Banuta Alin Alexandru Banuta Alin Alexandru - 1 month ago 11
Python Question

Python PIL: How can I set the background of an image(png) to white?

I have a png image with transparent background and I want to resize it to another image, but with white background instead of transparent one.
How can I do that with PIL?

Here is my code:

basewidth = 200
img = Image.open("old.png")
wpercent = (basewidth/float(img.size[0]))
hsize = int((float(img.size[1]) * float(wpercent)))
img = img.resize((basewidth, hsize), PIL.Image.ANTIALIAS)hsize = int((float(img.size[1]) * float(wpercent)))
img.save("new.png")


Update

import numpy as np
import PIL
from PIL import Image


basewidth = 200
img = Image.open("old.png")
wpercent = (basewidth/float(img.size[0]))
hsize = int((float(img.size[1]) * float(wpercent)))
data = np.array(img)

alpha1 = 0 # Original value
r2, g2, b2, alpha2 = 255, 255, 255,255 # Value that we want to replace it with

red, green, blue,alpha = data[:,:,0], data[:,:,1], data[:,:,2], data[:,:,3]
mask = (alpha==alpha1)
data[:,:,:4][mask] = [r2, g2, b2, alpha2]


img = Image.fromarray(data)
img = img.resize((basewidth,hsize), PIL.Image.ANTIALIAS)
img.save('new.png')


Here is the code provided by @khakishoiab and @Chachmu
Thanks guys!

Answer Source
import Image
from resizeimage import resizeimage

f = Image.open('old.png') 
alpha1 = 0 # Original value
r2, g2, b2, alpha2 = 255, 255, 255,255 # Value that we want to replace it with

red, green, blue,alpha = data[:,:,0], data[:,:,1], data[:,:,2], data[:,:,3]
mask = (alpha==alpha1)
data[:,:,:3][mask] = [r2, g2, b2, alpha2]

data = np.array(f)
f = Image.fromarray(data)
f = f.resize((basewidth,hsize), PIL.Image.ANTIALIAS)

f.save('modified.png', image.format)