[Numpy-discussion] ANN: qimage2ndarray - converting between QImages and numpy.ndarrays

Chris Colbert sccolbert@gmail....
Wed Dec 2 17:52:48 CST 2009


Cool. Thanks!

I will take a look at this. We have some code in scikits.image that
creates a QImage from the numpy data buffer for display. But I have
only implemented it for RGB888 so far. So you may have saved me some
time :)

Cheers!

Chris

2009/12/2 Hans Meine <meine@informatik.uni-hamburg.de>:
> Hi,
>
> I have just uploaded a first release of qimage2ndarray, a tiny python
> extension for quickly converting between QImages and numpy.ndarrays
> (in both directions).  These are very common tasks when programming e.g.
> scientific visualizations in Python using PyQt4 as the GUI library.
>
> Similar code was found in Qwt and floating around on mailing lists,
> but qimage2ndarray has the following unique feature set:
>
> * Supports conversion of scalar and RGB data, with arbitrary dtypes
>  and memory layout, with and without alpha channels, into QImages
>  (e.g. for display or saving using Qt).
>
> * Using a tiny C++ extension, qimage2ndarray makes it possible to
>  create ndarrays that are *views* into a given QImage's memory.
>
>  This allows for very efficient data handling and makes it possible
>  to modify Qt image data in-place (e.g. for brightness/gamma or alpha
>  mask modifications).
>
> * qimage2ndarray is stable and unit-tested:
>
>  * proper reference counting even with views (ndarray.base points to
>    the underlying QImage)
>
>  * handles non-standard widths and respects QImage's 32-bit row
>    alignment
>
> * Masked arrays are also supported and are converted into QImages
>  with transparent pixels.
>
> * Supports value scaling / normalization to 0..255 for convenient
>  display of arbitrary NumPy arrays.
>
> The extension is open source, BSD-licensed, and available via PyPI or here:
>
>  http://kogs-www.informatik.uni-hamburg.de/~meine/software/qimage2ndarray/
>
> I hope this is useful to many of you and look forward to your feedback,
>  Hans
>
> PS: Now that I am announcing this, I suddenly have the feeling that I should
> have talked with some lawyer (or Phil) about possible license issues because
> of PyQt.  I really hope there will not turn out to be problems with this.
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