From this page you can download the drizzling software library, drizzlib, which reprojects data from HEALPix to local WCS FITS format. The current library is available in Python3. Older versions in Python2 and IDL are available, but no longer actively maintained.

The drizzling library uses a strategy where the surface of pixel intersection is computed as presented in Appendix A of Paradis et al., 2012, A&A, 543, 103. This method allows fast ingestion and guarantees the photometric accuracy of the transformation with minimal data loss during the transformation from HEALPix to local WCS FITS.

CADE also offers a web interface to the drizzling software library called drizzweb. This allows the user to reproject data from HEALPix to local WCS FITS format using CADE's computing resources. The drizzweb page is here http://drizzweb.irap.omp.eu/

Python version


  • Antoine Goutenoir (IRAP)
  • Déborah Paradis (IRAP)
  • Jean-Michel Glorian (IRAP)
  • Gabriel Foënard (IRAP)
  • Nathanael Jourdane (IRAP)
  • Anaïs Amato (IRAP)
  • Annie Hughes (IRAP)

Where to download the drizzlib python code

CADE supports several options for getting access to drizzlib-python: git, pip and direct download of the source tarball.

The python package can be downloaded and installed via pip (recommended):

pip install drizzlib

The source tree is available on gitlab .

Or you can directly grab a tarball here :

:!: There are detailed instructions and troubleshooting tips in the README, which you should read.

Installation Details

First, install the system dependencies :

Debian / Ubuntu
apt-get install python-dev pkg-config libfreetype* gfortran libopenblas-dev liblapack-dev

Using pip

pip install drizzlib
:?: It may complain about numpy. Install it, and try again.

From source

Uncompress the tarball, move into the newly created directory (e.g. drizzlib-2.0)

Then, install drizzlib using pip:

pip install --editable .

Using the drizzlib python code : simple example

Here's a simple usage example that reads my_healpix.fits, extracts a subset of its data as described by the header in wcs_config.fits, and writes the result into my_wcs.fits :

from drizzlib.healpix2wcs import healpix2wcs

Older versions of the drizzlib library (python 2.7 only)

IDL version


  • Jean-Philippe Bernard (IRAP)
  • Nathalie Baby (IRAP)
  • Caroline Bot (CDS)
  • Laurent Cambrésy (CDS)
  • Déborah Paradis (IRAP)
  • Alexandre Sauvé (IRAP)