Python envelope for the popular C library libjpeg for handling JPEG files.
Project description
jpeglib
Python envelope for the popular C library libjpeg for handling JPEG files.
libjpeg offers full control over compression and decompression and exposes DCT coefficients and quantization tables.
Installation
Simply install the package with pip3
pip install jpeglib
Usage
Import the library in Python 3
import jpeglib
To install the dev version with all the libjpeg versions inside, type
pip uninstall jpeglib
pip install -U --no-cache-dir git+https://www.github.com/martinbenes1996/jpeglib.git@versions
:warning: Branch versions is dev so it is less stable and takes longer to install than the package.
DCT
Get discrete cosine transform (DCT) coefficients and quantization matrices as numpy array
im = jpeglib.JPEG("input.jpeg") # load metadata
Y,CbCr,qt = im.read_dct() # load data
You get luminance DCT, chrominance DCT and quantization tables.
Write the DCT coefficients back to a file with
im.write_dct("output.jpeg", Y, CbCr) # write data
You can also write the read-write sequence using with statement
with jpeglib.JPEG("input.jpeg") as im:
Y,CbCr,qt = im.read_dct()
# modify the DCT coefficients
im.write_dct("output.jpeg", Y, CbCr)
Pixel data
Decompress the input.jpeg into spatial representation in numpy array with
im = jpeglib.JPEG("input.jpeg")
rgb = im.read_spatial()
You can specify parameters such as output color space, DCT method, dithering, etc.
Write spatial representation in numpy arrray back to file with
im.write_spatial("output.jpeg", spatial)
Here you can specify input color space, DCT method, sampling factor, output quality, smoothing factor etc.
You can find all the details in the documentation.
libjpeg version
It is possible to choose, which version of libjpeg should be used.
jpeglib.version.set('6b')
Currently jpeglib supports the most popular versions 6b and 8d. Their source codes is baked inside the package
and thus distributed with it, avoiding external dependency.
Get currently used libjpeg version by
version = jpeglib.version.get()
Credits
Developed by Martin Benes.
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