Wei Yu Chen

Wei Yu Chen, Ying Dai

To address the limitations of existing open-vocabulary object recognition methods, specifically high system complexity, substantial training costs, and limited generalization, this paper proposes a novel Open-Vocabulary Object Recognition (OVOR) framework based on a streamlined two-stage strategy: object segmentation followed by recognition. The framework eliminates the need for complex retraining and labor-intensive annotation. After cropping object regions, we generate object-level image embeddings alongside category-level text embeddings using CLIP, which facilitates arbitrary vocabularies. To reduce reliance on CLIP and enhance encoding flexibility, we further introduce a CNN/MLP-based method that extracts convolutional neural network (CNN) feature maps and utilizes a multilayer perceptron (MLP) to align visual features with text embeddings. These embeddings are concatenated and processed via Singular Value Decomposition (SVD) to construct a shared representation space. Finally, recognition is performed through embedding similarity matching. Experiments on COCO, Pascal VOC, and ADE20K demonstrate that training-free, CLIP-based encoding without SVD achieves the highest average AP, outperforming current state-of-the-art methods. Simultaneously, the results highlight the potential of CNN/MLP-based image encoding for OVOR.

Ying Dai, Wei Yu Chen

This paper presents a novel training-free framework for open-vocabulary image segmentation and object recognition (OVSR), which leverages EfficientNetB0, a convolutional neural network, for unsupervised segmentation and CLIP, a vision-language model, for open-vocabulary object recognition. The proposed framework adopts a two stage pipeline: unsupervised image segmentation followed by segment-level recognition via vision-language alignment. In the first stage, pixel-wise features extracted from EfficientNetB0 are decomposed using singular value decomposition to obtain latent representations, which are then clustered using hierarchical clustering to segment semantically meaningful regions. The number of clusters is adaptively determined by the distribution of singular values. In the second stage, the segmented regions are localized and encoded into image embeddings using the Vision Transformer backbone of CLIP. Text embeddings are precomputed using CLIP's text encoder from category-specific prompts, including a generic something else prompt to support open set recognition. The image and text embeddings are concatenated and projected into a shared latent feature space via SVD to enhance cross-modal alignment. Recognition is performed by computing the softmax over the similarities between the projected image and text embeddings. The proposed method is evaluated on standard benchmarks, including COCO, ADE20K, and PASCAL VOC, achieving state-of-the-art performance in terms of Hungarian mIoU, precision, recall, and F1-score. These results demonstrate the effectiveness, flexibility, and generalizability of the proposed framework.