Convert png to jpeg using Pillow

Question

I am trying to convert png to jpeg using pillow. I've tried several scrips without success. These 2 seemed to work on small png images like this one.

First code:

from PIL import Image
import os, sys

im = Image.open("Ba_b_do8mag_c6_big.png")
bg = Image.new("RGB", im.size, (255,255,255))
bg.paste(im,im)
bg.save("colors.jpg")

Second code:

image = Image.open('Ba_b_do8mag_c6_big.png')
bg = Image.new('RGBA',image.size,(255,255,255))
bg.paste(image,(0,0),image)
bg.save("test.jpg", quality=95)

But if I try to convert a bigger image like this one

I'm getting

Traceback (most recent call last):
  File "png_converter.py", line 14, in <module>
    bg.paste(image,(0,0),image)
  File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 1328, in paste
    self.im.paste(im, box, mask.im) ValueError: bad transparency mask

What am i doing wrong?

Have you tried [this](http://stackoverflow.com/questions/7911451/pil-convert-png-or-gif-with-transparency-to-jpg-without)? — Sangbok Lee, Apr 06 '17 at 15:03

score 158 · Accepted Answer · answered Apr 06 '17 at 15:05

158

You should use convert() method:

from PIL import Image

im = Image.open("Ba_b_do8mag_c6_big.png")
rgb_im = im.convert('RGB')
rgb_im.save('colors.jpg')

more info: http://pillow.readthedocs.io/en/latest/reference/Image.html#PIL.Image.Image.convert

answered Apr 06 '17 at 15:05

dm2013

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But it is making the white background of the image white. Is there any way to fix it. – lifeisshubh Apr 04 '19 at 13:31
11

@lifeisshubh are white supposed to be converted into black?! – Anna Nov 14 '19 at 23:34
4

I laughed so hard at this. @lifeisshubh Did you mean "it is making the white background of the image black?" – Nathan majicvr.com Jan 28 '20 at 17:41
@frank I mean what you have written. – lifeisshubh Jan 29 '20 at 07:44
@lifeisshubh Can you replicate the bug? I'm sure [they'd like to know](https://github.com/python-pillow/Pillow), especially if a lot of people have the same issue. There might also be someone with your same issue who has fixed it :) – Nathan majicvr.com Jan 29 '20 at 14:35
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As far as I remember it got resolved. But it's been a long time, I neither have that system on which I was working, nor that code. Time fades things away. – lifeisshubh Jan 29 '20 at 14:52
Here colors.jpg store in particular local path can you give me an example? – arun kumar Mar 16 '20 at 06:55
@arunkumar normally I'm not a stickler for grammar, but in this case I literally can't understand your comment. Are you saying the OP's code worked for you? – Nathan majicvr.com Apr 09 '20 at 06:32
I have a BIG issue when trying to convert large a grayscale 16bit PNG to compress it. The code is quite simple but all what I get is just a white sheet. The original large PNG file can be found at https://postimg.cc/p5PQG8ry the code is: from PIL import Image im = Image.open('terzafoto.png').convert('RGB') im.save('terzafoto.jpg', format='JPEG', quality=100) – GBBL May 11 '21 at 11:42
I had to do `image.convert('RGB')` followed by `image.mode = 'RGB'` – default123 Jul 23 '21 at 03:12

score 23 · Answer 2 · answered Apr 06 '17 at 15:15

The issue with that image isn't that it's large, it is that it isn't RGB, specifically that it's an index image.

Here's how I converted it using the shell:

>>> from PIL import Image
>>> im = Image.open("Ba_b_do8mag_c6_big.png")
>>> im.mode
'P'
>>> im = im.convert('RGB')
>>> im.mode
'RGB'
>>> im.save('im_as_jpg.jpg', quality=95)

So add a check for the mode of the image in your code:

if not im.mode == 'RGB':
  im = im.convert('RGB')

score 21 · Answer 3 · edited Aug 12 '17 at 01:14

21

You can convert the opened image as RGB and then you can save it in any format. The code will be:

from PIL import Image
im = Image.open("image_path")
im.convert('RGB').save("image_name.jpg","JPEG") #this converts png image as jpeg

If you want custom size of the image just resize the image while opening like this:

im = Image.open("image_path").resize(x,y)

and then convert to RGB and save it.

The problem with your code is that you are pasting the png into an RGB block and saving it as jpeg by hard coding. you are not actually converting a png to jpeg.

edited Aug 12 '17 at 01:14

Cory Madden

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answered Apr 06 '17 at 15:05

Mani

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all answers are good, thank you, but any ideea how you can compress the size aswell? – alex Apr 06 '17 at 15:26
Try optimize=True while saving the image. – Mani Apr 07 '17 at 01:45

score 3 · Answer 4 · answered Feb 12 '19 at 13:37

if you want to convert along with resize then try this,

from PIL import Image

img = i.open('3-D Tic-Tac-Toe (USA).png').resize((400,400)) # (x,y) pixels
img.convert("RGB").save('myimg.jpg')

thats it.. your resized and converted image will store in same location

Convert png to jpeg using Pillow

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