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Questions tagged [computer-vision]

Use this tag for questions related to Computer Vision -- any aspect of software that enables computers to perceive, understand and react to their environment using cameras. For questions related to image filtering and quantification, use the tag [image-processing] instead.

Computer vision enables images, or sequences of images, to be processed by a computer using algorithms. There are many aspects to computer vision, including mathematics, physics (especially optics), imaging hardware, , and .

Some basic techniques used in computer vision are:

  • Image acquisition
  • Pre-processing
  • Feature Extraction
  • Detection/Segmentation
  • High-Level processing
  • Decision making
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OpenCV Documentation for Android

I am a newbie to the area of computer vision, with no prior experience. I am trying to develop a face recognition app for Android devices using OpenCV. I have installed OpenCV, but I have no idea how to use it. It seems like there is no Android…
user1210233
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Hardware to use for 3D Depth Perception

I am planning on giving a prebuilt robot 3D vision by integrating a 3D depth sensor such as a Kinect or Asus Xtion Pro. These are the only two that I have been able to find yet I would imagine that a lot more are being built or already exist. Does…
clifgray
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Project 2d points in camera 1 image to camera 2 image after a stereo calibration

I am doing stereo calibration of two cameras (let's name them L and R) with opencv. I use 20 pairs of checkerboard images and compute the transformation of R with respect to L. What I want to do is use a new pair of images, compute the 2d…
Sassa
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Detecting small circles with OpenCV (bad image quality)

I'm trying to detect the four dots you can see in the center of this picture: This one is converted to png, I actually use a ppm format (after conversion from raw output from the camera). The actual processed image is available here I'm new to…
Wojtek
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vlfeat matlab error Attempt to execute SCRIPT vl_imsmooth as a function:

I am trying to use the VLFEAT function vl_imsmooth but matlab gives me an error: 'Attempt to execute SCRIPT vl_imsmooth as a function:' Why this happens? Might it be because of some mex files? Should I recompile the c++ code for vl_feat?
user570593
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Fingertip Detection in c#

I'm just wondering about how the fingertips of a hand gesture are detected. I am using this finger counts for finger spelling. More specifically, I am working on C# with AFORGE.NET and want to use convex-hull algorithm for it. Everything I can find…
tnchalise
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How to make a charcoal drawing filter

i'm interested in some kind of charcoal-filters like the photoshop Photocopy-Filter or the note-paper. Have someone a paper or some instructions how this filter works? In best case i want to create the following: input: Output: greetings
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Error in OpenCV 2.4.2 "OpenCV Error: Bad flag"

I just started trying to play with OpenCV and I wrote a small program from a book that is pretty simple. The problem is when I try to compile it, I get this error. I will give you all the information I have. I installed openCV using homebrew for…
Red
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Corner detection algorithm for mobile

I am trying to find a good algorihtm that would detect corners in a image in a mobile phone. There are multiple algorithms to do that I am not sure which one will perform better in a memory and processor limited environment. Specifically I am…
Szere Dyeri
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Color classification with k-means in OpenCV

I want to cluster a lot of images with the K-Means Algorithm. I want to set up the clusters, so that each cluster represent the dominant color or the hue of the image. I've read something about this in the paper Colour Image Clustering using…
501 - not implemented
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Measuring an object from a picture using a known object size

So what I need to do is measuring a foot length from an image taken by an ordinary user. That image will contain a foot with a black sock wearing, a coin (or other known size object), and a white paper (eg A4) where the other two objects will be…
mar
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Reconstruct 3D-Coordinates in Camera Coordinate System from 2D - Pixels with side condition

I am trying to reconstruct 3D-Coordinates from the 2D-Pixel-Coordinates in a Camera Picture using a side condition (in MatLab). I do have extrinsic and intrinsic camera parameters. Using homogenous transformation I can transform 3D-Coordinates from…
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OpenCV findcontours returns 2 contours for each circle

I am trying to use findcontours() function in OpenCV on the image below. findContours(img, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE, cvPoint(0,0) ); When I do this query: contours.size() it returns 18, so that seems 2 contour for each…
dr_rk
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Why is my SIFT implementation only finding flat regions?

I am trying to write an implementation of SIFT, just as an excercise. However, I'm running into problems that I haven't been able to figure out yet. As far as I can tell, what I'm getting is the opposite of SIFT: it finds uninteresting, flat areas…
shitty_sift
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How to detect architecture and sculpture in opencv?

can someone tell me how i can detect pictures of architecture or sculpture? I think hough-transforming is a good approach. But i'm new in CV and maybe there a better methods to detect pattern. I heard about haarcascade. can i take this for…
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