[PyQt] Pixel Manipulation Very Slow?

[zhang jian]

Hello,

This is my first post. I want to write a simply app layering several images
each with different weighting. This problem is pixel manipulation by QImage
appears to be quite slow. My code is:

        w = image.width()
        h = image.height()

        for j in range(h):
            for i in range(w):
                 col = QtGui.QColor(image.pixel(i, j))

                 col.setRed(col.red()*self.fKd)
                 image.setPixel(i, j, col.rgb());



painter.drawImage(0, 0, image)

Just one image changed in red channel. It took about 5 seconds to redraw a
1280 X 720 image any time I changed Kd. Far from interactive. I'd like to
know is there any way to do stuff like that faster? Or calculating a million
pixels in PyQt is just a bad idea? Any advice should be appreciated.

Thanks,

zhang
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