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摘要: 文本檢測在自動駕駛和跨模態圖像檢索中具有極為廣泛的應用。該技術也是基于光學字符的文本識別任務中重要的前置環節。目前,復雜場景下的文本檢測仍極具挑戰性。本文對自然場景文本檢測進行綜述,回顧了針對該問題的主要技術和相關研究進展,并對研究現狀進行分析。首先對問題進行概述,分析了自然場景中文本檢測的主要特點;接著,介紹了經典的基于連通域分析、基于滑動檢測窗的自然場景文本檢測技術;在此基礎上,綜述了近年來較為常用的深度學習文本檢測技術;最后,對自然場景文本檢測未來可能的研究方向進行展望。Abstract: Text detection is widely applied in the automatic driving and cross-modal image retrieval fields. This technique is also an important pre-procedure in optical character-based text recognition tasks. At present, text detection in complex natural scenes remains a challenging topic. Because text distribution and orientation are varied in different scenes and domains, there is still room for improvement in existing computer vision-based text detection methods. To complicate matters, natural scene texts, such as those in guideposts and shop signs, always contain words in different languages. Even characters are missing from some natural scene texts. These circumstances present more difficulties for feature extraction and feature description, thereby weakening the detectability of existing computer vision and image processing methods. In this context, text detection applications in natural scenes were summarized in this paper, the classical and newly presented techniques were reviewed, and the research progress and status were analyzed. First, the definitions of natural scene text detection and associated concepts were provided based on an analysis of the main characteristics of this problem. In addition, the classic natural scene text detection technologies, such as connected component analysis-based methods and sliding detection window-based methods, were introduced comprehensively. These methods were also compared and discussed. Furthermore, common deep learning models for scene text detection of the past decade were also reviewed. We divided these models into two main categories: region proposal-based models and segmentation-based models. Accordingly, the typical detection and semantic segmentation frameworks, including Faster R-CNN, SSD, Mask R-CNN, FCN, and FCIS, were integrated in the deep learning methods reviewed in this section. Moreover, hybrid algorithms that use region proposal ideas and segmentation strategies were also analyzed. As a supplement, several end-to-end text recognition strategies that can automatically identify characters in natural scenes were elucidated. Finally, possible research directions and prospects in this field were analyzed and discussed.
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Key words:
- text detection /
- scene text /
- connected domain analysis /
- image processing /
- statistical learning /
- deep learning
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表 1 文本檢測常用數據集
Table 1. Common datasets for text detection
Dataset Presenter Type Sample size(Training/Test) Language Direction CTW THU, Tencent Scene 32285 Chinese Horizontal ICDAR2003 ICDAR Scene 2276(1110/115) English Horizontal ICDAR2011 Scene 484(229/255) English Horizontal Graph 522(420/102) English Curve ICDAR2013 Scene 463(229/233) English Horizontal Graph 551(410/141) English Multiple Video 28(13/15) English, French, Spanish Multiple MSRA-TD500 HUST Scene 500(300/200) English
ChineseMultiple COCO-Text Microsoft Scene 63686 English Multiple RCTW-17 HUST Scene 12263(8034/4229) Chinese Horizontal English MLT2017 ICDAR Scene 18000(7200/10800) Multi-lingual Horizontal MLT2019 ICDAR Scene 20000(10000/10000) Multi-lingual Horizontal Total-Text UM Scene 1525(1225/300) English Multiple SCUT-CTW1500 SCUT Scene 1500(1000/500) Multi-lingual Multiple ArT UM, SCUT, Baidu Scene 10166(5603/4563) English Multiple Chinese www.77susu.com -
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