Local Invariant Feature Descriptor Research Articles

A Modified Image Registration Algorithm Based on Color Invariance and RANSAC

Image category recognition and feature matching is an important access to visual information on the level of objects and scenes. So far, most works concerning local feature matching are limited in gray images. Designed for gray images, SIFT has been found to be a robust local invariant feature descriptor. However, much information is ignored since the color is discarded in traditional SIFT, and some mismatching problems happen due to this approach. To achieve a more accurate feature extraction and keypoints matching, more advanced method is desperately needed. In this paper, we present a group of color descriptors, to increase the performance traditional SIFT does in some occasions like outdoor scenes. Besides, a RANSAC algorithm is also analyzed and applied to our research, to leave out those obvious mismatching. RANSAC works well for images with many self-similar structures, which decreases mismatches significantly. Then we improved the method so that it converges in fewer iterations.

Distortion calibrating method of measuring rail profile based on local affine invariant feature descriptor

Measuring rail profile in the presence of multiple degrees of freedom vibration is a very challenging task. This paper presents a novel method based on the local affine invariant feature descriptor to calibrate distorted profiles, which are obtained by traditional rail measurement system. It has three major modules: local affine invariant (LAI) feature descriptor, affine transformation estimation and parameters refinement. LAI feature descriptor is based on the affine geometry invariant and generated by calculating the proportions of different areas. Using the proposed LAI descriptor, we implement a three-stage profile calibration including matching, estimation, and refinement based on grouping and fast iterative closest point (FICP) algorithm. The performance of proposed LAI descriptor and calibrating method is tested by performing extensive experiments. The experimental results show that our LAI descriptor is highly descriptive and robust with respect to varying resolution and noise, and the LAI descriptor based calibration is effective and repeatable.

Currency recognition using a smartphone: Comparison between color SIFT and gray scale SIFT algorithms

Banknote recognition means classifying the currency (coin and paper) to the correct class. In this paper, we developed a dataset for Jordanian currency. After that we applied automatic mobile recognition system using a smartphone on the dataset using scale-invariant feature transform (SIFT) algorithm. This is the first attempt, to the best of the authors knowledge, to recognize both coins and paper banknotes on a smartphone using SIFT algorithm. SIFT has been developed to be the most robust and efficient local invariant feature descriptor. Color provides significant information and important values in the object description process and matching tasks. Many objects cannot be classified correctly without their color features. We compared between two approaches colored local invariant feature descriptor (color SIFT approach) and gray image local invariant feature descriptor (gray SIFT approach). The evaluation results show that the color SIFT approach outperforms the gray SIFT approach in terms of processing time and accuracy.

위치와 색상 정보를 사용한 SURF 정합 성능 향상 기법

SURF(Speeded Up Robust Features)는 다양한 상태 변화에 강인한 기술자 추출 방법으로 객체 인식과 같은 분야에서 유용하게 사용되는 알고리즘이다. 이 알고리즘은 대표적인 특징점 추출 알고리즘인 SIFT(Scale Invariant Feature Transform)와 비슷한 성능을 보이면서도 수행 시간이 훨씬 빠르다는 장점이 있다. 하지만 이러한 기술자들은 회전 불변한 특징 보장을 위해서, 추출한 특징점 간의 위치 정보를 고려하지 않는다. 또한, 원본 영상을 흑백 영상으로 변환하여 사용하기 때문에, 원본 이미지의 색상 정보도 이용하지 않는다. 본 논문에서는 특징점들 간의 상대적인 위치 정보 및 색상 정보를 이용하여 SURF 기술자의 정합 성능을 개선하는 방안을 제안한다. 상대적인 위치 정보는 특징점들의 중심을 연결하는 선분과 특징점 중심에서부터 생성되는 orientation 선분 사이의 각을 기반으로 한다. 색상 정보의 경우 각 특징점이 포함하고 있는 영역에 대해 color histogram을 생성하여 사용한다. 실험을 통하여 제안된 기법의 성능 개선을 보인다. SURF is a robust local invariant feature descriptor and has been used in many applications such as object recognition. Even though this algorithm has similar matching accuracy compared to the SIFT, which is another popular feature extraction algorithm, it has advantage in matching time. However, these descriptors do not consider relative location information of extracted interesting points to guarantee rotation invariance. Also, since they use gray image of original color image, they do not use the color information of images, either. In this paper, we propose a method for improving matching performance of SURF descriptor using the color and relative location information of interest points. The location information is built from the angles between the line connecting the centers of interest points and the orientation line constructed for the center of each interest points. For the color information, color histogram is constructed for the region of each interest point. We show the performance of our scheme through experiments.

A robust multisource image automatic registration system based on the SIFT descriptor

Image registration is an essential step in many remote-sensing (RS) applications. This article presents a study of a multisource image automatic registration system (MIARS) based on the scale-invariant feature transform (SIFT), which has been demonstrated to be the most robust local invariant feature descriptor for automatically registering various RS images. The SIFT descriptor has two shortcomings: it is unsuitable for extremely large images and has an irregular distribution of feature points. Therefore, three steps are proposed for the MIARS: image division, histogram equalization and the elimination of false point matches by a subregion least squares iteration. Image division makes it possible to use the SIFT descriptor to extract control points from an extremely large RS image. Histogram equalization in prematching improves the contrast sensitivity of RS images. The subregion least squares iteration refines the registration accuracy. Images from multisensor systems, including Quickbird, IRS-P6, Landsat/TM, HJ-CCD, HJ-IRS, light detection and ranging (LiDAR) intensity images and aerial data, were selected to test the reliability of the MIARS. The results indicated that better registration accuracy was achieved, which will be very helpful in the future development of a registration model.

A Novel Image Correlation Matching Approach

In this paper we present a novel approach which is com bined local invariant feature descriptor named ARPIH (Angular Radial Partitioning Intensity Histogram) with histogram-based similar distance (HSD). The approach succeeds the ARPIH descriptor’s distinctive advantage and provides higher robustness in deformation image matching, such as rotation image, illumination changing image and perspective image, etc. Based on the MCD algorithm, we present the HSD algorithm . This algorithm transforms the image matching into the histogram matching by calculat ing the number of the similar points between template histogram and target histogram in order to decrease the calculation complicacy and improve the matching efficiency. A large amount groups of images are used in testing the approach presented in this paper. The matching results presented here indicate that the presented algorithm is efficient to figure out both the geometric deformation image matching and the illumination changing image matching. Contrast with the traditional matching algorithm, the approach presented in this paper has the obvious advantage of high matching precision, robustness and performance efficiency.