Is try-except slow?

[ssecorp]

or why does this take so god damn long time?
and if I run into an IndexError it break out of the inner loop right?
so having range up to 10000000 or 1000 wouldn't matter if biggest
working x is 800?

def getPixels(fileName):
    im = PIL.Image.open(fileName)
    colors = []
    for y in range(1, 1000):
        row = []
        for x in range(1, 1000):
            try:
                color = im.getpixel((x,y))
                row.append(color)
            except IndexError:
                break
            colors.append(row)
    return numpy.array(colors)