Depending on your need, Unstructured provides OCR-based and Transformer-based models to detect elements in the documents. The models are useful to detect the complex layout in the documents and predict the element types.

Basic usage:

elements = partition(filename=filename,


  • To use any model with the partition, set the strategy to hi_res as shown above.

  • To maintain the consistency between the unstructured and unstructured-api libraries, we are deprecating the model_name parameter. Please use hi_res_model_name parameter when specifing a model.

List of Available Models in the Partitions:

  • detectron2_onnx is a Computer Vision model by Facebook AI that provides object detection and segmentation algorithms with ONNX Runtime. It is the fastest model with the hi_res strategy.

  • yolox is a single-stage real-time object detector that modifies YOLOv3 with a DarkNet53 backbone.

  • yolox_quantized: runs faster than YoloX and its speed is closer to Detectron2.

  • chipper (beta version): the Chipper model is Unstructured’s in-house image-to-text model based on transformer-based Visual Document Understanding (VDU) models.

Using a Non-Default Model

Unstructured will download the model specified in UNSTRUCTURED_HI_RES_MODEL_NAME environment variable. If not defined, it will download the default model.

There are three ways you can use the non-default model as follows:

  1. Store the model name in the environment variable

import os
from unstructured.partition.pdf import partition_pdf

os.environ["UNSTRUCTURED_HI_RES_MODEL_NAME"] = "yolox"

out_yolox = partition_pdf("example-docs/layout-parser-paper-fast.pdf", strategy="hi_res")
  1. Pass the model name in the partition function.

filename = "example-docs/layout-parser-paper-fast.pdf"

elements = partition(filename=filename,
  1. Use unstructured-inference library.

from unstructured_inference.models.base import get_model
from unstructured_inference.inference.layout import DocumentLayout

model = get_model("yolox")
layout = DocumentLayout.from_file("sample-docs/layout-parser-paper.pdf", detection_model=model)

Bring Your Own Models

Utilizing Layout Detection Model Zoo

In the LayoutParser library, you can use various pre-trained models available in the model zoo for document layout analysis. Here’s a guide on leveraging this feature using the UnstructuredDetectronModel class in unstructured-inference library.

The UnstructuredDetectronModel class in unstructured_inference.models.detectron2 uses the faster_rcnn_R_50_FPN_3x model pretrained on DocLayNet. But any model in the model zoo can be used by using different construction parameters. UnstructuredDetectronModel is a light wrapper around the LayoutParser’s Detectron2LayoutModel object, and accepts the same arguments.

Using Your Own Object Detection Model

To seamlessly integrate your custom detection and extraction models into unstructured_inference pipeline, start by wrapping your model within the UnstructuredObjectDetectionModel class. This class acts as an intermediary between your detection model and Unstructured workflow.

Ensure your UnstructuredObjectDetectionModel subclass incorporates two vital methods:

  1. The predict method, which should be designed to accept a PIL.Image.Image type and return a list of LayoutElements, facilitating the communication of your model’s results.

  2. The initialize method is essential for loading and prepping your model for inference, guaranteeing its readiness for any incoming tasks.

It’s important that your model’s outputs, specifically from the predict method, integrate smoothly with the DocumentLayout class for optimal performance.