---
license: apache-2.0
tags:
- RyzenAI
- Image Segmentation
- Pytorch
- Vision
datasets:
- cityscape
language:
- en
Metircs:
- mIoU
---

# SemanticFPN model trained on cityscapes

SemanticFPN is a conceptually simple yet effective baseline for panoptic segmentation trained on cityscapes. The method starts with Mask R-CNN with FPN and adds to it a lightweight semantic segmentation branch for dense-pixel prediction. It was introduced in the paper [Panoptic Feature Pyramid Networks in 2019](https://arxiv.org/pdf/1901.02446.pdf) by Kirillov, Alexander, et al.

We develop a modified version that could be supported by [AMD Ryzen AI](https://ryzenai.docs.amd.com).


## Model description

SemanticFPN is a single network that unifies the tasks of instance segmentation and semantic segmentation. The network is designed by endowing Mask R-CNN, a popular instance segmentation method, with a semantic segmentation branch using a shared Feature Pyramid Network (FPN) backbone. This simple baseline not only remains effective for instance segmentation, but also yields a lightweight, top-performing method for semantic segmentation. It is a robust and accurate baseline for both tasks and can serve as a strong baseline for future research in panoptic segmentation.


## Intended uses & limitations

You can use the raw model for image segmentation. See the [model hub](https://huggingface.co/models?sort=trending&search=amd%2FSemanticFPN) to look for all available SemanticFPN models.


## How to use

### Installation

   Follow [Ryzen AI Installation](https://ryzenai.docs.amd.com/en/latest/inst.html) to prepare the environment for Ryzen AI.
   Run the following script to install pre-requisites for this model.
   ```bash
   pip install -r requirements.txt 
   ```


### Data Preparation (optional: for accuracy evaluation)

1. Download cityscapes dataset (https://www.cityscapes-dataset.com/downloads)
    - grundtruth folder: gtFine_trainvaltest.zip [241MB]
    - image folder: leftImg8bit_trainvaltest.zip [11GB]
2. Organize the dataset directory as follows:
```Plain
└── data
     └── cityscapes
          ├── leftImg8bit
          |    ├── train
          |    └── val
          └── gtFine
               ├── train
               └── val
```

### Test & Evaluation

- Code snippet from [`infer_onnx.py`](infer_onnx.py) on how to use
```python
    parser = argparse.ArgumentParser(description='SemanticFPN model')
    parser.add_argument('--onnx_path', type=str, default='FPN_int_NHWC.onnx')
    parser.add_argument('--save_path', type=str, default='./data/demo_results/senmatic_results.png')
    parser.add_argument('--input_path', type=str, default='data/cityscapes/cityscapes/leftImg8bit/test/bonn/bonn_000000_000019_leftImg8bit.png')
    parser.add_argument('--ipu', action='store_true',
                    help='use ipu')
    parser.add_argument('--provider_config', type=str, default=None,
                    help='provider config path')
    args = parser.parse_args()

    if args.ipu:
        providers = ["VitisAIExecutionProvider"]
        provider_options = [{"config_file": args.provider_config}]
    else:
        providers = ['CPUExecutionProvider']
        provider_options = None

    onnx_path = args.onnx_path
    input_img = build_img(args)
    session = onnxruntime.InferenceSession(onnx_path, providers=providers, provider_options=provider_options)
    ort_input = {session.get_inputs()[0].name: input_img.cpu().numpy()}
    ort_output = session.run(None, ort_input)[0]
    if isinstance(ort_output, (tuple, list)):
        ort_output = ort_output[0]

    output = ort_output[0].transpose(1, 2, 0)
    seg_pred = np.asarray(np.argmax(output, axis=2), dtype=np.uint8)
    color_mask = colorize_mask(seg_pred)
    color_mask.save(args.save_path)
```

 - Run inference for a single image
  ```python
  python infer_onnx.py --onnx_path FPN_int_NHWC.onnx --input_path /Path/To/Your/Image --ipu --provider_config Path/To/vaip_config.json
  ```

 - Test accuracy of the quantized model
  ```python
  python test_onnx.py --onnx_path FPN_int_NHWC.onnx --dataset citys --test-folder ./data/cityscapes --crop-size 256 --ipu --provider_config Path/To/vaip_config.json
  ```
### Performance

| model | input size | FLOPs | mIoU on Cityscapes Validation|
|-------|------------|--------------|-------|
| SemanticFPN(ResNet18)| 256x512 | 10G | 62.9% |

| model | input size | FLOPs | INT8 mIoU on Cityscapes Validation|
|-------|------------|---------------|--------------|
| SemanticFPN(ResNet18)| 256x512 | 10G | 62.5% |

```bibtex
@inproceedings{kirillov2019panoptic,
  title={Panoptic feature pyramid networks},
  author={Kirillov, Alexander and Girshick, Ross and He, Kaiming and Doll{\'a}r, Piotr},
  booktitle={Proceedings of the IEEE/CVF conference on computer vision and pattern recognition},
  pages={6399--6408},
  year={2019}
}
```