weave_noise.py

def add_grain(im, depth=14):
    width, height = im.size
    image = scipy.misc.fromimage(im)

    code = '''
        #include <stdlib.h>
        int x, y, i;
        int depth2 = depth * 2;
        for(i = 0; i < width * height * 3; i ++) {
            int x = image[i];
            x += rand() % depth2 - depth;
            x = x > 255 ? 255 : (x < 0 ? 0 : x);
            image[i] = x;
        }
    '''
    scipy.weave.inline(code, ['depth', 'width', 'height', 'image'])
    im = scipy.misc.toimage(image)
    return im