Object detection, the task of locating and identifying objects within an image, is a fundamental problem in computer vision. Traditional object detection models operated in a closed-set manner, where they were trained to recognize only a predefined set of object categories. However, the real world is open-ended and constantly evolving, necessitating a shift towards open-set object detection approaches. T-Rex2, introduced by Jiang et al., is a groundbreaking model that tackles open-set object detection by leveraging the synergy between text and visual prompts. This innovative approach enables T-Rex2 to recognize a wide array of objects, from everyday items to rare and novel ones, without the need for extensive task-specific training or fine-tuning.

Important links:

Model overview

T-Rex2 overview

T-Rex2, a promptable and interactive model for open-set object detection

T-Rex2 consists of four main components:

a) Image encoder: Extracts multi-scale feature maps from the input image using a backbone network (e.g., Swin Transformer) and refines them using deformable self-attention.

b) Visual prompt encoder: Transforms user-specified visual prompts (boxes or points) into embeddings using deformable cross-attention on the image features.

c) Text prompt encoder: Encodes category names or short phrases into embeddings using the CLIP text encoder.

d) Box decoder: Predicts bounding boxes and class labels based on the prompt embeddings and image features, following the DETR architecture.

The key innovation of T-Rex2 lies in its ability to synergize text and visual prompts through contrastive alignment. This alignment process allows the model to learn from both modalities simultaneously, enabling visual prompts to gain general knowledge from associated text prompts, while text prompts are refined and enhanced by exposure to diverse visual examples.

t-rex2 model overview

Overview of the T-Rex2 model. T-Rex2 mainly follows the design principles of DETR which is an end-to-end object detection model. Visual prompt and text prompt are introduced through deformable cross attention and CLIP text encoder, respectively, and are aligned through contrastive learning.


Versatility T-Rex2 supports four distinct workflows, catering to a wide range of application scenarios:

  • Interactive visual prompt: Users can specify objects of interest by drawing boxes or points on the image, and the model will detect and highlight those objects. This interactive process allows for real-time refinement of detection results based on user feedback.
  • Generic visual prompt: Users can provide multiple example images of a specific object, and T-Rex2 will generate a generic visual embedding that can be used to detect that object in new images. This workflow is particularly useful for detecting rare or novel objects that may not have sufficient labeled data for traditional training.
  • Text prompt: Users can input descriptive text (e.g., object names or phrases) to perform open-vocabulary object detection. This workflow leverages the power of language to guide the detection process, enabling the model to recognize objects based on their semantic descriptions.
  • Mixed prompt: T-Rex2 can utilize both text and visual prompts simultaneously for inference. The text prompts provide broad contextual understanding, while the visual prompts add precision and concrete visual cues, resulting in enhanced detection performance.
t-rex2 playground

T-Rex2 playground


t-rex2 performance

Long-tailed curve of object frequency and the number of categories that can be detected.

T-Rex2 demonstrates remarkable zero-shot object detection capabilities across four challenging benchmarks: COCO, LVIS, ODinW, and Roboflow100. Zero-shot refers to the model’s ability to detect objects it has never seen during training, showcasing its generalization prowess. On the COCO dataset, which consists of 80 common object categories, the text prompt outperforms the visual prompt by 7 AP (Average Precision) points when using the Swin-T backbone.

However, on the long-tailed LVIS dataset with 1203 categories, the visual prompt excels at detecting rare objects, surpassing the text prompt by 3.4 AP points on the rare category subset.

T-Rex2’s visual prompt truly shines on the ODinW and Roboflow100 datasets, which feature a wide variety of rare and novel objects. On these benchmarks, the visual prompt achieves significant improvements of 5.6 and 9.2 AP points, respectively, over the text prompt.

These results highlight the complementary strengths of text and visual prompts. Text prompts excel at capturing common and well-defined object categories, while visual prompts are more robust in handling rare, novel, or visually complex objects.

Real-world applications

T-Rex2’s versatility and strong performance make it a valuable tool for a wide range of real-world applications, including:

  • Agriculture and livestock monitoring: Detecting and tracking crops, plants, and animals for precision agriculture and livestock management.
  • Industrial inspection: Identifying defects, anomalies, or specific components in manufacturing processes for quality control and automation.
  • Medical imaging: Locating and classifying anatomical structures, lesions, or abnormalities in medical images for diagnosis and treatment planning.
  • Retail and logistics: Recognizing and tracking products, packages, and assets in retail stores and supply chain operations for inventory management and optimization.
  • Optical character recognition (OCR): Detecting and extracting text from images for document digitization, information retrieval, and language translation.
  • Video analysis: Extending T-Rex2’s capabilities to video object detection and tracking for applications such as surveillance, autonomous vehicles, and sports analytics.

Open-source and accessibility

To foster widespread adoption and further research, the authors have made the T-Rex2 codebase publicly available on GitHub. This open-source release includes the model architecture, training scripts, and pre-trained weights, enabling researchers and developers to easily integrate T-Rex2 into their own projects.

Furthermore, an online demo and API are provided, allowing users to interactively experiment with T-Rex2’s capabilities without the need for local setup or computational resources. This accessibility lowers the barrier to entry and encourages exploration of novel use cases and applications.

Future directions

T-Rex2 represents a significant milestone in the quest for generic object detection, but there is still room for further advancements. Some potential future directions include:

  • Improving the alignment between text and visual prompts to minimize interference and maximize synergistic benefits.
  • Developing methods to enable effective visual prompting with fewer examples, reducing the reliance on extensive visual diversity for robust detection.
  • Extending T-Rex2 to handle more complex visual understanding tasks, such as instance segmentation, keypoint detection, and visual question answering.
  • Exploring the integration of T-Rex2 with other modalities, such as audio or radar data, for multi-modal object detection in challenging environments.
  • Investigating the potential of T-Rex2 as a building block for more advanced AI systems that can understand and interact with the world in more human-like ways.


T-Rex2 represents a significant leap forward in open-set object detection, leveraging the synergy between text and visual prompts to achieve impressive zero-shot performance across diverse domains.

By combining the strengths of language and vision, T-Rex2 offers a flexible and powerful tool for tackling real-world object detection challenges. The open-source release and accessible demo of T-Rex2 pave the way for widespread adoption and innovation in various fields, from agriculture and medicine to retail and robotics.

As researchers and practitioners build upon this groundbreaking work, we can expect to see a proliferation of intelligent systems capable of understanding and interacting with the world in increasingly sophisticated ways.

Last Update: 28/03/2024