Topic
Histogram equalization
About: Histogram equalization is a research topic. Over the lifetime, 5755 publications have been published within this topic receiving 89313 citations.
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07 Jun 2006
TL;DR: This paper presents a novel approach to boundary detection of regions-of-interest (ROI) in ultrasound images, more specifically applied to ultrasound breast images, and compares the performance of the algorithm with two well known methods.
Abstract: This paper presents a novel approach to boundary detection of regions-of-interest (ROI) in ultrasound images, more specifically applied to ultrasound breast images. In the proposed method, histogram equalization is used to preprocess the ultrasound images followed by a hybrid filtering stage that consists of a combination of a nonlinear diffusion filter and a linear filter. Subsequently the multifractal dimension is used to analyse the visually distinct areas of the ultrasound image. Finally, using different threshold values, region growing segmentation is used to the partition the image. The partition with the highest Radial Gradient Index (RGI) is selected as the lesion. A total of 200 images have been used in the analysis of the presented results. We compare the performance of our algorithm with two well known methods proposed by Kupinski et al. and Joo et al. We show that the proposed method performs better in solving the boundary detection problem in ultrasound images.
21 citations
01 Mar 2000
TL;DR: A flexible subblock image retrieval algorithm which is robust to object translation, lighting change, object appearance or disappearance in an image which is divided into 9 non-overlapping subblocks is proposed and clearly outperforms the global color histogram, R G B moments, and HS1 moments using the same method.
Abstract: In this research, we propose a flexible subblock image retrieval algorithm which is robust to object translation, lighting change, object appearance or disappearance in an image which is divided into 9 non-overlapping subblocks. Furthermore, using Ohta-color moments and biorthogonal wavelet frames from each subblock, we can reduce the dimension of color space and improve the performance. Also, as the two features are applied to the multistep k-nearest neighbor algorithm, this system clearly outperforms the global color histogram, R G B moments, and HS1 moments using the same method. In addition, we provide another retrieval environment for the user which is a relative block location search as well as an absolute block location search. In the case of the block location search, the user selects a block the user wants to search.
21 citations
TL;DR: A new approach to contrast enhancement which overcomes the mean-shift problem is proposed, which suggests a quantile-based division of the histogram of a given image, which can be used across the entire spectrum of grey level for contrast-enhancement.
21 citations
TL;DR: Comparisons among different dimensional features combinations were made to show that the proposed method outperformed that of traditional one with only basic color moments and texture distribution.
21 citations
TL;DR: The results evaluated by the binocular stereo-vision system indicate the reliability and performance in the stability water tank before the application to the obstacle-avoidance of the AUV.
Abstract: This study aims to develop a three-dimensional image reconstruction method based on the Laser Line Scan (LLS) technique to establish the binocular stereo-vision system for the preliminary research of obstacle detection technique of Autonomous Underwater Vehicle (AUV). A coordinate mapping relationship between 2D pixel coordinate and 3D world coordinate, which can be used to reconstruct 3D objects from 2D scan data, is established by means of direct camera calibration in air and water. In the experiments, the target object was originally designed by Computer-Aided Design (CAD) model and fabricated by the 3D printer. Subsequently, the qualities of point clouds acquired from the target object would be analyzed and compared in the stability water tank at National Cheng Kung University. The acquired point clouds would be used for polygonal surface estimation of the target object by Bonjean curve fitting method in water, with the reference results in air. The acquisition of raw point clouds has been accessed via the transformation to grayscale, histogram equalization, image binarization and skeletonization thinning. Consequently, the results evaluated by our stereo-vision system indicate the reliability and performance in the stability water tank before the application to the obstacle-avoidance of the AUV.
21 citations