pylibjpeg

A Python 3.6+ framework for decoding JPEG images, with a focus on providing JPEG support for pydicom.

Installation

Installing the current release

pip install pylibjpeg

Installing the development version

Make sure Git is installed, then

git clone https://github.com/pydicom/pylibjpeg
python -m pip install pylibjpeg

Plugins

By itself pylibjpeg is unable to decode any JPEG images, which is where the plugins come in. To support a given JPEG format or DICOM Transfer Syntax you first have to install the corresponding package:

JPEG Format

Format	Decode?	Encode?	Plugin	Based on
JPEG, JPEG-LS and JPEG XT	Yes	No	pylibjpeg-libjpeg	libjpeg

Transfer Syntax

UID	Description	Plugin
1.2.840.10008.1.2.4.50	JPEG Baseline (Process 1)	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.51	JPEG Extended (Process 2 and 4)	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.57	JPEG Lossless, Non-Hierarchical (Process 14)	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.70	JPEG Lossless, Non-Hierarchical, First-Order Prediction (Process 14, Selection Value 1)	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.80	JPEG-LS Lossless	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.81	JPEG-LS Lossy (Near-Lossless) Image Compression	pylibjpeg-libjpeg
1.2.840.10008.1.2.4.90	JPEG 2000 Image Compression (Lossless Only)	Not yet supported
1.2.840.10008.1.2.4.91	JPEG 2000 Image Compression	Not yet supported

If you're not sure what the dataset's Transfer Syntax UID is, it can be determined with:

>>> from pydicom import dcmread
>>> ds = dcmread('path/to/dicom_file')
>>> ds.file_meta.TransferSyntaxUID.name

Usage

With pydicom

Assuming you already have pydicom installed:

from pydicom import dcmread
from pydicom.data import get_testdata_file

# With the pylibjpeg-libjpeg plugin installed
import pylibjpeg

ds = dcmread(get_testdata_file('JPEG-LL.dcm'))
arr = ds.pixel_array

For datasets with multiple frames you can reduce your memory usage by processing each frame separately using the generate_frames() generator function:

from pydicom import dcmread
from pydicom.data import get_testdata_file

from pylibjpeg import generate_frames

ds = dcmread(get_testdata_file('color3d_jpeg_baseline.dcm'))
frames = generate_frames(ds)
arr = next(frames)

Standalone JPEG decoding

You can also just use pylibjpeg to decode JPEG images to a numpy ndarray, provided you have a suitable plugin installed:

from pylibjpeg import decode

# Can decode using the path to a JPG file as str or pathlike
arr = decode('filename.jpg')

# Or a file-like...
with open('filename.jpg', 'rb') as f:
    arr = decode(f)

# Or bytes...
with open('filename.jpg', 'rb') as f:
    arr  = decode(f.read())