litert-community/resnet50

ResNet 50

The ResNet-50 architecture is a convolutional neural network pre-trained on the ImageNet-1k dataset. Originally introduced by He et al. in the landmark paper, Deep Residual Learning for Image Recognition, this model utilizes residual mapping to overcome the vanishing gradient problem, enabling the training of substantially deeper networks.

Model description

The model was converted from a checkpoint from PyTorch Vision.

The original model has: acc@1 (on ImageNet-1K): 76.13% acc@5 (on ImageNet-1K): 92.862% num_params: 25,557,032

Available Model Files

File	Description	Quantization
resnet50.tflite	Floating-point LiteRT/TFLite model.	Floating-point weights and activations.
resnet50_dynamic_wi8_afp32.tflite	Dynamic weight-quantized LiteRT/TFLite model.	INT8 weights with floating-point activations.
resnet50_int8_channelwise.tflite	Static INT8 LiteRT/TFLite model.	INT8 weights and INT8 activations, with channelwise weight quantization.

Quantization Schema

resnet50_int8_channelwise.tflite was quantized with AI Edge Quantizer's static W8A8 recipe (STATIC_WI8_AI8).

The schema is:

Tensor group	Quantization
Weights	INT8, symmetric, channelwise quantization.
Activations	INT8, asymmetric, tensorwise quantization.
Model input	INT8, tensorwise quantized NCHW image tensor with shape [1, 3, 224, 224].
Model output	INT8, tensorwise quantized logits tensor with shape [1, 1000].

Calibration used real ImageNet validation images with the TorchVision ResNet preprocessing flow. When using APIs that expose raw tensor buffers, prepare the input and output using the quantization parameters stored in the model.

Runtime Compatibility

These artifacts are intended for LiteRT CPU and GPU execution. The static INT8 channelwise artifact is also suitable for Qualcomm NPU deployment through the LiteRT Qualcomm compiler plugin and QNN AOT compilation on compatible Qualcomm devices.

MediaTek NPU enablement for the static INT8 channelwise artifact is still under validation, so this repository does not mark that artifact as MediaTek-NPU-ready yet. Use LiteRT CPU/GPU or a compatible Qualcomm NPU path for that file today.

Intended uses & limitations

The model files were converted from pretrained weights from PyTorch Vision. The models may have their own licenses or terms and conditions derived from PyTorch Vision and the dataset used for training. It is your responsibility to determine whether you have permission to use the models for your use case.

How to Use

​​1. Install Dependencies Ensure your Python environment is set up with the required libraries. Run the following command in your terminal:

pip install numpy Pillow huggingface_hub ai-edge-litert

2. Prepare Your Image The script expects an image file to analyze. Make sure you have an image (e.g., cat.jpg or car.png) saved in the same working directory as your script.

3. Save the Script Create a new file named classify.py, paste the script below into it, and save the file:

#!/usr/bin/env python3
import argparse, json
import numpy as np
from PIL import Image
from huggingface_hub import hf_hub_download
from ai_edge_litert.compiled_model import CompiledModel

def preprocess(img: Image.Image) -> np.ndarray:
   img = img.convert("RGB")
   w, h = img.size
   s = 256
   if w < h:
       img = img.resize((s, int(round(h * s / w))), Image.BILINEAR)
   else:
       img = img.resize((int(round(w * s / h)), s), Image.BILINEAR)
   left = (img.size[0] - 224) // 2
   top = (img.size[1] - 224) // 2
   img = img.crop((left, top, left + 224, top + 224))

   x = np.asarray(img, dtype=np.float32) / 255.0
   x = (x - np.array([0.485, 0.456, 0.406], dtype=np.float32)) / np.array(
       [0.229, 0.224, 0.225], dtype=np.float32
   )
   return np.transpose(x, (2, 0, 1))

def main():
   ap = argparse.ArgumentParser()
   ap.add_argument("--image", required=True)
   args = ap.parse_args()

   model_path = hf_hub_download("litert-community/resnet50", "resnet50.tflite")
   labels_path = hf_hub_download(
       "huggingface/label-files", "imagenet-1k-id2label.json", repo_type="dataset"
   )
   with open(labels_path, "r", encoding="utf-8") as f:
       id2label = {int(k): v for k, v in json.load(f).items()}

   img = Image.open(args.image)
   x = preprocess(img)

   model = CompiledModel.from_file(model_path)
   inp = model.create_input_buffers(0)
   out = model.create_output_buffers(0)

   inp[0].write(x)
   model.run_by_index(0, inp, out)

   req = model.get_output_buffer_requirements(0, 0)
   y = out[0].read(req["buffer_size"] // np.dtype(np.float32).itemsize, np.float32)

   pred = int(np.argmax(y))
   label = id2label.get(pred, f"class_{pred}")

   print(f"Top-1 class index: {pred}")
   print(f"Top-1 label: {label}")
if __name__ == "__main__":
   main()

4. Execute the Python Script Run the below command:

python classify.py --image cat.jpg

BibTeX entry and citation info

@inproceedings{he2016deep,
title={Deep residual learning for image recognition},
author={He, Kaiming and Zhang, Xiangyu and Ren, Shaoqing and Sun, Jian},
booktitle={Proceedings of the IEEE conference on computer vision and pattern recognition}, pages={770--778},
year={2016}
}