How to specify a custom output size in cv2.pyrDown() or cv2.pyrUp() method

edit

I want to explicitly specify the output size of the image when applying cv2.pyrDown() on images.

def gaussian_pyramid(image, scale=1.5, minSize=(30, 30)):
    yield image
    while True:
        w = int(image.shape[1] / scale)
        h = int(image.shape[0] / scale)
        image = cv2.pyrDown(image, dstsize=(w, h))
        if image.shape[0] < minSize[1] or image.shape[1] < minSize[0]:
            break
        yield image

But it is throwing an error something similar to this.

OpenCV Error: Assertion failed (ssize.width > 0 && ssize.height > 0 && std::abs(dsize.width*2 - ssize.width) <= 2 && std::abs(dsize.height*2 - ssize.height) <= 2) in pyrDown_, file /io/opencv/modules/imgproc/src/pyramids.cpp, line 873

Any idea how to specify the output size of the image as a method argument?