Fastest Way To Loop Through Every Pixel

[John Machin]

Chaos wrote:
> As my first attempt to loop through every pixel of an image, I used
>
>         for thisY in range(0, thisHeight):
>             for thisX in range(0, thisWidth):
>                   #Actions here for Pixel thisX, thisY

OT: you don't need the 0 in the range call. Taking it out doesn't make
it run faster, though.

>
> But it takes 450-1000 milliseconds
>
> I want speeds less than 10 milliseconds
>
> I have tried using SWIG, and pypy but they all are unsuccessfull in
> compiling my files.

Unsuccessful because .... what?
[I wasn't aware that swig was intended to compile Python scripts]

Sticking with Python:
With the "for thisX" try
(1) using xrange instead of range.
(2)     widthRange = range(thisWidth)
         for thisY in range(thisHeight):
             for thisX in widthrange:
and in general, hoist loop-invariants outside the loop.

Have you considered Pyrex?

It all depends on what "#Actions here for Pixel thisX, thisY" is doing.
Perhaps there is a library (PIL, pygame, ...) that does what you are
trying to do.
Perhaps if you show us what you are doing, we can give you better
advice.

HTH,
John