[wxpython-users] Fast(er) pixel level access

[Folkert Boonstra]

Folkert Boonstra schreef:
> Christopher Barker schreef:
>   
>> Folkert Boonstra wrote:
>>     
>>> Just an update on how far i got with getting it faster.
>>> Replacing loops with list comprehensions is a major enhancement:
>>>       
>> I'm a bit surprised -- I thought list comprehensions gave you almost
>> the same byte code. I learn something new every day.
>>
>> Anyway, you can easily get a 10X or so speed up for this kind  of
>> thing with numpy -- it really is the tool for the job, it's well worth
>> learning
Chris,

Thanks for your suggestion(s)!. It is now fast enough for 512x512 size
images.
Now I have to look at the drawing of bitmaps again.
The rules are now implemented solely with numpy. The lichenWithDeath
rule is ugly currently (although still fast). Is there a way to do the
convolve only once?

    def parity(self):
        kernel = NU.array([[0,1,0],[1,1,1],[0,1,0]]).astype(NU.uint8)
        mask   = (NI.convolve(self.bufbw, kernel) == 1).astype(NU.uint8)
        self.bufbw = mask
        self.buf = NU.array(self.DA, copy=1)
        NU.putmask(self.buf, mask, self.LA)
                    
    def life(self):
        kernel = NU.array([[1,1,1],[1,0,1],[1,1,1]]).astype(NU.uint8)
        mask   = (NI.convolve(self.bufbw, kernel) == 1).astype(NU.uint8)
        self.bufbw = mask
        self.buf = NU.array(self.DA, copy=1)
        NU.putmask(self.buf, mask, self.LA)

    def lichenWithDeath(self):
        kernel = NU.array([[1,1,1],[1,0,1],[1,1,1]]).astype(NU.uint8)
        mask3  = (NI.convolve(self.bufbw, kernel) == 3).astype(NU.uint8)
        mask4  = (NI.convolve(self.bufbw, kernel) == 4).astype(NU.uint8)
        mask7  = (NI.convolve(self.bufbw, kernel) == 7).astype(NU.uint8)
        mask8  = (NI.convolve(self.bufbw, kernel) == 8).astype(NU.uint8)
        maskl = mask3 + mask7 + mask8
        maskd = mask4
        self.bufbw = maskl
        self.buf = NU.array(self.DA, copy=1)
        NU.putmask(self.buf, maskl, self.LA)
        NU.putmask(self.buf, maskd, self.DA)

Folkert