Description

An IMMENSELY FAST JPEG thumbnailer library API.

Why write this? It’s a convenience library API to using libjpeg to load JPEG images destined to be turned into thumbnails of the original, saving information with these thumbnails, retreiving it and managing to load the image ready for scaling with the minimum of fuss and CPU overhead.

This means it’s insanely fast at loading large JPEG images and scaling them down to tiny thumbnails. It’s speedup will be proportional to the size difference between the source image and the output thumbnail size as a count of their pixels.

It makes use of libjpeg features of being able to load an image by only decoding the DCT coefficients needed to reconstruct an image of the size desired. This gives a massive speedup. If you do not try and access the pixels in a format other than YUV (or GRAY8 if the source is grascale) then it also avoids colorspace conversions as well.

epeg source: https://github.com/mattes/epeg

This module provides Python bindings via CFFI.

Usage

In [1]: import epeg
In [2]: thumbnail_data = epeg.scale_image(
    fname,   # Path to source JPEG image
    width,   # Desired thumbnail width
    height,  # Desired thumbnail height
    quality  # Desired quality, default: 75)

Benchmarks

In [1]: from wand.image import Image
In [2]: %timeit Image(filename='/tmp/007.jpg'); img.sample(800, 600); _ = img.make_blob('jpeg')
1 loops, best of 3: 264 ms per loop

In [1]: from PIL import Image
In [2]: %timeit Image.open('/tmp/007.jpg').resize((800, 600)).save('/tmp/foo_thumb.jpg')
1 loops, best of 3: 234 ms per loop

In [1]: import epeg
In [2]: %timeit epeg.scale_image('/tmp/007.jpg', 800, 600)
10 loops, best of 3: 101 ms per loop