Well after some digging through the PIL source code after the prompting
from Douglas, and some tinkering with the python C interface, I have
implemented a C based version of the core pixel setting loop using PIL
objects. I have also added 'reference' versions using plain python,
setting an
John Barratt wrote:
I haven't tried it, but did originally think of adding it to the list of
things tested. Given this specific example though, where the idea is
that a specific method or piece of code is needed to be run for every
pixel (not that it actually is in this abstract example),
Hi Chris,
Christopher Barker wrote:
I think where PIL numpy would excel is where you have a cases of a
number of images with calculations required that could be easily
represented as array operations. The examples I am thinking of don't
lend themselves to this sort of solution.
Also
Hi Douglas,
Douglas Bagnall wrote:
um.. cache locality? With GD you have
for (u=0; ux; u++) {
for (v=0; vy; v++) {
d[v][u] = colour;
}
}
which goes through every row for each column, jumping back and forth in
memory. You need to switch the order of the loops, like
Christopher Barker wrote:
John Barratt wrote:
I've had a need to do some optimisation of some low level pixel setting
code, and have as such done some tests of different ways of doing this
using PIL and alternatively with gd via ctypes.
Have you tried using PIL + numpy -- you can
With prompting from Chris, and a little further work in gd, I have
updated this comparison further, adding a further gd/ctypes test, this
time setting pixel values using the raw pixel data, as well as the start
of a test for a numpy/PIL option. Unfortunately it doesn't fully work,
at least
hi John,
Method Time (s)Times slower than fastest
+-+ +---+ ++
ctypes,c,GD raw 0.00082 1.0
ctypes,c,GD 0.00177 2.2
PIL - 'load'0.03226 39.4
ctypes, GD 0.14428 176.4
PIL, numpy *
Hi Douglas,
Douglas Bagnall wrote:
Method Time (s)Times slower than fastest
+-+ +---+ ++
ctypes,c,GD raw 0.00082 1.0
ctypes,c,GD 0.00177 2.2
PIL - 'load'0.03226 39.4
ctypes, GD 0.14428
