3 min read

Export Yolo V7 to Tensorflow Lite

The process of converting the PyTorch model to Tensorflow Lite

PyTorch model -> ONXX model -> Tensorflow Model -> Tensorflow Lite Model

Start by creating a new virtual environment:

python3 -m venv .venv
source .venv/bin/activate

Install basic requirements:

pip install onnx onnxruntime onnxsim onnx-tf

Clone YOLO v7 repository and download official YOLO v7 PyTorch weights:

git clone https://github.com/WongKinYiu/yolov7.git
cd yolov7
wget https://github.com/WongKinYiu/yolov7/releases/download/v0.1/yolov7.pt

Run requirements.txt install within yolov7 folder to install pytorch and the rest of libraries:

pip install -r requirements.txt

PyTorch model to ONXX

Run the export script from the yolov7 folder:

python export.py --weights yolov7-tiny.pt --grid --end2end --simplify \
        --topk-all 100 --iou-thres 0.65 --conf-thres 0.35 --img-size 640 640 --max-wh 640

My output (missing onnx_graphsurgeon but it seem it didn't stop the export).

Install required tensorflow libraries

pip install tensorflow tensorflow_probability

Convert onxx model to tensorflow

mkdir tfmodel
onnx-tf convert -i yolov7.onnx -o tfmodel/

the output should be stored in the newly created folder tfmodel

Convert model from Tensorflow to Tensorflow Lite

Create a small python script and name it tf_model_to_tf_lite.py, then copy paste the contents:

import tensorflow as tf

converter = tf.lite.TFLiteConverter.from_saved_model('tfmodel/')
tflite_model = converter.convert()

with open('tfmodel/yolov7_model.tflite', 'wb') as f:

Run the script:

python3 tf_model_to_tf_lite.py

The output of the script should be Tensorflow Lite model named tfmodel/yolov7_model.tflite

Run inference

import cv2
import random
import numpy as np
import tensorflow as tf
import matplotlib.pyplot as plt

# Load the TFLite model and allocate tensors.
interpreter = tf.lite.Interpreter(model_path="tfmodel/yolov7_model.tflite")

# Name of the classes according to class indices.
names = [
    "traffic light",
    "fire hydrant",
    "stop sign",
    "parking meter",
    "sports ball",
    "baseball bat",
    "baseball glove",
    "tennis racket",
    "wine glass",
    "hot dog",
    "potted plant",
    "dining table",
    "cell phone",
    "teddy bear",
    "hair drier",

# Creating random colors for bounding box visualization.
colors = {
    name: [random.randint(0, 255) for _ in range(3)] for i, name in enumerate(names)

img = cv2.imread("data/image2.jpg")
image = cv2.resize(image, size, interpolation=cv2.INTER_LINEAR)
image = np.expand_dims(image, 0)
image = np.ascontiguousarray(image)
im = image.astype(np.float32)
im /= 255

 Allocate tensors.
# Get input and output tensors.
input_details = interpreter.get_input_details()
output_details = interpreter.get_output_details()

# Test the model on random input data.
input_shape = input_details[0]["shape"]
interpreter.set_tensor(input_details[0]["index"], im)


# The function `get_tensor()` returns a copy of the tensor data.
# Use `tensor()` in order to get a pointer to the tensor.
output_data = interpreter.get_tensor(output_details[0]["index"])

ori_images = [img.copy()]

for i, (batch_id, x0, y0, x1, y1, cls_id, score) in enumerate(output_data):
    image = ori_images[int(batch_id)]
    box = np.array([x0, y0, x1, y1])
    box -= np.array(dwdh * 2)
    box /= ratio
    box = box.round().astype(np.int32).tolist()
    cls_id = int(cls_id)
    score = round(float(score), 3)
    name = names[cls_id]
    color = colors[name]
    name += " " + str(score)
    cv2.rectangle(image, box[:2], box[2:], color, 2)
        (box[0], box[1] + 20),
        [225, 255, 255],
# plt.imshow(ori_images[0])
cv2.imshow("test", ori_images[0])

# Destroys all the windows created


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Igor Rendulic

  • Salt Lake City
Explorer, developer, ... Using this website as the bookmarking service for the things that might become useful in the future.
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