CODEWITHSUNDEEP
pythonnumpyopencvpython-imaging-library
Jolanthan
Jolanthan

Reputation: 81

How to merge/append/stack/paste all images in folder vertically to a new image

I would like to merge all pictures in a folder and have them stacked, appended horizontally.

import os
from PIL import Image
allfiles = os.listdir(os.getcwd())
imlist =[filename for filename in allfiles if filename[-4:] in [".png", ".PNG"]]
N = len(imlist)
w, h = Image.open(imlist[0]).size

total_width = w * N
max_height = h

new_im = Image.new('RGB', (total_width, max_height))

for i in range(1,N):
    img = Image.open(imlist[i])
    offset = 0
    appendedimages.paste(img, (x_offset,0))
    offset += img.size[0]

appendedimages.save('test.jpg')

It seems, that using this, it only displays the last image. Does someone know why that happens?

I have also tried

import cv2
import os
import numpy as np


allfiles = os.listdir(os.getcwd())
imlist =[filename for filename in allfiles if filename[-4:] in [".png", ".PNG"]]
N = len(imlist)
for i in range(1,N):
    img = cv2.imread(imlist[i])

horizontalAppendedImg = np.hstack(img)
cv2.imshow('Horizontal Appended', horizontalAppendedImg)
cv2.waitKey(0)
cv2.destroyAllWindows()

But that also doesn't work.

Can anyone help me with this? Or is there a simpler solution to this?

Upvotes: 0

Views: 973

Answers (1)

Dorian
Dorian

Reputation: 1488

images are numpy arrays. As long as they have the same dimensions, you can np.hstack them.

imlist =[cv2.imread(filename) for filename in allfiles if filename[-4:] in [".png", ".PNG"]]
concat_img = np.hstack(imlist)

cv2.imshow('Horizontal Appended', concat_img)
cv2.waitKey(0)
cv2.destroyAllWindows()

Explanation:

  • read in all images into a list with list comprehension: list of images/np.arrays
  • use np.hstack() to concatenate all images along the horizontal dimension. You could use more general concatenation tools with np.concatenate() or np.stack() if you run into issues.

Upvotes: 2

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