# Questions tagged [computer-vision]

Questions about algorithms for processing and analyzing images and videos.

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### Trying to figure out the best way to approach this problem with Computer Vision

Newbie to CV here so sorry of this is basic. Here's the deal, I have a program that I run many times. and each run I produce a screenshot. I need to compare screenshots from N-1 and N runs and make ...
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### Disparity calculations and camera centers

I'm learning about the disparity calculations and want to calculate the distance for a known pixel. I have calibrated and rectified images already. Now I just want to calculate Z for some pixel x,y. ...
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### How do we fix area of detectors in object detection?

I have gone through various articles on medium and also some from other sites trying to understand SSD. I am able to figure out most of the things from articles except this one. They always say that ...
118 views

### Do white box methods for feature extraction exist for facial recognition?

Part of something I'm working on (or rather begin working on) involves white box approaches to facial recognition. I previously worked on something for character recognition using scene segmentation ...
31 views

### Matching superimposed image

We are given two grayscale images, one of which contains a large, mostly contiguous patch from the other one. The patch can be altered with noise, its levels may be stretched, etc. Here's an example ...
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### Different types of interpolation used in computer vision

Known codition: four pixels shown in the image $(i,j),(i+1,j),(i,j+1)$ and $(i+1,j+1)$ $a=0.9$ and $b=0.4$ I was able to calculate the bilinear interpolation using the algorithm provided by https://...
28 views

### Will we be able to « see » COVID (or any other viruses) in our environment in the future?

Given that cameras, computer vision and AI are constantly evolving with greater zoom, macro, processing power... is it possible that some day cameras would be able to « scan » a room and detect COVID (...
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### What is the best way to compare two images for similarity if the brightness of the second image was changed?

I calculate similarity percent between two images. Another image is the same with changed brightness. I've already tried comparing by pixel (euclidean distance for grayscale and 0/1 values), comparing ...
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### How to correct distortion from stitching dual camera to estimate homography

I am trying to distort the image obtained from two cameras that generate a stitching image. Unfortunately, I do not have access to the cameras and I would like to know what could be the best way to ...
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### point of view of each pixel with regard to the whole image

I am looking for a technique or an algorithm that outputs a unique number/vector for each pixel of the image. I want to give the pixel a perspective so the neighboring pixels have more visibility and ...
20 views

### Distance transform with variable “impedance”

The distance transform gives the distance of each pixel in a mask to the nearest zero. E.g. lets take the Taxicab distance transform: ...
14k views

### What is the difference between the fundamental matrix and the essential matrix?

Could someone, in plain english, explain the distinction between the fundamental matrix and the essential matrix in multi-view computer vision? How are they different, and how can each be used in ...
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### Computer Vision Techniques to find Slope of beach in the 2D Images?

What I am planning to do is to calculate the height and estimate the slope of the segmented Object. The camera will be static and the Object of Interest is the slope of the beach. I am finding harder ...
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### Performing semantic segmentation on images on word documents

At the moment, I'm making a comparative analysis between two different neural networks for a class. The problem they are both trying to solve is detecting tables on documents. Below is an example of ...
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### Drawing a planar intersection from stereo camera

I wanted to recreate the results of this paper, where the authors draw the boundary between two parts of a building from stereo images. The authors mention that the epipole and the intersection of the ...
29 views

### Would a five color display have higher image quality than an RGB display?

We have five types of photo receptors in the eyes but computer color systems just use the three red, green and blue. Three could be motivated if rod and melanopsin sensations are just linear ...
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### How do I choose the right model for production?

I am trying to build a classification algorithm having 28 classes. These classes consists of Logo of companies like adidas , Nike etc. I have very low dataset below than 100 images and greater than 70 ...
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### Which pretrained model will be best for my dataset?

I am trying to build a classification algorithm having 28 classes. These classes consists of Logo of companies like adidas , Nike etc. I have very low dataset below than 100 images and greater than 70 ...
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### A few questions regarding simCLR

I read this paper obout simCLR and I didn't understand a few things: What is the goal of the temperature parameter τ? How does it affect the loss? What will be the value of the loss for a batch with ...
92 views

### Description of shape in a vector form

I would like to ask for references to algorithms that can project shape information about an object to 1 dimension. Specifically I am training a neural network to be able to identify objects with ...
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### Inverse VR-Vision, theoretical possibilities and the additional requirements

When using VR-Vision for looking around and the vision is from some point of interest, the look-around is a rotation from inside that point and it reqires a record of a 360° photo or a 360° camera ...
108 views

### Image selection for Object detection

I'm relatively new and am still learning the basics. I've used NVIDIA DIGITS in the past, and am now looking at Tensorflow. While I've been able to fumble my way around creating some models for a few ...
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I'm relatively new in machine learning and I am trying to put together my undergraduate thesis on masked face recognition. I've read Ejaz and Islam's paper (available at https://www.researchgate.net/...
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### I think I've found a flaw in this paper: On finding a minimal enclosing parallelogram. Can someone verify it for me?

On finding a minimal enclosing parallelogram I think the problem will occur when we only consider the first clockwise antipodal vertex. I think instead we should consider an edge when there are two ...
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### How to get a heatmap of pixel influences from a Convolutional Neural Network

If I have a CNN model (let's say I'm using Tensorflow and Keras) that I've trained for a particular task. For example, let's say I've trained it to detect the difference between an apple and banana. ...
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### Is deepfake detection viable?

I'm thinking of doing a project on deepfake detection, but I'm not entirely sure if it is viable. Based on my understanding, how it works is that deepfake generation programs have a generative and ...
625 views

### Is the Tomasi-Kanade factorization still commonly used as a modern computer vision technique?

My understanding is that, in very rough terms, the Tomasi-Kanade algorithm published in 1992 describes a way to reconstruct the 3D structure of an object from multiple images of that object, given ...
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### Interpreting the accuracy of solutions to the correspondence problem

I have two pictures of the same object, taken by a car travelling down the road like shown on the right side of the image below. I want to find pixels of the object in each frame that correspond to ...
68 views

### Using a rotation matrix to transform/shift a pinhole camera

I have a pinhole camera model with the following extrinsic (in Earth Centered, Earth Fixed Coordinate, (ECEF) system) and intrinsic parameters. focal length (x,y) = 55000 px, optical center = (2400,...
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### trouble recovering rotation and translation from essential matrix

I am having trouble recovering rotation and translation from an essential matrix. I am constructing this matrix using the following equation: $$E = R \left[t\right]_x$$ ...
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### Why can we not obtain a unique solution for orientation from Essential Matrix?

In computer vision, why cannot we obtain a unique solution for the projection matrix given an Essential Matrix. Why is it said that it can only be obtained upto 'scale' and what does this mean?
16k views

### Convert HSV to RGB colors

HSV colors are composed of a triple of numbers: hue $\in [0, 360)$ (in degrees), saturation $\in [0, 1]$ and value or brightness $\in [0, 1]$. RGB colors instead are more well-known and are also ...
33 views

### 3D Reconstruction from multiview calibrated camera

I have a calibrated camera whose intrinsics were calculated prior. Suppose I have multi images with the same camera. Using the first two views.I have the 1) initial reconstruction using 8 point ...
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### Are there some papers or books that compactly elaborate the essential part of the multiple view geometry?

I am a novice to visual SLAM and computer vision. Recently I've read a paper "A micro Lie theory for state estimation in robotics" dedicated to introducing the essential part that necessary to ...
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### Face recognition system with a sparse dataset

I have a dataset of 100 ID's, each ID with only a single unique face image. How can I develop an effective face recognition system to recognise only these faces? I was thinking Deep Learning but the ...
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### Computing structure tensors

As far as I understand, the structure tensor is:  M = \sum_{(x,y) \in W} \begin{bmatrix} I_x^2 & I_xI_y \\ I_xI_y & I_y^2 \end{bmatrix} = \begin{bmatrix} \sum_{(x,y) \in W} I_x^2 & \...
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### How is RANSAC used to estimate a homography given the descriptors of both images computed with SIFT?

Let image $x$ be an original (non-warped) image. Let $I_1$ be $I_1'$ having suffered some projective transformation and possibly some noise. Suppose we have computed SIFT descriptors for both images. ...
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### How are epipolar lines useful in computer vision?

Why do use epipolar lines and what are it's benefits in computer vision ?I am unable to find the uses of epiploar lines and how they are helpful although i am aware of epiploar geometry concepts. I ...
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### 3D reconstruction from multiple images

Sorry if it's a trivial question but I'am a beginner. I am working on 3D reconstruction from multi-images project. I am working with these datasets. There is a par.txt file including the camera ...
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### How can I compare two faces using facial landmarks?

I'm using first_order_model for an expression transfer between an video and a static image. Part of the algorithm makes a facial comparison to get the frame in the video where the face is best ...
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### Pattern detection by stacking convolutions

CNN use convolutions to perform many tasks. In some architecture, the first layer(s) are basic filters such as Gabor's. Many CNN work by stacking a number of convolution layers to build detectors ...
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### I don't understand formula meaning of computer vision Paper

I am master degree student at Computer Science Department. I started master degree at this year. Now I'm reading two papers about computer vision. Actually before time I didn't have experience about ...
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### What is the best algorithm for detecting the texture of a person's clothes in real-time for a mobile robot?

I am working on the human following robot. the robot extracts a feature of clothes's texture and distinguishes between the people that they stand up in front of the robot. So, the robot needs that it ...