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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1answer
58 views

Which is correct representation for function of variable?

I have a function as $$E=\int_\Omega -\log\big( p_i(x)\big) dx$$ where $p_i(x)$ is density distribution which estimated by Parzen window method. $$p_i(x)=\frac{1}{\Omega_i} ...
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2answers
40 views

Segmentation of small artifacts - Image Processing

I am working on a task of segmenting small artifacts from a set of images like below: I am looking for a generic approach, but unsure of what to search? I tried looking at density flow analysis, but ...
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0answers
9 views

Implementing Markov Random Field

I want to implement MRF for stereo vision.But I am a bit confused about the theory of the Belief propagation network. I create a graph, where nodes are the pixels and edges connect neighboring pixels. ...
3
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0answers
64 views

Removing noise from dental radiography

I'm working on a project of applying Active Shape Model to locate tooth in dental radiograph. For those familiar with the technique, I'm currently trying to sample along normal vectors for each ...
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0answers
10 views

Computer vision - What is the difference between appearance based and feature based in object recognition?

As English is not my first language, I have a little trouble in understanding these terms. I hope someone can explain this to me (if possible, in a simple to understand way). Plus, is there any other ...
3
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1answer
70 views

How to calculate particles sizes for spheric particles with overlapping and superposition? (Example image included)

I'm trying to automatically calculate particles sizes histogram for images like this one: Common threshold and segmentation doesn't seem to work. What filters and algorithms do you suggest to be ...
0
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1answer
24 views

How to filter objects on basis of orientation of regionprops

I am trying to detect straight vertical lines in an image. I used vertical edge detection and then I tried to check which objects has the ...
4
votes
1answer
71 views

Can deep neural networks achieve real-time video analysis?

Recently, convolutional neural network based, deep architectures (DNN) such as AlexNet and VGGnet have been very successful in image classification challenges (e.g. ImageNet) and action ...
0
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1answer
28 views

Finding crosses and their orientation on a given image

I want to recognize table structure from some arbitrary photo image and store it in some formal notation (Let it be HTML table notation). For example I have this blurry image as input: After ...
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0answers
8 views

Body Part Estimation from multiple depth images with occlusions

The is a number of works on the problem of body part estimation and it has widely been acknowledged that depth information helps in the problem. Most approaches I have seen so far work on the depth ...
0
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2answers
47 views

Image distortion and alignment on 3D mesh / pointcloud

Currently I have a fairly accurate (50 µm) and large dataset from a 3D scanner and a set of high resolution pictures. Sadly the 3D scanner (a Nikon/Metris arm-based CMM that was hanging around the ...
1
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2answers
42 views

Estimate camera generalized velocity from consecutive frames

Let's suppose I have a camera which can move freely in 3D space and has 6 degrees of freedom. Is it possible to estimate the linear and angular velocity of the camera from 2 or more consecutive ...
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0answers
12 views

Which kind of noise will show benefit with Guided filter

I am using guided filter function in MATLAB img_filtered = imguidedfilter(img_noise) I knows that guided filter is very good to preserving edge in noise image. ...
0
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1answer
47 views

What is different between gradient and imgradient functions in MATLAB

I would like to compute the gradient of an image I. I have the following two options : [Gx, Gy] = gradient(I); g = sqrt(Gx.^2+Gy.^2); or ...
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0answers
18 views

Retrive texture / data from photos of sphere object

I've built a photo box for taking photos of spherical objects (balls etc). I take photos cubical from six different angles. Now I want to extract the bitmap texture from the object with most ...
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0answers
21 views

How can a medical doctor use the information given by someone working in medical image computing(shape analysis)? Details follow

Posted also here, where it's been put on hold. I did modify it afterwards though. ...
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2answers
56 views

How to approach detection of anomalies in a video feed?

As part of a project I have a video from a quadrotor that captures the road and the environment around it and I want to identify and detect potholes and speedbumps on the road using image processing. ...
1
vote
1answer
39 views

Generate a nonuniform illumination (bias field) 2D image

I am creating a nonuniform illumination in MATLAB R2015. The nonuniform illumination (known as bias field) is defined as Nonuniform Illumination (intensity inhomogeneity) which manifests itself as ...
0
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1answer
53 views

How do I understand Fourier descriptors more visually and intuitively?

I read the book Image Processing, Vision and Machine Vision and find the concept Fourier descriptors hard to understand, although literally its derivation is somewhat reasonable. Can anyone give me a ...
1
vote
1answer
61 views

Good example for comparison between Guided and Gaussian filters

I am looking for a good example that showing the different between Guided and Gaussian Filters. The example need to show the benefit of Guided filter, (for example: preserving edge...). Could you give ...
1
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2answers
52 views

Seeking segmentation methods for this light microscope image

Although I am not new to math or programming, I am a total newbie to image segmentation. I have the following light microscope image and I would like to segment it into cytoplasm (the magenta ...
0
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0answers
30 views

Object localization down to the pixel

I am somewhat confused on the terminology used in Computer Vision. Suppose I wanted to detect (localize) an object (say, a human) in an image. However, a box around the human is not sufficient, what I ...
2
votes
1answer
39 views

Confusion regarding Sobel operator

I am taking computer vision course, where I learned about Sobel operator for detecting edges. I somewhat understand how it works as described here. But I have a basic confusion. The operator can be ...
0
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0answers
34 views

How to choose the threshold in uv disparity?

Several papers on uv disparity or v disparity state that once the uv disparity maps are computed a threshold should be applied. For instance in Alexandru Iloie UV disparity based obstacle detection ...
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0answers
22 views

Support Vector Machine is unable to recognize the digits in images properly

I am training a SVM on MNIST Handwritten digits database to make a basic digit recognizer. It is able to recognize digits easily on some standard images I took from a source. I then captured an image ...
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0answers
61 views

2D Convolution Along Only One Axis and MATLAB Implementation

I'm trying to implement a Depth Map algorithm for Light Field images and I stumbled in a 2D convolution of an image and a kernel, but I think that the convolution is only preformed along the x axis. ...
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0answers
63 views

How to match a thumbnail to an area in the original image?

Suppose that you have a thumbnail and the original image from which it was generated. You need to match the thumbnail to an area in the original image that represents the original selection from which ...
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0answers
10 views

How can I use a trained model to generate related images?

Suppose I have a data set of a large number of related images and I extract HOG features and train it using SVM Classifier or KNN Classifier. How can I use this model to generate a new image which is ...
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0answers
26 views

image processing: identifying connected regions based on regions' moments

Assume that I have the following grayscale image: and given that I have, for every segment of the different intensities (i.e. 1 black region with intensity 0, 1 gray with intensity 1 and 4 white ...
1
vote
1answer
55 views

NORM_HAMMING2 vs NORM_HAMMING

I'm trying to use ORB features with a cv::BFMatcher. ORB is based on binary descriptors so HAMMING must be the choice, but I'm not sure I understand the difference ...
0
votes
1answer
41 views

Extracting DCT coefficients from H.264/AVC bitstream

Is it possible to extract DCT coefficients from H.264/AVC bitstream without doing a full-decoding of the video? There are a lot of papers on compressed domain video processing which are based on the ...
1
vote
1answer
29 views

How the noise in time series can be reduced?

I have asked the question in the following link: Are time series data always contain noise? I wonder if we could use variational methods to denoise the time series data just as in computer vision? ...
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0answers
68 views

How to find the largest empty rectangle using OpenCV?

I need to find the coordinates of the largest empty rectangle in a PNG image. The rectangle should consist of light colors (if that is too difficult, white pixels only are fine) and should be ...
1
vote
1answer
41 views

Low Pass Filter - pixel correlation

I am trying to understand low pass filters for image processing, I came across an article that stated that low pass filters effect noise more than the real data due to that the image Noise always ...
0
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0answers
24 views

What techniques exist for segmenting particles given a priori knowledge of the particle size?

I am attempting to segment the following image, which consists of several circular particles that are surrounded by fringes. My goal is to create a mask that is black where a particle is located, and ...
0
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1answer
42 views

Can I segment characters from this image with CSV?

I am trying to segment my characters on this image with using column sum vector. This method actually works on the paper I've read about license plate recognition. it looks useful for my images ...
0
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1answer
55 views

How can I approximate a signal

I have a signal as the below figure. I am looking for some schemes to approximate the signal. I have found some ways for that task: Using basis function (polynomial) to approximate the signal ...
0
votes
1answer
20 views

camera calibration change orientation of axis

I want to solve for the extrinsics by using direct linear transformation on corresponding 3D LIDAR points and 2D camera points. I already have the intrinsics. Problem is, points behind the camera ...
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0answers
14 views

Essential Matrix from line correspondences

I'm looking for some library with a function to compute an essential matrix from line correspondences in multiple images. All the computer vision libraries I know use point correspondences to compute ...
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0answers
11 views

How is per-class rate defined?

I've recently read the following For our pixel labeling, consistent with [20], we report the number of pixels correctly classified (per-pixel rate) and the average of per-class rates. The ...
0
votes
1answer
23 views

Getting composition of a mixture of colours

I wanted to validate a thought on blending of colours digitally. Imagine I have two colours, $C_1$ $(R_1,G_1,B_1)$ and $C_2$ $(R_2,G_2,B_2)$. Now, I create colour $C3$ as follows: $C_3 = \alpha C_1 + ...
0
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1answer
49 views

Converting from RGB to Lab to reduce colors

In many papers I see the following: First we have to convert image from RGB to Lab color space to reduce colors then ...
-1
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1answer
22 views

How does the PASCAL VOC challenge evaluate the task of object detection?

I fail to understand the evaluation parameters like true positive, false positive and false negative in detection and classification tasks. can anyone help me to figure out what does each of these ...
0
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0answers
19 views

How to derive distance on flat floor to object in single camera image

With reference to the comment by @ Andrey Rubshtein in Is it always necessary to use two cameras to find the distance between camera and object? Another way is when you are located on a flat ...
0
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0answers
8 views

Training an object detector using “object present/absent” labels on image

I want to know the generic name for this technique of object detection: You're given a set of images labeled as "containing a cat" or "not containing a cat", and with this information you train a ...
2
votes
3answers
60 views

Background averaging not working

I'm working on a problem where I'm trying to use background averaging to see what the frame looks like in a beehive behind the bees. I've been trying to use standard averaging (I take an image every 1 ...
0
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0answers
16 views

Normalizing points gives worse result in DTL algorithm than no Normalizing

I am trying to find a homography for this images: I have to give a set of 10 points correspondencies between the two images. Then, I apply the DTL algorithm To find the matrix ...
1
vote
1answer
275 views

Rotated object detection by Viola jones Algorithm

In my project I need to detect rotated and non-rotated faces in real time. I read original articles and try to use common implementation in matlab and openCV. And as I understood Haar features are not ...
0
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0answers
18 views

Feedback Loops for Computer Vision

What image shape-detection algorithms exist that look in the neighborhood of starting parameters, rather than trying to find the "best possible fit" for image. For instance, I'd give a starting ...
0
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0answers
12 views

variattional calculus based 1d denoising

As of speaking about 1 d discrete denoising via variational calculus; I would like to know how to manipulate the length of smoothing term as long as it should be N-1, while the length of data term is ...