vstack((img1, img2, img3))

Stack arrays in sequence vertically

Answer 2

the answer is the one Scott commented

x = np.stack((img1, img2, img3), axis = -1)