def output_normalized_bboxes(img_data):
    """Normalize bboxes to [0, 1]"""
    # Normalize the boxes (to 0 ~ 1)
    boxes = img_data['boxes'].copy()
    img_h, img_w = img_data['img_h'], img_data['img_w']
    boxes = boxes.copy()
    boxes[:, (0, 2)] /= img_w
    boxes[:, (1, 3)] /= img_h

    return boxes