image_convolution.py 文件源码

def convolve2d(image, kernel):
    # This function which takes an image and a kernel
    # and returns the convolution of them
    # Args:
    #   image: a numpy array of size [image_height, image_width].
    #   kernel: a numpy array of size [kernel_height, kernel_width].
    # Returns:
    #   a numpy array of size [image_height, image_width] (convolution output).

    kernel = np.flipud(np.fliplr(kernel))  # Flip the kernel
    output = np.zeros_like(image)  # convolution output
    # Add zero padding to the input image
    image_padded = np.zeros((image.shape[0] + 2, image.shape[1] + 2))
    image_padded[1:-1, 1:-1] = image
    for x in range(image.shape[1]):  # Loop over every pixel of the image
        for y in range(image.shape[0]):
            # element-wise multiplication of the kernel and the image
            output[y, x] = (kernel * image_padded[y:y + 3, x:x + 3]).sum()
    return output


# Convolve a sharpen kernel with an image