how to reduce png image filesize in PIL

Question

I have used PIL to convert and resize JPG/BMP file to PNG format. I can easily resize and convert it to PNG, but the file size of the new image is too big.

im = Image.open('input.jpg')
im_resize = im.resize((400, 400), Image.ANTIALIAS)  # best down-sizing filter
im.save(`output.png')

What do I have to do to reduce the image file size?

possible duplicate of [Optimize .png images with PIL](http://stackoverflow.com/questions/1991929/optimize-png-images-with-pil) — Martijn Pieters, Aug 13 '12 at 08:05
Also: [How to reduce the image file size using PIL](http://stackoverflow.com/q/10607468) — Martijn Pieters, Aug 13 '12 at 08:06
Last but not least, set the `optimize` option when saving: `im.save(filename, optimize=True)` — Martijn Pieters, Aug 13 '12 at 08:09

score 4 · Accepted Answer · answered Aug 13 '12 at 12:39

PNG Images still have to hold all data for every single pixel on the image, so there is a limit on how far you can compress them.

One way to further decrease it, since your 400x400 is to be used as a "thumbnail" of sorts, is to use indexed mode:

im_indexed = im_resize.convert("P") im_resize.save(... )

*wait * Just saw an error in your example code: You are saving the original image, not the resized image:

im=Image.open(p1.photo)
im_resize = im.resize((400, 400), Image.ANTIALIAS)    # best down-sizing filter
im.save(str(merchant.id)+'_logo.'+'png')

When you should be doing:

im_resize.save(str(merchant.id)+'_logo.'+'png')

You are just saving back the original image, that is why it looks so big. Probably you won't need to use indexed mode them.

Aother thing: Indexed mode images can look pretty poor - a better way out, if you come to need it, might be to have your smalle sizes saved as .jpg instead of .png s - these can get smaller as you need, trading size for quality.

score 0 · Answer 2 · answered Aug 13 '12 at 08:27

0

You can use other tools like PNGOUT

answered Aug 13 '12 at 08:27

Vivek S

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how to reduce png image filesize in PIL

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