Python PIL, preserve quality when resizing and saving [duplicate]

Question

I have a large image, which I resize in PIL so that it is 250 pixels wide. This is the width that it will be shown on my website.

However, the resolution is really bad. I see that it has changed the dpi from 180 to 96. If I resize the image in a program like Windows Paint then it maintains the 180 dpi. This Paint-resized image looks a lot better on my website. (The paint-resized image is 40kb while the PIL resized image is 16kb)

How do I maintain the dpi (or set it to some max that looks good on websites)

I resize this using PIL:

image = image.resize((new_width, new_height), Image.ANTIALIAS)
image.save(filepath)

I have tried:

dpi = image.info['dpi']  # (180, 180)
image.save(filepath, dpi = dpi) 

but it makes no difference. The dpi is 180, but the resolution is still bad. I'm guessing that the dpi needs to be set during resizing?

EDIT:

The issue seems to be the saving, not the resizing. Even if I start with the Paint-resized image (and therefore do not resize the image in PIL), it still saves it as the crappy quality 96 dpi (16kb) intead of keeping it as it is.

Answer 1

Thanks to the discussion with abarnert, I (he) realized that the issue was the saving, not the resizing.

And then I was able to find this, which solved the issue:

image_fullsize.save(filepath+name_fullsize, quality=95)

from here: How to adjust the quality of a resized image in Python Imaging Library?