Questions tagged [computer-vision]

Questions about algorithms for processing and analyzing images and videos.

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How many different colors are possible to generate in the HSV Color Space using OpenCV?

I don't know if this post belongs in this site because I feel it might be a programming question, but also I feel it might be related to the way Color Spaces work, if it does't belong here I can ...
Nau's user avatar
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Accuracy of Digit Recognition with Template Matching

I have designed a C++ program to recognize the digits on an ID card based on OpenCV. First I preprocess the ID card image and then segment it based on contours. The segmentation results are as ...
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Is Local Binary Pattern gaussian distributed?

Local Binary Pattern is a way to determine a pixel, with a single number by comparing the center pixel with its neigbours. The result will be a binary number. Dos this number have a gaussian ...
euraad's user avatar
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optimization problem in CV

hopefully I'm writing this post in the adequate place if not please move my post I'm reading this paper about L-shaping fitting for vehicles. and ran into this optimization in the photo attached. in ...
shay ariza's user avatar
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Is the pinhole camera model appropriate for modelling a real camera?

I am developing a computer vision system, using the pinhole camera model. Is this an appropriate model to use for a real camera? I know that lenses and such will distort the image, my main questions ...
Iron filings's user avatar
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Wegihts for ViT-G/14 or ViT-L/16

I have been trying to find model weights for the above mentioned models, especially ViT-G/14 but have been unable to find it. The models are mentioned here https://paperswithcode.com/sota/image-...
ved jain's user avatar
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Design of opening structuring element

I want to find an appropriate structuring element so that only the indicated pixels (by X) are removed as a result of an opening operation, while all other image points remain unchanged. I know how to ...
voldemort's user avatar
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What might be a suitable clustering algorithm to split different parts in dense optical flow?

I want to split the main part(like people) in optical flow from the background, but I don't konw how to start. I think one way is to use some kind of clustering algorithm, first split the optical flow ...
zjnyly's user avatar
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Is it possible to measure how fast the humans are moving their bodies with different level(slow, normal, fast) from video?

Examples like swinging both of their hands squat walking around jump around etc Is it possible to perform this in real time under crowded scene without depth information? I can find out the "...
StereoMatching's user avatar
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grouping/clustering of lines using Hough transform

I am new to Hough transform, though I have some basic idea about it. I am currently trying to fit the best line to a cluster of points $\left(x_i, y_i\right), i = 1,2,\cdots , N$, where there are ...
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Computer Vision techniques to find the slope of the buildings with respect to the ground?

I want to find the slope of the building with respect to the ground which means that I need to find how tilted is the building with respect to the ground through computer vision or any other ...
Jaskirat Singh's user avatar
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How to show invariance under additive and multiplicative illumination changes

The task is to "Show that the transformation f -> ((ln fx)x, (ln fy)y) is invariant under additive and multiplicative illumination changes." From my lecture notes, for ((ln f)x, (ln f)y), ...
Autumn's user avatar
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3 answers
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How can I smooth thousands of faces in a 3D-mesh so as to end up with 6 faces of a die?

I have a 3D scan of an object with multiple faces, for example a standard 6 face die. The scan is a point cloud file of the die. I am able to convert the point cloud into a mesh and retrieve faces ...
ariel1987's user avatar
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Count the number of lines in binary image

Consider I have the following binary image (each pixel is either 0 or 255). How to count the number of lines (they could be straight or a little curvy). For example, in the picture, there are six ...
stood_room's user avatar
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Can computer vision process 3D “images” directly?

Most CV algorithms deal with 2D images produced by cameras. However, sometimes we need to process 3D “images” (I don’t know how to call them). For example, CT and MRI produce 3D radiographs. ...
哲煜黄's user avatar
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Interpreting results of Sobel Edge Detection

I am implementing A No-Reference Perceptual Blur Metric paper. Somewhere in the prep steps they mention the use of vertical Sobel filter for finding vertical edges. The algorithm is summarized in Fig....
Howisitgoing's user avatar
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Tolerance of object size variation for computer vision

relatively new to Computer Vision. Lets say for example, I have a sequence of images of a car driving away from a static camera into the horizon, and I want to use this image set for some bog standard ...
pikmin8's user avatar
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What is the best way to predict a continuous score based on image characteristics(pixels)?

I have a dataset with 9912 images, what is the best way to train them based on the pixels and features of the images to be able to predict a continuous target ranging from 1 to 100? The goal is to ...
nuno's user avatar
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Data source for Highway autonomous driving

I am working on a object detection system for autonomous driving. I have tried it in controlled environments. I would like to try it on videos taken from a camera in front of a car running on a ...
KansaiRobot's user avatar
2 votes
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792 views

Bold text detection

I am currently working on a project where I need to detect bold text on a multi font-size image (so no mathematic morphology possible). This detection will be used in parallel of an OCR system (with ...
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Which algorithm is most suitable for comparing two images to find differences?

I have two images of two objects that are suppose to be exactly the same. I use one for reference and one as my model. I want to find an algorithm that will help me find on which areas these images ...
Dan798's user avatar
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Morphological closing by axis-aligned rectangles for run-length-encoded binary images

A binary image is encoded as a sorted array of non-overlapping runs, which represent value 1. Each run is defined by $r$, $c_s$ and $c_e$, with $c_s \leq c_e$. These are the row, starting and ending ...
relatively_random's user avatar
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Why are point clouds useful for large datasets of geometries?

In my computer graphics course I came across this "pro" for point clouds: Useful for large datasets (>> 1 point / pixel) I'm trying to wrap my head about it, I know drawing is ...
Oli's user avatar
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Is multicolor vision really necessary for CV?

Having the ability to see 2 or more colors can improve the sensitivity of nuances but greatly increases the complexity of image processing algorithms. I once thought that 3 colors are necessary for ...
哲煜黄's user avatar
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Turing Machine for Check Validity of Unary Multiplication (A=B*C)

I have a lot of difficulty with the turing machines. I understand the theory well, but I need help with a lab exercise... Design a SINGLE TAPE Turing Machine that accepts the language $a = > b \...
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Methods to interpolate between 2 topologically identical 3D meshes

I have 2 3D surface meshes. These meshes have vertex-correspondence and have the same topology (same edges and triangles connecting the vertices). However, the vertex positions (3d coordinates) are ...
sanjeev mk's user avatar
2 votes
0 answers
58 views

L1 loss different scale for small or large boxes [object detection]

In this paper[1] there is a section where it is mentioned that “The most commonly used L1 loss will have different scales for small and large objects even if their relative errors are similar”. I don’...
user27286's user avatar
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Is it correct to perform feature distillation when both the teacher and student model architectures are completely different

When the architectures of the teacher and student networks do not just vary by network depths but are completely different, is it logically correct to distill knowledge at feature level (say from ...
Parandrea's user avatar
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Requesting help for monitoring data drift in instance segmentation model

happy to be here. I need some guidance. I am writing a project on data drift. I have trained an instance segmentation model on the Cityscapes Dataset, to detect pedestrians. The model I trained was on ...
jamba juice's user avatar
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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. ...
A_P's user avatar
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How to calculate image gradient with respect to homogeneous coordinate vector?

I want to use the direct method of computing the homography between two images to estimate the plane parameters (normal and depth [= distance from camera]) of a 3D plane. If we have two images of the ...
jiggy's user avatar
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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://...
Minty Fresh's user avatar
1 vote
1 answer
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Is the Jacobian matrix calculation process correctly on this energy function?

When I implemented the paper Dynamic Fusion published in 2015 CVPR, I came into the trouble with how to solve the energy function: $$E(W_t, V, D_t, \mathcal{E}) = \text{Data}(W_t, V, D_t) + λ\text{Reg}...
Jacob Chang's user avatar
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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 (...
jonjbar's user avatar
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2 answers
893 views

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 ...
UdevV's user avatar
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1 vote
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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 ...
Adria Ciurana's user avatar
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23 views

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 ...
yousef yegane's user avatar
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1 answer
40 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: ...
Peter's user avatar
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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 ...
gorb17's user avatar
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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 ...
David Jonsson's user avatar
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1 answer
69 views

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 ...
Hamza's user avatar
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0 answers
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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 ...
user130837's user avatar
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Stuck on Ejaz and Islam's paper about Masked Face Recognition

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/...
exius's user avatar
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1 vote
1 answer
284 views

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. ...
Shrey Joshi's user avatar
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0 answers
110 views

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 ...
Shrey Joshi's user avatar
1 vote
0 answers
316 views

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: \begin{equation} E = R \left[t\right]_x \end{equation} ...
holmeski's user avatar
3 votes
2 answers
124 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 ...
Arthur B's user avatar
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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 & \...
Blind's user avatar
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1 vote
1 answer
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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 ...
Hissaan Ali's user avatar
1 vote
0 answers
55 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 ...
Sara Ahmed's user avatar

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