feature-detection

I use the HOGDescriptor of the OpenCV C++ Lib to compute the feature vectors of an images. I would like to visualize the features in the source image. Can anyone help me? I had exactly the same problem today. Computing a HOGDescriptor vector for a 64x128 image using OpenCV's HOGDescriptor::compute() function is easy, but there is no built-in functionality to visualize it. Finally I managed to understand how the gradient orientation magnitudes are stored in the 3870 long HOG descriptor vector. You can find my C++ code for visualizing the HOGDescriptor here: http://www.juergenbrauer.org/old_wiki

I have downloaded a sample code of Java OpenCV. In few lines of the code there is FeatureDetectore() method that the compiler says it's deprecated. FeatureDetector detector = FeatureDetector.create(FeatureDetector.MSER); detector.detect(mGrey, keypoint); listpoint = keypoint.toList(); So, How should I replace this part of code? Are there any new alternative for this? or can I continue use of the deprecated function? You can continue with this and this will work. Deprecation means that there is new recommended alternative, but off course old code will still work. The new way of doing that would

I've been working on a project where I stitch together images from a drone flying in a lawn mower pattern. I am able to stitch together images from a single pass (thanks to many answers on stackoverflow) but when I try to stitch two separate passes together laterally, the transformation my method produces is nonsensical. Here are the two images I am trying to stitch: And here is the code that I've been using to estimate a homography between the two, base and curr . base_gray = cv2.cvtColor(base, cv2.COLOR_BGRA2GRAY) curr_gray = cv2.cvtColor(curr, cv2.COLOR_BGRA2GRAY) detector = cv2.ORB_create(

I m working on small image processing assignment where I need to track 4 red color object. I got how to track single one. I want to know what is the best approach to track more than one point. There are 4 points which are positioned to form a rectangle so can I use shape detection or corner detection to detect and track the points Please see image below.. My naive implementation uses a technique described at OpenCV bounding boxes to do the tracking of red blobs. The following is a helper function used to retrieve the center of all the red objects that were detected: /* get_positions: a

I have been trying to figure out whether it's possible to nest CSS feature queries (also known as “CSS @supports ”) and regular media queries, and what would be the correct way to do it. Example A shows the feature query inside the media query. Example B shows the media query inside the feature query. Is it even possible to nest them at all? If so, is there a preferred nesting style? A or B? .foo { background: red; } /* EXAMPLE A */ @media (min-width: 50em) { .foo { background: green; } @supports (flex-wrap: wrap) { .foo { background: blue; } } } /* EXAMPLE B */ @supports (flex-wrap: wrap) {

Could OpenCV detect the geometric shapes which is drawn by hand as below? The shape can be a rectangle, triangle, circle, curve, arc,polygon,... I am going to develop an android application which detect these shapes. Well, I tried it in a harry. Normally you need to skeletonize the input. Anyway. You can reason about the shapes based on their points. Normally a square has 4, a triangle 3, etc. Effort results: Canny results: Polygonal approximation: Console output: contour points:11 contour points:6 contour points:4 contour points:5 Here is the code: Mat src=imread("WyoKM.png"); Mat src_gray

I am using openCV library on the android platform. I have successfully detected the largest rectangle from the image but since my application will be used for the scanning purpose ,i want to have the perspective change functionality as well. I know,how to apply perspectiveTransform and warpPerspectiveTransform,but for that i will need corners of the rectangle for the source points. It seems very easy to find the corners given the fact we have the coordinates of the first corner(Top-left) and width/height associated with the Rect object but the problem is ,for a rotated rectangle(usual

I have a video feed. This video feed contains several lights blinking at different rates. All lights are the same color (they are all infrared LEDs). How can I detect the position and frequency of these blinking lights? Disclaimer: I am extremely new to OpenCV. I do have a copy of Learning OpenCV , but I am finding it a bit overwhelming. If anyone could explain a solution in OpenCV terminology, it would be greatly appreciated. I am not expecting code to be written for me. Threshold each image in the sequence with a threshold that makes the LED:s visible. If you can threshold it with a