That says what needs saying, but it's rather a convoluted sentence.
If you changed "providing" to a full finite verb, that would make it
a bit less deeply embedded:
Based on PyQwt (plotting widgets for PyQt4 graphical user interfaces)
and on the scientific modules NumPy and SciPy, guiqwt is a Python library
that provides efficient 2D data-plotting features (curve/image visualization
and related tools) for signal/image processing application development and
interactive computing.
(I've also moved "interactive computing" so that it can't be read as
"for interactive computing app development and signal/image
processing app development".)
Part of the trouble is the preposed "Based on..." - it neatly avoids
having to start the sentence with lowercase "guiqwt", but it makes
it harder to tweak. If I'm allowed to rip it apart completely and
reassemble it "backwards", I get:
The guiqwt Python library provides efficient 2D data-plotting features
(curve/image visualization and related tools) for signal/image processing
application development and interactive computing. It's based on the
scientific modules NumPy and SciPy, and the PyQwt plotting widgets for
PyQt4 graphical user interfaces.
I can't tell which of these I prefer.