C++部署onnx模型（C++和Python3混合编程）

1. 纯python部署（onnx模型）

import os
import time

import numpy as np
import onnxruntime
import json
import cv2


def imnormalize(img, mean, std, to_rgb=True):
    """Normalize an image with mean and std.

    Args:
        img (ndarray): Image to be normalized.
        mean (ndarray): The mean to be used for normalize.
        std (ndarray): The std to be used for normalize.
        to_rgb (bool): Whether to convert to rgb.

    Returns:
        ndarray: The normalized image.
    """
    img = img.copy().astype(np.float32)

    # cv2 inplace normalization does not accept uint8
    mean = np.float64(mean.reshape(1, -1))
    stdinv = 1 / np.float64(std.reshape(1, -1))
    if to_rgb:
        cv2.cvtColor(img, cv2.COLOR_BGR2RGB, img)  # inplace
    cv2.subtract(img, mean, img)  # inplace
    cv2.multiply(img, stdinv, img)  # inplace
    return img


def letterbox_image(img, input_dim, fill_value):