P: n/a

Hi.
Regarding your question about PNGwriter versus plain libpng, yes,
basically PNGwriter offers much greater ease of use. If you're an
experienced programmer and just need a simple PNG read or write
function, then surely reading libpng's documentation and throwing
together a PNG reader or writer of your own is something you could do
three times before breakfast :-) (it took me quite a bit longer than
that, I can tell you).
But for the rest of us mere mortals, something slightly more abstract
and easier to use is welcome. As you can see from the feature list that
I posted previously, PNGwriter goes beyond just writing and reading
PNGs in an intuitive and simpe way (via the plot() and read() member
functions), and thus offers the possibility of doing things that you
can just as easily do with libpng, but saving you the work of coding it
yourself. Further pursuit of this explanation would no doubt lead us to
a description of what libraries are for, and thus be rather redundant.
:-)
To illustrate my point, compare the shortest PNG-reading code fragment
using libpng to the equivalent code using PNGwriter. PNGwriter wraps
all that code into one function, thus requiring one line to load a PNG
file.
So, basically, if you feel PNGwriter might be useful to you (visiting
the website would be a good starting point) please go ahead, I will
lend my support via the mailing list however I can. If on the other
hand, you are comfortable using libpng directly, go ahead; that is the
beauty of having a choice.
Best of luck,
Paul Blackburn