Text Region Extraction Research Articles

Handheld Mobile Device Based Text Region Extraction and Binarization of Image Embedded Text Documents

Abstract.Effective text region extraction and binarization of image embedded text documents on mobile devices having limited computational resources is an open research problem. In this paper, we present one such technique for preprocessing images captured with built-in cameras of handheld devices with an aim of developing an efficient Business Card Reader. At first, the card image is processed for isolating foreground components. These foreground components are classified as either text or non-text using different feature descriptors of texts and images. The non-text components are removed and the textual ones are binarized with a fast adaptive algorithm. Specifically, we propose new techniques (targeted to mobile devices) for (i) foreground component isolation, (ii) text extraction and (iii) binarization of text regions from camera captured business card images. Experiments with business card images of various resolutions show that the present technique yields better accuracy and involves low computational overhead in comparison with the state-of-the-art. We achieve optimum text/non-text separation performance with images of resolution 800×600 pixels with an average recall rate of 93.90% and a precision rate of 96.84%. It involves a peak memory consumption of 0.68 MB and processing time of 0.102 seconds on a moderately powerful notebook, and 4 seconds of processing time on a PDA.

Text Extraction of Colour Images using Mathematical Morphology & HAAR Transform

Digital image processing is an ever expanding and dynamic area with applications reaching out into our daily life such as digital signature, authentication, surveillance, medicine, space exploration, automated industry inspection and many others areas. Theseapplications are involved in different processes like image enhancement, object detection, features extraction, colour imaging etc. Implementation of such applications on a general purpose computer can be easier, but every time it is not efficient due to additional constraints on memory and other peripheral devices. Out of the five senses - sight, hearing, touch, smell and taste, humans use to perceive their environment. Among all,sight of images is the most powerful. More than 99% of the activity of the human brain is involved in processing images from the visual cortex. A visual image is rich in information. There is an efficient yet simple method to extract text regions from video sequences or static images. The speed of Haar discrete wavelet transform (DWT) operates the fastest among all wavelets because its coefficients are either 1 or -1. It is one of the reasons that Haar DWT is used to detect edges of candidate text regions. Image sub bands contain both text edges and non-text edges. The intensity of the text edges is also different from that of the non-text edges. Therefore, thresholdingis used to preliminary remove the non-text edges. Text regions of colour images are composed of horizontal edges, vertical edges and diagonal edges. Morphological dilation operators as AND, OR are applied to connect isolated text edges of each detail component sub-band in a transformed binary image. The simulation is carried out on MATLAB 2012 image processing tool.

English

Text detection and extraction from scene images is useful in finding certain facts in supporting court of laws for solving crime problems and various forensic science applications. Text detection from scene images is a difficult and challenging problem due to various issues such as; varying font size, style, uneven illumination and other degradations. In this paper, a new method that uses wavelet energy features for text detection and extraction from scene images is presented. Initially, preprocessed binarized image will be divided into 50x50 blocks. Then, wavelet energy features are obtained from every block and potential text blocks are identified using newly defined discriminant functions. Further, the detected text blocks are merged and refined to extract text regions. The proposed method is robust and achieves a detection rate of 97% on a variety of scene images each of size 240x320. KeywordsText detection, scene images, wavelet energy features, discriminant functions. International Journal of Machine Intelligence ISSN: 0975-2927 & E-ISSN: 0975-9166, Volume 4, Issue 1, 2012 Citation: Angadi S.A., et al. (2012) Text detection and extraction from Scene Images using wavelet features. International Journal of Machine Intelligence, ISSN: 0975-2927 & E-ISSN: 0975-9166, Volume 4, Issue 1, pp.-409. Copyright: Copyright©2012 Angadi S.A., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Toward a computer vision-based wayfinding aid for blind persons to access unfamiliar indoor environments

Independent travel is a well known challenge for blind and visually impaired persons. In this paper, we propose a proof-of-concept computer vision-based wayfinding aid for blind people to independently access unfamiliar indoor environments. In order to find different rooms (e.g. an office, a lab, or a bathroom) and other building amenities (e.g. an exit or an elevator), we incorporate object detection with text recognition. First we develop a robust and efficient algorithm to detect doors, elevators, and cabinets based on their general geometric shape, by combining edges and corners. The algorithm is general enough to handle large intra-class variations of objects with different appearances among different indoor environments, as well as small inter-class differences between different objects such as doors and door-like cabinets. Next, in order to distinguish intra-class objects (e.g. an office door from a bathroom door), we extract and recognize text information associated with the detected objects. For text recognition, we first extract text regions from signs with multiple colors and possibly complex backgrounds, and then apply character localization and topological analysis to filter out background interference. The extracted text is recognized using off-the-shelf optical character recognition (OCR) software products. The object type, orientation, location, and text information are presented to the blind traveler as speech.

Localizing Text in Scene Images by Boundary Clustering, Stroke Segmentation, and String Fragment Classification

In this paper, we propose a novel framework to extract text regions from scene images with complex backgrounds and multiple text appearances. This framework consists of three main steps: boundary clustering (BC), stroke segmentation, and string fragment classification. In BC, we propose a new bigram-color-uniformity-based method to model both text and attachment surface, and cluster edge pixels based on color pairs and spatial positions into boundary layers. Then, stroke segmentation is performed at each boundary layer by color assignment to extract character candidates. We propose two algorithms to combine the structural analysis of text stroke with color assignment and filter out background interferences. Further, we design a robust string fragment classification based on Gabor-based text features. The features are obtained from feature maps of gradient, stroke distribution, and stroke width. The proposed framework of text localization is evaluated on scene images, born-digital images, broadcast video images, and images of handheld objects captured by blind persons. Experimental results on respective datasets demonstrate that the framework outperforms state-of-the-art localization algorithms.

A Comparative Study of Segmentation in MixedMode Images

detection and extraction of text regions in an image is a well known problem in the computer vision research area. Text extraction is a critical and essential step as it sets up the quality of the final recognition result. It aims at segmenting text from background, i.e isolating text pixels from those of background. Since readymade mixed mode image data is not available, it is necessary to create our own database. The database plays an important role as segmentation is to be done in an image. In educational videos and in presentation of lectures, graphic play an important role. In television industry text and images are simultaneously transmitted. In such similar application compression of data and bandwidth play an important role. To achieve better compression and bandwidth utilization properly, an efficient segmentation technique is necessary. In this paper, we analyze mixed mode images by two methods.

Analysis and classification for complex scanned documents

Page-layout-classification methodologies aim to extract text and non-textual regions such as graphics, photos, or logos. These techniques have applications in digital document storage and retrieval where efficient memory consumption and quick retrieval are required.1 Such classification algorithms can also be used in the printing industry for selective or enhanced scanning and object-oriented rendering (printing different parts of a document with different resolution depending on the content).2 Additionally, these techniques can be used as an initial step for various applications. These include optical-character recognition (the electronic translation of handwritten or printed text into machine-encoded text) and graphic interpretation (classifying documents—into military, educational, and others—according to the image content).3 In the past two decades, several techniques have focused on identifying text regions in scanned documents.4, 5 In addition, comprehensive algorithms that aim to identify both text and graphic regions have been developed.6, 7 However, these systems are limited to specific documents, such as newsletters or articles, where the background region is assumed white.8, 9 This assumption not only excludes complex backgrounds and colored documents (such as book covers, advertisements, and flyers),10 but also limits practicality and feasibility when applied to non-ideal (complex) documents. We propose a page-layout-segmentation technique to extract text, image, and strong-edge or strong-line regions (actual lines in the document or transition pixels between a picture and text or a picture and background).11 The algorithm consists of four modules: pre-processing stage, text detection, photo detection, and strong-edge or strong-line detection units. We start by applying a pre-processing module that includes image scaling and enhancement, as well as color-space conversion Figure 1. Line detection results for two different documents. (a) Original image, (b) enhanced L* channel of the CIE L*a*b* space, and (c) final segmentation map where strong-edge or strong-line and text regions are colored in yellow and green, respectively.

Text Region Extraction in a Document Image Based on Discrete Wavelet transforms

This paper presents a new approach for extracting text region from the document images employing the discrete wavelet transform. The detection of text region is achieved by the discrete wavelet transforms. Experimental results show that the proposed method gives better text extraction from the document images.

카메라 영상 위에서의 문자 영역 추출 및 OCR

기존의 OCR 엔진은 보정된 환경에서 읽혀진 서류 영상에 맞게 설계되어있다. 스마트 폰을 비롯한 검정 화면 거리가 보정되지 않은 기기에서 읽혀진 영상에서는 삼차원 원근 투시에 의한 찌그러짐 또는 곡면상에서의 찌그러짐 등이 핵심적인 문제점들로 여겨진다. 휴대용 단말기에서 읽혀진 영상들에서의 OCR 기능에 대한 요구가 증가일로에 있는 시점에서, 본 논문에서는 문제점들을 세 가지로 구분하고 - 회전에 무관한 문자 영역 추출, 폰트 등의 크기에 무관한 문자 선 영역 추출, 3차원 매핑 이론 - 이를 해결하기위한 방법을 제시하였다. 이러한 방법론을 통합하여 카메라 영상 위에서의 OCR을 개발하였다. Traditional OCR engines are designed to the scanned documents in calibrated environment. Three dimensional perspective distortion and smooth distortion in images are critical problems caused by un-calibrated devices, e.g. image from smart phones. To meet the growing demand of character recognition of texts embedded in the photos acquired from the non-calibrated hand-held devices, we address the problem in three categorical aspects: rotational invariant method of text region extraction, scale invariant method of text line segmentation, and three dimensional perspective mapping. With the integration of the methods, we developed an OCR for camera-captured images.

Spectral Fluctuation Method: A Texture-Based Method to Extract Text Regions in General Scene Images

To obtain text information included in a scene image, we first need to extract text regions from the image before recognizing the text. In this paper, we examine human vision and propose a novel method to extract text regions by evaluating textural variation. Human beings are often attracted by textural variation in scenes, which causes foveation. We frame a hypothesis that texts also have similar property that distinguishes them from the natural background. In our method, we calculate spatial variation of texture to obtain the distribution of the degree of likelihood of text region. Here we evaluate the changes in local spatial spectrum as the textural variation. We investigate two options to evaluate the spectrum, that is, those based on one- and two-dimensional Fourier transforms. In particular, in this paper, we put emphasis on the one-dimensional transform, which functions like the Gabor filter. The proposal can be applied to a wide range of characters mainly because it employs neither templates nor heuristics concerning character size, aspect ratio, specific direction, alignment, and so on. We demonstrate that the method effectively extracts text regions contained in various general scene images. We present quantitative evaluation of the method by using databases open to the public.

Morphology-based text line extraction

This paper presents a morphology-based text line extraction algorithm for extracting text regions from cluttered images. First of all, the method defines a novel set of morphological operations for extracting important contrast regions as possible text line candidates. The contrast feature is robust to lighting changes and invariant against different image transformations like image scaling, translation, and skewing. In order to detect skewed text lines, a moment-based method is then used for estimating their orientations. According to the orientation, an x-projection technique can be applied to extract various text geometries from the text-analogue segments for text verification. However, due to noise, a text line region is often fragmented to different pieces of segments. Therefore, after the projection, a novel recovery algorithm is then proposed for recovering a complete text line from its pieces of segments. After that, a verification scheme is then proposed for verifying all extracted potential text lines according to their text geometries. Experimental results show that the proposed method improves the state-of-the-art work in terms of effectiveness and robustness for text line detection.

An Edge-based Text Region Extraction Algorithm for Indoor Mobile Robot Navigation

An Edge-based Text Region Extraction Algorithm for Indoor Mobile Robot Navigation

색상레이어를 이용한 스팸메일 영상에서의 텍스트 영역 추출

본 논문에서는 스팸메일 영상에서 텍스트 영역의 추출을 위한 색상 레이어기반의 알고리즘을 제안한다. CLTE(color layer-based text extraction)는 색상 레이어를 사용하여 영상을 8개로 나눈다. 8개 각각의 영상에서 연결요소를 추출한 후, 연결요소의 크기에 의해서 텍스트 영역과 비텍스트 영역을 분류하고 텍스트 영역을 추출한다. 또한, 추출된 텍스트 영역으로부터 회손된 획 정보를 복구하는 알고리즘을 제안한다. 이진영상내의 한글 문자에는 두 가지 형태의 손상된 획이 존재한다. 첫째 중성 획에 해당하는 'ㅣ' 나 'ㅡ' 등의 획들이 지워지는 경우와, 둘째 초 종성 획에 해당하는 'ㅁ' 이나 'ㅇ'이 흑화소로 채워지는 경우가 있다. 제안한 알고리즘은 이러한 두 가지 손상된 획들을 복구해준다. 200개의 스팸메일 영상을 사용한 실험 결과 제안한 알고리즘이 기존의 텍스트 추출 알고리즘보다 10% 이상 우수함을 관측하였다. In this paper, we propose an algorithm for extracting text regions from spam-mail images using color layer. The CLTE(color layer-based text extraction) divides the input image into eight planes as color layers. It extracts connected components on the eight images, and then classifies them into text regions and non-text regions based on the component sizes. We also propose an algorithm for recovering damaged text strokes from the extracted text image. In the binary image, there are two types of damaged strokes: (1) middle strokes such as 'ㅣ' or 'ㅡ' are deleted, and (2) the first and/or last strokes such as 'ㅇ' or 'ㅁ' are filled with black pixels. An experiment with 200 spam-mail images shows that the proposed approach is more accurate than conventional methods by over 10%.

Toward automatic video-based whiteboard reading

The increasing popularity of whiteboards as a popular tool in meeting rooms has been accompanied by a growing interest in making use of the whiteboard as a user interface for human-computer interaction. Therefore, systems based on electronic whiteboards have been developed in order to serve as meeting assistants for, e.g., collaborative working. However, as special pens and erasers are required, natural interaction is restricted. In order to render this communication method more natural, it was proposed to retain ordinary whiteboard and pens and to visually observe the writing process using a video camera [22, 25]. In this paper a prototype system for automatic video-based whiteboard reading is presented. The system is designed for recognizing unconstrained handwritten text and is further characterized by an incremental processing strategy in order to facilitate recognizing portions of text as soon as they have been written on the board. We will present the methods employed for extracting text regions, preprocessing, feature extraction, and statistical modeling and recognition. Evaluation results on a writer-independent unconstrained handwriting recognition task demonstrate the feasibility of the proposed approach.

Automated system for text detection in individual video images

Text detection in video images is a challenging research problem because of the poor spatial resolution and complex back- ground, which may contain a variety of colors. An automated system for text detection in video images is presented. It makes use of four modules to implement a series of processes to extract text regions from video images. The first module, called the multistage pulse code modulation (MPCM) module, is used to locate potential text regions in color video images. It converts a video image to a coded image, with each pixel encoded by a priority code ranging from 7 down to 0 in accordance with its priority, and further produces a binary thresholded image, which segments potential text regions from the background. The second module, called the text region detection module, applies a sequence of spatial filters to remove noisy regions and eliminate regions that are unlikely to contain text. The third module, called the text box finding module, merges text regions and produces boxes that are likely to contain text. Finally, the fourth module, called the optical character recognition (OCR) module, eliminates the text boxes that produce no OCR output. An extensive set of experiments is conducted and demonstrates that the proposed system is effective in detecting text in a wide variety of video images. © 2003 SPIE and IS&T. (DOI: 10.1117/1.1584050)

Text region extraction in a document image based on the Delaunay tessellation

In this paper, Delaunay triangulation is applied for the extraction of text areas in a document image. By representing the location of connected components in a document image with their centroids, the page structure is described as a set of points in two-dimensional space. When imposing Delaunay triangulation on these points, the text regions in the Delaunay triangulation will have distinguishing triangular features from image and drawing regions. For analysis, the Delaunay triangles are divided into four classes. The study reveals that specific triangles in text areas can be clustered together and identified as text body. Using this method, text regions in a document image containing fragments can also be recognized accurately. Experiments show the method is also very efficient.

色・輪郭特徴を用いた情景画像からの文字領域抽出手法

色・輪郭特徴を用いた情景画像からの文字領域抽出手法

Extraction of text regions from scenery images using multiple features

Extraction of text regions from scenery images using multiple features

EXTRACTION OF BIBLIOGRAPHY INFORMATION BASED ON IMAGE OF BOOK COVER

This paper describes a new system for extracting and classifying bibliography regions from the color image of a book cover. The system consists of three major components: preprocessing, color space segmentation and text region extraction and classification. Preprocessing extracts the edge lines of the book and geometrically corrects and segments the input image, into the parts of front cover, spine and back cover. The same as all color image processing researches, the segmentation of color space is an essential and important step here. Instead of RGB color space, HSI color space is used in this system. The color space is segmented into achromatic and chromatic regions first; and both the achromatic and chromatic regions are segmented further to complete the color space segmentation. Then text region extraction and classification follow. After detecting fundamental features (stroke width and local label width) text regions are determined. By comparing the text regions on front cover with those on spine, all extracted text regions are classified into suitable bibliography categories: author, title, publisher and other information, without applying OCR.

Segmentation of Page Images Using the Area Voronoi Diagram

This paper presents a method of page segmentation based on the approximated area Voronoi diagram. The characteristics of the proposed method are as follows: (1) The Voronoi diagram enables us to obtain the candidates of boundaries of document components from page images with non-Manhattan layout and a skew. (2) The candidates are utilized to estimate the intercharacter and interline gaps without the use of domain-specific parameters to select the boundaries. From the experimental results for 128 images with non-Manhattan layout and the skew of 0°∼45° as well as 98 images with Manhattan layout, we have confirmed that the method is effective for extraction of body text regions, and it is as efficient as other methods based on connected component analysis.