Pasting image with Alpha transpency

Question

I have a piece of code that takes a string and constructs a graffiti-like image from that string. The letters are all individual .PNG images that are read in and pasted onto a new, longer image. My problem is that while the background alpha channel is in fact preserved, where the letters overlap it is not. Please see image.

How can I paste these letters overlapping while preserving alpha channel? It seems that both alpha_composite and blend functions need identical images to work.

It should be noted that I can do this either in Python or C++, I just used python now because it seemed very fast and easy.

IMAGE of problem

One original letter

EDIT: Here is the code. For sure there must be better ways to do this.

import sys
from PIL import Image


def openLetters(letters):

    files = {
        'A': 'A-rens.png',
        'B': 'B-rens.png',
        'C': 'C-rens.png',
        'D': 'D-rens.png',
        'E': 'E-rens.png',
        'F': 'F-rens.png',
        'G': 'G-rens.png',
        'H': 'H-rens.png',
        'I': 'I-rens.png',
        'J': 'J-rens.png',
        'K': 'K-rens.png',
        'L': 'L-rens.png',
        'M': 'M-rens.png',
        'N': 'N-rens.png',
        'O': 'O-rens.png',
        'P': 'P-rens.png',
        'Q': 'Q-rens.png',
        'R': 'R-rens.png',
        'S': 'S-rens.png',
        'T': 'T-rens.png',
        'U': 'U-rens.png',
        'V': 'V-rens.png',
        'W': 'W-rens.png',
        'X': 'X-rens.png',
        'Y': 'Y-rens.png',
        'Z': 'Z-rens.png',
    }



    images = []
    for letter in letters:
        images.append(Image.open(files[letter]))
        print "Opened:" + files[letter]


    widths, heights = zip(*(i.size for i in images))

    totalWidth = sum(widths)
    maxHeight = max(heights)

    newImage = Image.new('RGBA', (totalWidth, maxHeight))

    x_offset = 0

    for im in images:
        newImage.paste(im, (x_offset, 0), mask=0)
        x_offset += im.size[0] - 200

    newImage.save(letters + ".png")


openLetters("ANDERS")

Answer 1

If, as it sounds, you just want the easiest way, I would suggest ImageMagick which is installed on most Linux distros and is available for macOS and Windows. Just in Terminal or at Command Prompt:

magick a.png a.png a.png +smush -140  result.png

Change from +smush to -smush to append vertically. Increase the 140 to overlap more, or decrease it to overlap less.

---

If your ImageMagick version is older than v7, replace magick in my command with convert.

---

As you didn't give me enough letters to play with, you'll have to make do with this for your Python version:

#!/usr/bin/env python3

import sys
from PIL import Image


w = 3000
h = 1490

newImage = Image.new('RGBA', (w, h))
myMiserableA = Image.open('a.png').convert('RGBA')

x_offset = 0

for im in range(3):
    newImage.paste(myMiserableA, (x_offset, 0), mask=myMiserableA)
    x_offset += 1000

newImage.save('result.png')