imgsize

Pure Python library to get the size of image files. Supports JPG, PNG, GIF and BMP, though some files in those formats may not be supported.

Why

For fun. Also, because if all you need is the size of an image, pulling in Pillow is overkill. While Pillow is a fantastic library, it relies on quite a few C libraries, making it a somewhat "heavy" dependency. If you need to work with images, it's great, but if all you need is the size, maybe something a bit more lightweight is more suited.

It is also quite a bit faster than Pillow (for getting the size), as it does no actual decoding of image data and stops doing anything as soon as the size information is found.

Benchmarks

Note that benchmarks are a lie. But for what it's worth, here's the time it took on my machine to read the image size of four different formats 10'000 times:

format	imgsize	pillow	speedup
jpg	0.3220	1.1276	3.50x
png	0.2856	0.8805	3.08x
gif	0.2052	0.9481	4.62x
bmp	0.2435	0.6003	2.46x

Usage

import io

from imgsize import get_size

with io.open('/path/to/your/image', 'rb') as fobj:
    width, height = get_size(fobj)

You can also use it from the command line using python -m imgsize <path>.

Extend

You can extend imgsize with new formats. In this example, we assume an image format with the magic number 0x64 0x78 0x61 0x6d 0x70 0x6c 0x65, followed by an unsigned int for the width, followed by an unsigned int for the height. All values are little-endian.

For that format, we would write this class:

import struct

from imgsize.formats import signature, Struct

Size = Struct('<II')

@signature('Example', struct.pack('<BBBBBBB', 0x64, 0x78, 0x61, 0x6d, 0x70, 0x6c, 0x65))
def get_size_example(cls, fobj):
    return Size.unpack_from(fobj)

Now to use it (together with the built-in formats), use this code:

from imgsize.core import ImageSize
from imgsize.formats import jpg, gif, png, bmp

imgsize = ImageSize()
imgsize.register(jpg.get_size)
imgsize.register(gif.get_size)
imgsize.register(png.get_size)
imgsize.register(bmp.get_size)
imgsize.register(get_size_example)

with io.open('/path/to/image', 'rb') as fobj:
    width, height = imgsize.get_size(fobj)