deepdream.py 文件源码

def calc_grad_tiled(img, t_grad, tile_size=512):
    '''Compute the value of tensor t_grad over the image in a tiled way.
    Random shifts are applied to the image to blur tile boundaries over 
    multiple iterations.'''
    # Pick a subregion square size
    sz = tile_size
    # Get the image height and width
    h, w = img.shape[:2]
    # Get a random shift amount in the x and y direction
    sx, sy = np.random.randint(sz, size=2)
    # Randomly shift the image (roll image) in the x and y directions
    img_shift = np.roll(np.roll(img, sx, 1), sy, 0)
    # Initialize the while image gradient as zeros
    grad = np.zeros_like(img)
    # Now we loop through all the sub-tiles in the image
    for y in range(0, max(h-sz//2, sz),sz):
        for x in range(0, max(w-sz//2, sz),sz):
            # Select the sub image tile
            sub = img_shift[y:y+sz,x:x+sz]
            # Calculate the gradient for the tile
            g = sess.run(t_grad, {t_input:sub})
            # Apply the gradient of the tile to the whole image gradient
            grad[y:y+sz,x:x+sz] = g
    # Return the gradient, undoing the roll operation
    return np.roll(np.roll(grad, -sx, 1), -sy, 0)