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Table Cell Detection Module Usage Tutorial

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Table Cell Detection Module Usage Tutorial

1. Overview

The Table Cell Detection Module is a key component of the table recognition task, responsible for locating and marking each cell region in table images. The performance of this module directly affects the accuracy and efficiency of the entire table recognition process. The Table Cell Detection Module typically outputs bounding boxes for each cell region, which are then passed as input to the table recognition pipeline for further processing.

2. Supported Model List

The inference time only includes the model inference time and does not include the time for pre- or post-processing. The "Regular Mode" values correspond to the local <code>paddle_static</code> inference engine.

<table> <tr> <th>Model</th><th>Model Download Link</th> <th>mAP(%)</th> <th>GPU Inference Time (ms) [Regular Mode / High-Performance Mode]</th> <th>CPU Inference Time (ms) [Regular Mode / High-Performance Mode]</th> <th>Model Storage Size (MB)</th> <th>Description</th> </tr> <tr> <td>RT-DETR-L_wired_table_cell_det</td> <td><a href="https://paddle-model-ecology.bj.bcebos.com/paddlex/official_inference_model/paddle3.0.0/RT-DETR-L_wired_table_cell_det_infer.tar">Inference Model</a>/<a href="https://paddle-model-ecology.bj.bcebos.com/paddlex/official_pretrained_model/RT-DETR-L_wired_table_cell_det_pretrained.pdparams">Training Model</a></td> <td rowspan="2">82.7</td> <td rowspan="2">33.47 / 27.02</td> <td rowspan="2">402.55 / 256.56</td> <td rowspan="2">124</td> <td rowspan="2">RT-DETR is a real-time end-to-end object detection model. The Baidu PaddlePaddle Vision team pre-trained on a self-built table cell detection dataset based on the RT-DETR-L as the base model, achieving good performance in detecting both wired and wireless table cells.</td> </tr> <tr> <td>RT-DETR-L_wireless_table_cell_det</td> <td><a href="https://paddle-model-ecology.bj.bcebos.com/paddlex/official_inference_model/paddle3.0.0/RT-DETR-L_wireless_table_cell_det_infer.tar">Inference Model</a>/<a href="https://paddle-model-ecology.bj.bcebos.com/paddlex/official_pretrained_model/RT-DETR-L_wireless_table_cell_det_pretrained.pdparams">Training Model</a></td> </tr> </table>

<strong>Test Environment Description:</strong>

<ul> <li><b>Performance Test Environment</b> <ul> <li><strong>Test Dataset:</strong> Internal evaluation set built by PaddleX.</li> <li><strong>Hardware Configuration:</strong> <ul> <li>GPU: NVIDIA Tesla T4</li> <li>CPU: Intel Xeon Gold 6271C @ 2.60GHz</li> </ul> </li> <li><strong>Software Environment:</strong> <ul> <li>Ubuntu 20.04 / CUDA 11.8 / cuDNN 8.9 / TensorRT 8.6.1.6</li> <li>paddlepaddle-gpu 3.0.0 / paddleocr 3.0.3</li> </ul> </li> </ul> </li> <li><b>Inference Mode Explanation</b></li> </ul> <table border="1"> <thead> <tr> <th>Mode</th> <th>GPU Configuration</th> <th>CPU Configuration</th> <th>Acceleration Technology Combination</th> </tr> </thead> <tbody> <tr> <td>Regular Mode</td> <td>FP32 Precision / No TRT Acceleration</td> <td>FP32 Precision / 8 Threads</td> <td>PaddleInference</td> </tr> <tr> <td>High-Performance Mode</td> <td>Optimal combination of prior precision type and acceleration strategy</td> <td>FP32 Precision / 8 Threads</td> <td>Choose the optimal prior backend (Paddle/OpenVINO/TRT, etc.)</td> </tr> </tbody> </table>

3. Quick Start

❗ Before starting quickly, please first install the PaddleOCR wheel package. For details, please refer to the installation tutorial.

You can quickly experience it with one command:

bash
paddleocr table_cells_detection -i https://paddle-model-ecology.bj.bcebos.com/paddlex/imgs/demo_image/table_recognition.jpg

The example above uses the <code>paddle_static</code> inference engine by default. To run it, first install PaddlePaddle by following PaddlePaddle Framework Installation.

If you choose transformers as the inference engine, make sure the Transformers environment is configured, and then run the following command:

bash
# Use the transformers engine for inference
paddleocr table_cells_detection -i https://paddle-model-ecology.bj.bcebos.com/paddlex/imgs/demo_image/table_recognition.jpg \
    --engine transformers

In most scenarios, the default paddle_static inference engine delivers better inference performance and is the recommended first choice.

<b>Note: </b>The official models would be download from HuggingFace by default. If can't access to HuggingFace, please set the environment variable PADDLE_PDX_MODEL_SOURCE="BOS" to change the model source to BOS. In the future, more model sources will be supported.

You can also integrate model inference from the table cell detection module into your project. Before running the following code, please download the sample image locally.

python
from paddleocr import TableCellsDetection
model = TableCellsDetection(model_name="RT-DETR-L_wired_table_cell_det")
output = model.predict("table_recognition.jpg", threshold=0.3, batch_size=1)
for res in output:
    res.print(json_format=False)
    res.save_to_img("./output/")
    res.save_to_json("./output/res.json")

The example above uses the <code>paddle_static</code> inference engine by default. To run it, first install PaddlePaddle by following PaddlePaddle Framework Installation.

If you choose transformers as the inference engine, make sure the Transformers environment is configured, and then run the following code:

python
from paddleocr import TableCellsDetection
model = TableCellsDetection(
    model_name="RT-DETR-L_wired_table_cell_det",
    engine="transformers",
)
output = model.predict("table_recognition.jpg", threshold=0.3, batch_size=1)
for res in output:
    res.print(json_format=False)
    res.save_to_img("./output/")
    res.save_to_json("./output/res.json")

In most scenarios, the default paddle_static inference engine delivers better inference performance and is the recommended first choice.

If you want to use the trained model with the paddle_dynamic or transformers engine, refer to the Weight Conversion section in the Inference Engine section below to convert the model from the pdparams format to the safetensors format using PaddleX.

After running, the result obtained is:

{'res': {'input_path': 'table_recognition.jpg', 'page_index': None, 'boxes': [{'cls_id': 0, 'label': 'cell', 'score': 0.9698355197906494, 'coordinate': [2.3011515, 0, 546.29926, 30.530712]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9690820574760437, 'coordinate': [212.37508, 64.62493, 403.58868, 95.61413]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9668057560920715, 'coordinate': [212.46791, 30.311079, 403.7182, 64.62613]}, {'cls_id': 0, 'label': 'cell', 'score': 0.966505229473114, 'coordinate': [403.56082, 64.62544, 546.83215, 95.66117]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9662341475486755, 'coordinate': [109.48873, 64.66485, 212.5177, 95.631294]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9654079079627991, 'coordinate': [212.39197, 95.63037, 403.60852, 126.78792]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9653300642967224, 'coordinate': [2.2320926, 64.62229, 109.600494, 95.59732]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9639787673950195, 'coordinate': [403.5752, 30.562355, 546.98975, 64.61531]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9636150002479553, 'coordinate': [2.1537683, 30.410172, 109.568306, 64.62762]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9631900191307068, 'coordinate': [2.0534437, 95.57448, 109.57601, 126.71458]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9631181359291077, 'coordinate': [403.65976, 95.68139, 546.84766, 126.713394]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9614537358283997, 'coordinate': [109.56504, 30.391184, 212.65425, 64.6444]}, {'cls_id': 0, 'label': 'cell', 'score': 0.9607433080673218, 'coordinate': [109.525795, 95.62622, 212.44917, 126.8258]}]}}

The parameter meanings are as follows:

<ul> <li><code>input_path</code>: Path of the input image to be predicted</li> <li><code>page_index</code>: If the input is a PDF file, it indicates which page of the PDF it is; otherwise, it is `None`</li> <li><code>boxes</code>: Predicted bounding box information, a list of dictionaries. Each dictionary represents a detected object and contains the following information: <ol start = "1" type ="1"> <li><code>cls_id</code>: Class ID, an integer</li> <li><code>label</code>: Class label, a string</li> <li><code>score</code>: Confidence of the bounding box, a float</li> <li><code>coordinate</code>: Coordinates of the bounding box, a list of floats in the format <code>[xmin, ymin, xmax, ymax]</code></li> </ol> </li> </ul> The visualized image is as follows:

The relevant methods, parameters, etc., are described as follows:

  • <code>TableCellsDetection</code> instantiates the table cell detection model (taking <code>RT-DETR-L_wired_table_cell_det</code> as an example here), with specific explanations as follows:
<table> <thead> <tr> <th>Parameter</th> <th>Description</th> <th>Type</th> <th>Default</th> </tr> </thead> <tbody> <tr> <td><code>model_name</code></td> <td><b>Meaning:</b> Model name.

<b>Description:</b> If set to <code>None</code>, <code>RT-DETR-L_wired_table_cell_det</code> will be used.</td>

<td><code>str|None</code></td> <td><code>None</code></td> </tr> <tr> <td><code>model_dir</code></td> <td><b>Meaning:</b>Model storage path.</td> <td><code>str|None</code></td> <td><code>None</code></td> </tr> <tr> <td><code>device</code></td> <td><b>Meaning:</b>Device for inference.

<b>Description:</b> <b>For example:</b> <code>"cpu"</code>, <code>"gpu"</code>, <code>"npu"</code>, <code>"gpu:0"</code>, <code>"gpu:0,1"</code>.

If multiple devices are specified, parallel inference will be performed.

By default, GPU 0 is used if available; otherwise, CPU is used.</td>

<td><code>str|None</code></td> <td><code>None</code></td> </tr> <tr> <td><code>engine</code></td> <td><b>Meaning:</b> Inference engine. <b>Description:</b> Supports <code>None</code> (the default), <code>paddle</code>, <code>paddle_static</code>, <code>paddle_dynamic</code>, and <code>transformers</code>. When left as <code>None</code>, local inference uses the <code>paddle_static</code> engine by default. For detailed descriptions, supported values, compatibility rules, and examples, see <a href="../inference_engine.en.md">Inference Engine and Configuration</a>.</td> <td><code>str|None</code></td> <td><code>None</code></td> </tr> <tr> <td><code>engine_config</code></td> <td><b>Meaning:</b> Inference-engine configuration. <b>Description:</b> Recommended together with <code>engine</code>. For supported fields, compatibility rules, and examples, see <a href="../inference_engine.en.md">Inference Engine and Configuration</a>.</td> <td><code>dict|None</code></td> <td><code>None</code></td> </tr> <tr> <td><code>enable_hpi</code></td> <td><b>Meaning:</b>Whether to enable high-performance inference.</td> <td><code>bool</code></td> <td><code>False</code></td> </tr> <tr> <td><code>use_tensorrt</code></td> <td><b>Meaning:</b>Whether to use the Paddle Inference TensorRT subgraph engine.

<b>Description:</b> If the model does not support acceleration through TensorRT, setting this flag will not enable acceleration.

For Paddle with CUDA version 11.8, the compatible TensorRT version is 8.x (x>=6), and it is recommended to install TensorRT 8.6.1.6.

</td> <td><code>bool</code></td> <td><code>False</code></td> </tr> <tr> <td><code>precision</code></td> <td><b>Meaning:</b>Computation precision when using the Paddle Inference TensorRT subgraph engine.

<b>Description:</b> <b>Options:</b> <code>"fp32"</code>, <code>"fp16"</code>.</td>

<td><code>str</code></td> <td><code>"fp32"</code></td> </tr> <tr> <td><code>enable_mkldnn</code></td> <td><b>Meaning:</b>Whether to enable MKL-DNN acceleration for inference.

<b>Description:</b> If MKL-DNN is unavailable or the model does not support it, acceleration will not be used even if this flag is set.</td>

<td><code>bool</code></td> <td><code>True</code></td> </tr> <tr> <td><code>mkldnn_cache_capacity</code></td> <td><b>Meaning:</b>MKL-DNN cache capacity.</td> <td><code>int</code></td> <td><code>10</code></td> </tr> <tr> <td><code>cpu_threads</code></td> <td><b>Meaning:</b>Number of threads to use for inference on CPUs.</td> <td><code>int</code></td> <td><code>10</code></td> </tr> <tr> <td><code>img_size</code></td> <td><b>Meaning:</b>Input image size.

<b>Description:</b>

<ul><li><b>int</b>: e.g. <code>640</code>, resizes input image to 640x640</li><li><b>list</b>: e.g. <code>[640, 512]</code>, resizes input image to 640 width and 512 height</li></ul></td> <td><code>int|list|None</code></td> <td>None</td> </tr> <tr> <td><code>threshold</code></td> <td><b>Meaning:</b>Threshold for filtering out low-confidence prediction results.

<b>Description:</b>

<ul><li><b>float</b>: e.g. <code>0.2</code>, filters out all boxes with confidence below 0.2.</li><li><b>dict</b>: keys are <code>int</code> (class id), values are <code>float</code> thresholds, e.g. <code>{0: 0.45, 2: 0.48, 7: 0.4}</code>, applies thresholds to specific classes.</li><li><b>None</b>: uses the model's default configuration.</li></ul></td> <td><code>float|dict|None</code></td> <td><code>None</code></td> </tr> </tbody> </table>
  • Call the <code>predict()</code> method of the table cell detection model for inference prediction. This method will return a result list. Additionally, this module also provides a <code>predict_iter()</code> method. Both methods are consistent in terms of parameter acceptance and result return. The difference is that <code>predict_iter()</code> returns a <code>generator</code>, which can process and obtain prediction results step by step, suitable for handling large datasets or scenarios where memory saving is desired. You can choose to use either of these methods according to your actual needs. The <code>predict()</code> method has parameters <code>input</code>, <code>batch_size</code>, and <code>threshold</code>, with specific explanations as follows:
<table> <thead> <tr> <th>Parameter</th> <th>Description</th> <th>Type</th> <th>Default</th> </tr> </thead> <tr> <td><code>input</code></td> <td> <b>Meaning:</b>Input data to be predicted. Required.

<b>Description:</b> Supports multiple input types:

<ul> <li><b>Python Var</b>: e.g., <code>numpy.ndarray</code> representing image data</li> <li><b>str</b>: Local image file or PDF file path: <code>/root/data/img.jpg</code>; <b>URL</b>: Image or PDF file network URL: <a href="https://paddle-model-ecology.bj.bcebos.com/paddlex/imgs/demo_image/img_rot180_demo.jpg">Example</a>; <b>Directory</b>: Should contain images for prediction, e.g., <code>/root/data/</code> (currently, PDF files in directories are not supported, PDF files need to be specified by file path)</li> <li><b>list</b>: List elements should be of the above types, e.g., <code>[numpy.ndarray, numpy.ndarray]</code>, <code>["/root/data/img1.jpg", "/root/data/img2.jpg"]</code>, <code>["/root/data1", "/root/data2"]</code></li> </ul> </td> <td><code>Python Var|str|list</code></td> <td></td> </tr> <tr> <td><code>batch_size</code></td> <td><b>Meaning:</b>Batch size.

<b>Description:</b> Positive integer.</td>

<td><code>int</code></td> <td>1</td> </tr> <tr> <td><code>threshold</code></td> <td><b>Meaning:</b>Same meaning as the instantiation parameters.

<b>Description:</b>If set to <code>None</code>, the instantiation value is used; otherwise, this parameter takes precedence.</td>

<td><code>float|dict|None</code></td> <td>None</td> </tr> </table>
  • Process the prediction results. The prediction result for each sample is a corresponding Result object, which supports printing, saving as an image, and saving as a <code>json</code> file:
<table> <thead> <tr> <th>Method</th> <th>Description</th> <th>Parameter</th> <th>Type</th> <th>Parameter Description</th> <th>Default Value</th> </tr> </thead> <tr> <td rowspan = "3"><code>print()</code></td> <td rowspan = "3">Print result to terminal</td> <td><code>format_json</code></td> <td><code>bool</code></td> <td>Whether to format the output content using <code>JSON</code> indentation</td> <td><code>True</code></td> </tr> <tr> <td><code>indent</code></td> <td><code>int</code></td> <td>Specifies the indentation level to beautify the output <code>JSON</code> data, making it more readable, effective only when <code>format_json</code> is <code>True</code></td> <td>4</td> </tr> <tr> <td><code>ensure_ascii</code></td> <td><code>bool</code></td> <td>Controls whether to escape non-<code>ASCII</code> characters into <code>Unicode</code>. When set to <code>True</code>, all non-<code>ASCII</code> characters will be escaped; <code>False</code> will retain the original characters, effective only when <code>format_json</code> is <code>True</code></td> <td><code>False</code></td> </tr> <tr> <td rowspan = "3"><code>save_to_json()</code></td> <td rowspan = "3">Save the result as a json format file</td> <td><code>save_path</code></td> <td><code>str</code></td> <td>The path to save the file. When specified as a directory, the saved file is named consistent with the input file type.</td> <td>None</td> </tr> <tr> <td><code>indent</code></td> <td><code>int</code></td> <td>Specifies the indentation level to beautify the output <code>JSON</code> data, making it more readable, effective only when <code>format_json</code> is <code>True</code></td> <td>4</td> </tr> <tr> <td><code>ensure_ascii</code></td> <td><code>bool</code></td> <td>Controls whether to escape non-<code>ASCII</code> characters into <code>Unicode</code>. When set to <code>True</code>, all non-<code>ASCII</code> characters will be escaped; <code>False</code> will retain the original characters, effective only when <code>format_json</code> is <code>True</code></td> <td><code>False</code></td> </tr> <tr> <td><code>save_to_img()</code></td> <td>Save the result as an image format file</td> <td><code>save_path</code></td> <td><code>str</code></td> <td>The path to save the file. When specified as a directory, the saved file is named consistent with the input file type.</td> <td>None</td> </tr> </table>
  • Additionally, the result can be obtained through attributes that provide the visualized images with results and the prediction results, as follows:
<table> <thead> <tr> <th>Attribute</th> <th>Description</th> </tr> </thead> <tr> <td rowspan = "1"><code>json</code></td> <td rowspan = "1">Get the prediction result in <code>json</code> format</td> </tr> <tr> <td rowspan = "1"><code>img</code></td> <td rowspan = "1">Get the visualized image</td> </tr> </table>

4. Secondary Development

Since PaddleOCR does not directly provide training for the table cell detection module, if you need to train a table cell detection model, you can refer to the PaddleX Table Cell Detection Module Secondary Development section for training. The trained model can be seamlessly integrated into the PaddleOCR API for inference.

If you want to use the paddle_dynamic or transformers engine with the trained model, please refer to the Weight Conversion section in Inference Engine later in this document to convert the model from the pdparams format to the safetensors format using PaddleX.

5. Inference Engine

For detailed descriptions, values, compatibility rules, and examples of the inference engine, please refer to <a href="../inference_engine.en.md">Inference Engine and Configuration Description</a>.

5.1 Speed Data

<table border="1"> <thead> <tr> <th>model</th> <th>engine</th> <th>Preprocessing (ms)</th> <th>Inference (ms)</th> <th>PostProcessing (ms)</th> <th>End-to-End (ms)</th> </tr> </thead> <tbody> <tr> <td rowspan="3">RT-DETR-L_wired_table_cell_det</td> <td>paddle_static</td> <td>3.59</td> <td>23.11</td> <td>0.14</td> <td>27.02</td> </tr> <tr> <td>paddle_dynamic</td> <td>4.04</td> <td>70.38</td> <td>0.15</td> <td>75.49</td> </tr> <tr> <td>transformers</td> <td>3.69</td> <td>37.30</td> <td>0.71</td> <td>42.10</td> </tr> <tr> <td rowspan="3">RT-DETR-L_wireless_table_cell_det</td> <td>paddle_static</td> <td>3.77</td> <td>23.44</td> <td>0.14</td> <td>27.52</td> </tr> <tr> <td>paddle_dynamic</td> <td>4.01</td> <td>69.97</td> <td>0.15</td> <td>75.10</td> </tr> <tr> <td>transformers</td> <td>3.69</td> <td>37.11</td> <td>0.71</td> <td>41.91</td> </tr> </tbody> </table>

<strong>Test Environment Description:</strong>

<ul> <li><strong>Test Data:</strong> [Sample Image](https://paddle-model-ecology.bj.bcebos.com/paddlex/imgs/demo_image/table_recognition.jpg)</li> <li><strong>Hardware Configuration:</strong> <ul> <li>GPU: NVIDIA A100 40G</li> <li>CPU: Intel(R) Xeon(R) Gold 6248 CPU @ 2.50GHz</li> </ul> </li> <li><strong>Software Environment:</strong> <ul> <li>Ubuntu 22.04 / CUDA 12.6 / cuDNN 9.5</li> <li>paddlepaddle-gpu 3.2.1 / paddleocr 3.5 / transformers 5.4.0 / torch 2.10</li> </ul> </li> </ul>

5.2 Weight Conversion

When using the inference engine, the system will automatically download the official pre-trained model. If you need to use a self-trained model with the paddle_dynamic or transformers engine, please refer to the PaddleX Table Cell Detection Module Weight Conversion section to convert the model from the pdparams format to the safetensors format using PaddleX. This allows seamless integration into the PaddleOCR API for inference.

6. FAQ