检测、提取和匹配特征
局部特征及其描述符是许多计算机视觉算法的构建块。其应用包括图像配准、目标检测和分类、跟踪、运动估计和基于内容的图像检索 (CBIR)。这些算法使用局部特征来更好地处理缩放变化、旋转和遮挡。Computer Vision Toolbox™ 算法包括 FAST、Harris 和 Shi & Tomasi 角点检测器，以及 SIFT、SURF、KAZE 和 MSER 斑点检测器。工具箱包括 SIFT、SURF、FREAK、BRISK、LBP、ORB 和 HOG 描述符。您可以根据应用的要求混合搭配检测器和描述符。
App
| 图像配准器 | 配准二维灰度图像 |
函数
主题
- Local Feature Detection and Extraction
Learn the benefits and applications of local feature detection and extraction.
- Point Feature Types
Choose functions that return and accept points objects for several types of features.
- 坐标系
指定像素索引、空间坐标和三维坐标系。
- Image Retrieval with Bag of Visual Words
Retrieve images from a collection of images similar to a query image using a content-based image retrieval (CBIR) system.
精选示例
Image Retrieval Using Customized Bag of Features
Create a Content Based Image Retrieval (CBIR) system using a customized bag-of-features workflow.
Pattern Matching
Use the 2-D normalized cross-correlation for pattern matching and target tracking. The example uses predefined or user specified target and number of similar targets to be tracked. The normalized cross correlation plot shows that when the value exceeds the set threshold, the target is identified.
利用图像点特征在杂乱场景中定位对象
本示例演示了如何在杂乱的场景中，根据该目标的参考图像来检测特定目标。
Digit Classification Using HOG Features
Classify digits using HOG features and a multiclass SVM classifier.
自动检测图像旋转和缩放
本示例演示了如何自动确定两个图像之间的几何变换。具体来说，当一个图像因旋转和缩放而相对于另一个图像发生畸变时，可以利用函数 detectSIFTFeatures 和 estgeotform2d 来确定旋转角度和缩放因子。随后，可以利用这些参数将畸变的图像还原为原始外观。
创建全景图
本示例演示了如何将多个图像自动拼接成全景图。图像拼接的流程是基于特征的图像配准的延伸。与仅对单组图像进行配准不同，该方法将多组图像对依次相互配准，从而形成全景图。
Stabilize Video Using Image Point Features
Stabilize a video that was captured from a jittery platform. One way to stabilize a video is to track a salient feature in the image and use this as an anchor point to cancel out all perturbations relative to it. This procedure, however, must be bootstrapped with knowledge of where such a salient feature lies in the first video frame. In this example, we explore a method of video stabilization that works without any such apriori knowledge. It instead automatically searches for the "background plane" in a video sequence, and uses the observed distortion to correct for camera motion.
Object Counting
Use morphological operations to count objects in a video stream.
细胞计数
本示例演示了如何结合使用基本形态学运算符和连块分析，从视频流中提取信息。在此示例中，该程序统计了每个视频帧中大肠杆菌的数量。请注意，这些细胞的亮度各不相同，这使得分割任务更加具有挑战性。
