Questions tagged [computer-vision]
Questions about algorithms for processing and analyzing images and videos.
273
questions
1
vote
1answer
19 views
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 ...
1
vote
0answers
13 views
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 ...
0
votes
0answers
14 views
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 ...
3
votes
0answers
18 views
How to calculate 3D depth reconstruction of an image using a set of 3 similar images?
From a set of 2 similar images taken some small translation distance apart, we can calculate the depth of the a particular point, if we know the distance of a reference object in the frames. This is ...
2
votes
0answers
45 views
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 ...
0
votes
0answers
117 views
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 \...
0
votes
0answers
8 views
Hand Landmark Coordinate Neural Network Not Converging
I'm currently trying to train a custom model with tensorflow to detect 17 landmarks/keypoints on each of 2 hands shown in an image (fingertips, first knuckles, bottom knuckles, wrist, and palm), for ...
1
vote
0answers
9 views
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 ...
2
votes
0answers
29 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’...
0
votes
1answer
16 views
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 ...
1
vote
0answers
13 views
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 ...
1
vote
0answers
18 views
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.
...
1
vote
0answers
31 views
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 ...
0
votes
0answers
16 views
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://...
1
vote
1answer
49 views
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}...
0
votes
0answers
29 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 (...
1
vote
1answer
179 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 ...
1
vote
0answers
16 views
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 ...
0
votes
0answers
16 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 ...
0
votes
1answer
21 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:
...
1
vote
0answers
13 views
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 ...
1
vote
0answers
31 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 ...
0
votes
0answers
16 views
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 ...
0
votes
1answer
47 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 ...
0
votes
0answers
22 views
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 ...
0
votes
0answers
30 views
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/...
0
votes
1answer
33 views
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 ...
1
vote
1answer
40 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. ...
0
votes
0answers
36 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 ...
1
vote
0answers
95 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}
...
3
votes
1answer
38 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
...
0
votes
0answers
43 views
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 & \...
1
vote
0answers
19 views
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 ...
1
vote
0answers
40 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 ...
0
votes
1answer
39 views
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 ...
0
votes
1answer
55 views
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 ...
1
vote
0answers
34 views
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 ...
3
votes
0answers
20 views
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 ...
0
votes
0answers
34 views
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 ...
1
vote
0answers
21 views
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 ...
1
vote
2answers
108 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,...
2
votes
0answers
17 views
Contrast detection implementation for blur detection in microscopic image
I am currently doing a project where I have to detect if the the microscopic images given are blurry. I tried canny edge detection but they seem to perform not so good in detecting blur. I realised ...
0
votes
0answers
22 views
Laser Plane Estimation for Laser-Camera system?
I have to set up a system of a laser line/ plane projector and a web camera to localize the 3D position of the laser in the camera image. I've read / come across several resources but the idea is ...
1
vote
0answers
39 views
Image/Video deblurring
I am currently working on an algorithm that will help to improve shaken blurry images. I know there are plenty of them, such as deconvolution, that is pretty useful though I don't really know how to "...
1
vote
0answers
87 views
Why HOG angular bins have values between 0 and 180 degrees?
I have learned that HOG angular bins have values from 0 to 180 since the algorithm uses unsigned gradients. I am failing to understand why.
As far as I know gradient orientation is calculated as
<...
1
vote
1answer
46 views
Text detection in computer vision
I'm curious about the way text recognition works in machine learning(or more generally, the question of object vs not object) in computer vision.
How are systems trained when the not-object data set ...
1
vote
1answer
16 views
"higher intensity" and "high signal intensity" in images
I'm newbie in Computer Vision and image processing.
I'm reading the article "Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR" and it said:
2.2.4. WMH ...
0
votes
0answers
19 views
Measuring distance in arbitrary scale point cloud
I have one point cloud(point cloud of human feet) of arbitrary scale. If I have another point cloud(of human feet) with dimensions known, can I get the dimensions of a first point cloud? How will ...
3
votes
0answers
45 views
Partial derivatives of bilinear Sampling
I'm going over the paper Spatial Transformer Networks (link). On section 3.3 they introduce bilinear sampling kernel (Eq. 5)
$$
V_{i}^{c}=\sum_{n}^{H} \sum_{m}^{W} U_{n m}^{c} \max \left(0,1-\left|x_{...
2
votes
2answers
349 views
How to detect number of specific object in an image and it's diameter(size)?
I have two images of IRON RODS (i.e only two images) and I want to detect how many rods are there in each image and get the diameter of each rod in a image?
I don'...
