Questions tagged [computer-vision]

Computer vision includes methods of processing, analyzing, images and high-dimensional data to form high level understanding and recognition of the scene or images.

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Matching features points of rotate image using SURF

I'm trying to match SURF points between 2 images using SURF with opencv. One is the rotation of the other. The problem is that the few matching it can found are wrong. image of matching points I ...
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2answers
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What is the procedure to obtain a 3D face dataset? Can anyone suggest a good 3D face dataset?

Project Description: Input: Frontal Face Image Expression Angle Size Details: I have to convert the input frontal face image into 3D face and simulate the ...
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4answers
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Scale and Rotation invariant Template Matching

I'm looking for a method for scale and rotation invariant Template matching. I already tried some, but they didn't work so good for my examples or took for ever to execute . SIFT and SURF Feature ...
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Projection Matrix (Computer Vision)

I'm trying to understand a piece of code that is using a camera projection matrix. The camera projection matrix $P = \left[\begin{array}{c}p_1^T \\ p_2^T \\ p_3^T\end{array}\right]$ takes a point $X$ ...
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Segmentation of half transparent material, e.g. glass

I'm totally stuck on an issue regarding the segmentation of glassy objects. I need to get the object as precise as possible. My approaches were different. At first I tried to remove the background, so ...
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1answer
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Compare image segmentation approaches

I've got a question related to a comparison of image segmentation algorithms. I'd like to compare two algorithm results to each other in step one. In another step I'd like to compare the two ...
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2answers
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Calculating a homography based on detected lines

I know you can calculate homographies from image to camera plane using correspondence points between a "perfect model" and the image points. I'm doing it for a football pitch/field, and have used ...
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1answer
180 views

Can anyone suggest good algorithms for CBIR?

Project: Content Based Image Retrieval - Semi-supervised (manual tagging is done on images while training) Description I have 1000000 images in the database. The training is manual (supervised) - ...
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2answers
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How does resizing an image affect the intrinsic camera matrix?

I have a camera matrix (I know both intrinsic and extrinsic parameters) known for image of size HxW. (I use this matrix for some calculations I need). I want to use a smaller image, say: $\frac{H}{2}\...
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2answers
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Recover myself from Dilate and Erode for noise reduction

i have obtained some skin detection map (i post below two example of detection map). but, i'm using a normal webcam and the map is noisy. Not a lot, just a bit. I think i can remove noise only with ...
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4answers
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Slicing and Recognition of book title and author from bookshelf image

I am trying, for my own learning purposes, to develop an implementation of an algorithm that would list books, given an image of a bookshelf like the following: The first step is to slice the image ...
46
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3answers
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What algorithm does Google use for its “Search By Image” site?

What is your best guess how Google Image Search works? I can upload a photo and can search for similar images. What algorithm does it use to identify similar images?
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1answer
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What are the state of the art methods for person segmentation and person pose identification

I know that HOG is pretty state of the art for person detection, but in its original form HOG is only a detection method, and I don't believe it is particularly fast either (there is a significant ...
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2answers
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Commonly used test image sets

In the image analysis literature there are a variety of ways people show the usefulness of their method. For example, performance on an ideal signal corrupted by noise, an artificial signal ...
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1answer
109 views

Methods for searching a large face database

I have a large face database, and I want to search through it. For example, if I input a new face image, the system would return the best N similarities. I know that PCA, LDA, and Procrustes analysis ...
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2answers
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Detection of a Circle in Noisy Image Data

I have an image that looks like the one below: I'm trying to find the radius (or diameter) of the circle. I have tried using circular Hough transform (via matlab's ...
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2answers
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Face Detection + Cropping

Project: Face Detection Description: I want to detect and crop a face in an image. The image is captured through webcam and only one face per image.I used OpenCV face detector, but I was not ...
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0answers
187 views

Red eye detection [closed]

Project: Red eye detection Description: I want to remove red-eye from images. I am not able to use face detector because, the faces in the images are not always frontal and also the images are of ...
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0answers
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How to categorize the images based on Illumination / shadow?

Input: Cropped face or Non Cropped face images. Detailed explanation: My project is face authentication. I am using OpenCV face detector to crop face from images. I am using OpenCV implementation of ...
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5answers
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Scale and Rotation invariant feature descriptors

Can you list some scale and rotational invariant feature descriptors for use in feature detection. The application is for the detection of cars and humans in video captured by a UAV, using a multi-...
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4answers
7k views

People detection from above

I am trying to find some method to detect people using only one camera 3 meters above the ground. This is a frame returned by camera: UPDATE: Video test -> http://dl.dropbox.com/u/5576334/...
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2answers
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recovery plane from 4 point imaging using calibration camera

I have a camera and its K matrix (calibration matrix) also I have image of plane, I know the real points of the 4 corners and thier correspondence pixel. I know how to compute the H matrix if z=0 (H ...
3
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1answer
257 views

Incorporating Radial Distortion in Imaging Model

I'm currently developing a multi-view stereo system but I'm confused as to how all the standard equations in Structure from Motion are affected in the presence of radial and decentering distortion. ...
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1answer
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Remove Shadows from Contour of an Object (Grapes)

I want to extract only the grapes from the images. Unfortunately, sometimes I don't get the grapes exactly. I have a code that doesn't work well in all cases. Sometimes, it does not differentiate ...
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1answer
77 views

FaceAuthentication

My project is Face Authentication. System Description: My input is only one image (which was taken when the user logins for the first time) and using that image system should authenticate whenever ...
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2answers
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Classification of Objects from a video/Image ( human,animals,others(cars etc.,) )

Moved from here SO Link. Hi I am new to image processing field. My project is to classify the objects in an image/Video. The input is an image/video from surveillance camera. I should classify the ...
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0answers
119 views

Sample keypoint found in multi-scale to one scale (scale space with O octaves)

For a multi-scale keypoints detector, local extremas are found between the scales at EACH octave. The scale-space is implemented as follows: Each octave is downsampled by half from the first image in ...
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2answers
376 views

Document image vanishing point detection and evaluation

It is a natural idea to substitute our scanner with mobile phone, and perform OCR with the phone at the same time. If this can come true, two problems must be tackled: one is related to document image ...
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2answers
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Sequentially get the outer contour of an Edge Image

Hi CV/Pattern Recognition Community, because my last thread was concerning the segmentation as BLOB and started to getting too big, with no clear results. I would like to reconcider the last step of ...
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6answers
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Image segmentation issue of different materials

Hi CV/Pattern Recognition Community, I've got a serious problem regarding the segmentation of an image. The scenario is an atmosphere within a furnace which makes my head go insane. And I need to ...
2
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1answer
329 views

How can I automatically find the boundary of a high intensity region inside an image?

I have an image I(x,y): Red indicates high values and blue low values. Everything in black is drawn onto the image afterwards. The black dot (xp,yp) represents a point clicked by an user and the ...
34
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7answers
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Finding squares in Image

I need to find the squares in an image using OpenCV (no problem in matlab or any other, generally what i expect are some ideas). Consider the test image below : I need to find those coloured squares ...
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2answers
789 views

Precision of Computer Vision algorithms

Let's say the task is to determine element position on image. First very important thing is correct detection of object then some algorithms of calculating position are used (for examble blob analysis)...
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1answer
662 views

Approximating pixel location in scale space

I'm implementing a scale-space with o octaves and s scale levels in each octave. Each octave is half the size the previous. I have keypoints found in each octave, I need to approximate the real ...
4
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1answer
200 views

What scale should a detected SIFT point be extracted at?

I've heard this from a few different researchers but I can't find a definitive value. Given the "scale" extracted by David Lowe's SIFT detector, we need to extract a descriptor at a specific scale. ...
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2answers
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Pedestrian counting algorithm

Currently I am developing a pedestrian counter project (using OpenCV+QT on Linux). My idea about the approach is: Capture Frames Do Background Subtraction clear noises (erode, dilate) find blobs (...
3
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1answer
9k views

EmguCV: Detect a ball in the frame

I am having a VERY hard time capturing when the ball comes into frame in this video http://www.youtube.com/watch?v=x1V6_OHrXIo I have no idea what to set the parameters too, and trying random values ...
5
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1answer
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Pose from Homography matrix - Zhang method

This post also contributes to the post at Step by Step Camera Pose Estimation for Visual Tracking and Planar Markers by Jav_Rock (since I cannot add any comment there and I don't know why) It can be ...
5
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1answer
502 views

Online boosting (training on the fly) for face detection

I want to implement an on-the-fly training process for face detection. I'm not sure but it seems it's called online boosting. Вefore, I have used OpenCV face detection with my own cascades, but I'm ...
5
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3answers
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Finding similar pictures in a database

I have large database of pictures, about a few million. I need an algorithm to find pictures which are similar to those in the database, up to a scale factor or a crop and shift (I have only these ...
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1answer
317 views

finding textures on images

I want to detect textures on images, for example after proccessing on image must be shown areas of each texture and area where is no texture.And I want to compute "mean" texture of selected area. ...
3
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1answer
141 views

scale invariant face similarity metric

I need some face similarity metric. I know about PCA,LDA approaches that uses raw pixels data, but they are not scale invariant(I know that I can resize image but I think that's not good solution). ...
2
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1answer
593 views

Color Tracking a Red Laser Height

I'm making a Laser Harp [https://en.wikipedia.org/wiki/Laser_harp]. The application needs the position of the hand along each of the laser beams to modulate a sound synthesis or modify the properties ...
4
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1answer
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Implement the 3D Structure Tensor in C/C++?

I am trying to figure out the details on how to implement the 3D structure tensor in C/C++ in an easy but efficient way and need some advice! For a discrete function $ I(x_i,y_j,z_k)$ the 3D ...
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2answers
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How to measure a lung nodule in a CT Scan DICOM image?

In this question, I would like to focus on intensity value of the CT Scan. First, take a look at the image below: The upper image is the original image, while the lower image is the thresholded ...
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3answers
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count blood cells

How to count blood cells in opencv? The problem is that they stick together. The example picture : Maybe pairwise geometric histogram (Geometric Histograms) suitable for matching partial circle ...
4
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1answer
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How are Object Recognition and Content-based Image Retrieval interlinked?

I need help on understanding the linkage between Object Recognition and Content-based Image Retrieval. Does OR use CBIR to find similar objects with the help of algorithms like SIFT etc or does CBIR ...
17
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3answers
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How to Detect Gradients and Edges in Images?

I want to be able to find points in images that are the centre of a radial gradient like the one shown in the left picture below. Any ideas on how I could use a Hough transform or some other computer ...
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0answers
65 views

Predicting Positional Displacement with a Bivariate Gaussian Distribution

In my computer-vision problem, a blob can move either forward or backwards (with a slight chance of moving sideways) along its directional axis. I am seeking a bivariate model because I need to ...
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2answers
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Algorithms for detection of fingertips or nails

Can you give me some advices on what could be the best algorithm(s) to use for detection of fingertips/nails in image. First thing that crossed my mind was Viola - Jones. After rethinking I concluded ...