Questions tagged [computer-vision]

For questions related to computer vision, which is an interdisciplinary scientific field (which can e.g. use image processing techniques) that deals with how computers can be made to gain high-level understanding from digital images or videos. For example, image recognition (that is, the identification of the type of objects in an image) is a computer vision problem.

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16 views

Is there a way to estimate odometry using a single camera without a depth map?

Is there a way to estimate odometry using a single camera without a depth map? It somewhat seems like a circular problem since to estimate movement you need to know the change in object size, but you ...
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14 views

How to develop a model to detect a point crossed a line?

How to develop a system which detects if a object crosses a line. I am developing a system, basically which tells a object crossed a line. Do I need to get the camera calibration matrix ? Do I need to ...
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Can I train an object detection model with images with a white background?

To be more specific I have a dataset of 2400 images with unbalanced classes, 1 object per image and sometimes some objects are repeated along the dataset but in a different position and rotation of ...
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15 views

What is the state-of-the-art algorithm for neural style transfer?

I've read the paper A Neural Algorithm of Artistic Style by Gatys et. al. and I find the application of neural style transfer very fun. I also read that Exploring the structure of a real-time, ...
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12 views

Does the selective search algorithm in object detection learn?

I am trying to get a better grasp of how object detection works. I (almost) completely understand the concept behind RPNs. However I am little bit confused with the selective search algorithm part. ...
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46 views

How to make sense of label propagation formula in graph neural networks?

In the label propagation algorithm in section 3.2.3, we know the label of some nodes and we want to predict the label for the rest of the nodes whose labels we don't know. The update formula for this ...
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26 views

Since both RoI Align and PrRoI Pooling use bilinear interpolation, why is RoI Align discrete while PrRoI Pooling continuous?

I have two questions. Since both use bilinear interpolation, why is RoI Align discrete while PrRoI Pooling continuous? Could anyone explain the intuition behind the derivative of PrPool()?
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80 views

Combining clustering and deep learning for computer vision

Is there any recent work on combining clustering approaches (k-means, or gaussian mixture or PGM) with deep learning for computer vision? In particular I'm interested in if anyone has used the first ...
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Why can we perform graph convolution using the standard 2d convolution with $1 \times \Gamma$ kernels?

Recently I was reading this paper Skeleton Based Action RecognitionUsing Spatio Temporal Graph Convolution. In this paper, the authors claim (below equation (\ref{9})) that we can perform graph ...
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46 views

What is meant by “arranging the final features of CNN in a grid” and how to do it?

In the paper What You Get Is What You See: A Visual Markup Decompiler, the authors have proposed a method to extract the features from the CNN and then arrange those extracted features in a grid to ...
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31 views

What could be the possible strategy and Deep Learning method that MathPix might be using for LaTex detection?

I want to build an open Source OCR just like MathPix. There is already a model to extract LaTex from the image by Harverd NLP's im2markup but the problem is that their data has been trained and tested ...
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37 views

How to match faces with images in ID proofs

I'm working on a problem to identify whether a person's image matches with the one in his ID proof. The inputs are the real-time face image and scanned ID proof. Options that I'm thinking of Prepare ...
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32 views

Can I use augmented data in the validation set?

I am trying to predict nursing activity using mobile accelerometer data. My dataset is a CSV file containing x, y, z component of acceleration. Each frame contains 20-second data. The dataset is ...
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What is a heatmap in the CornerNet paper?

I have been working on understanding how CornerNet works, but I couldn't figure out a few parts about the architecture. First, the authors mention that there are 3 distinct parts to be predicted as a ...
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39 views

How is depth perception (e.g. in autonomous driving) addressed without using a Lidar or Radar unit?

For practical applications, like autonomous driving, depth perception is needed to make useful decisions. How is this normally addressed without using a LIDAR or RADAR unit (but using a camera)?
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Is it necessary to label the background when generating the labelled dataset for semantic segmentation?

When I label images for semantic segmentation (using u-net, if that matters), is labeling the background (anything I am not interested in) necessary? Will it improve the network's performance?
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22 views

Best ROC threshold for classifier?

Suppose I have a neural network $N$ that produces the output probabilities $[0.3, 0.8]$. Normally, I would specify a threshold of 0.5 for the argmax of the prediction, let's say, second arg > 0.5 ...
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21 views

Approaches for OCR building which can extract latex from the image as mathematical formulas

I have images of questions from the domain of mathematics, where the image can be a mixture of the English language and mathematical formulas. I want to build and train an OCR model like Harvard NLP's ...
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1answer
57 views

Why are RNNs used in some computer vision problems?

I am learning computer vision. When I was going through implementations of various computer vision projects, some OCR problems used GRU or LSTM, while some did not. I understand that RNNs are used ...
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1answer
42 views

How to prevent image recognition of my dataset with neural networks and make it hard to train them?

Suppose I have a private set of images containing some objects. How do i Make it very hard for the neural networks such as ImageNet to recognize these objects, while allowing humans to do it at the ...
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1answer
90 views

Is it possible to classify resistors using ResNet50?

I want to train ResNet50 model using resistor images like below: I tried it by collecting data from google images and there were quite few. So accuracy was very low (around %10) but I wonder If it is ...
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22 views

Computational difference between ANN and Pattern Matching

Conceptually, if you had an internal 3d model of all objects in CV you could do a scan matching algorithm. This algorithm would be ridiculously computationally intensive, but it would have a high ...
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Do we train the spatial net and temporal net separately in two stream CNN for action recognition from video frame?

In two-stream CNN paper, they have the following network architecture: We can use a simple average or multiclass linear SVM for the class score fusion. In the case of averaging the outputs of two ...
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41 views

Computer vision and deep learning with a small number of training images

I am using computer-vision for detecting objects on the measuring table. In my tests, I used two techniques/frameworks: semantic segmentation (framework TensorFlow) and object recognition (framework ...
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Which model structure is best suited to build a Math OCR (img2latex)? RAM, DRAM, CRNN or Attention OCR?

I am trying to build an OCR which can read the Mathematical equations just like MAthPix and im2markup. im2markup by HarvardNLP seems like a good model but the thing is that it is built using Torch and ...
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1answer
42 views

What are some good papers or resources for aspect extraction and opinion modelling from video or audio?

I am quite new to deep learning. I just finished the deep learning specialization by Professor Andrew NG and Deep Learning AI. Now, my professor (instructor) has advised me to look into some classic ...
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14 views

Can attention with 2d position encoding beat capsule on cv tasks?

I have always had doubts about the necessity and intuitive/theoretical justification for capsule network in image classification and more recently nlp tasks. For the former, in order to address the ...
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29 views

How to determine when the image is steady enough in a video sequence to take photos?

How do I calculate the points in a video sequence where the images are steady enough for a photo. For example, I want to take maybe 20 photos for a facial recognition dataset. Instead of asking the ...
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1answer
39 views

Can imbalance data create overfitting?

I am doing human activity recognition project. I have total of 12 classes. The class distribution look like this: $\color{red}{If \ you \ watch \ carefully, you \ can \ see \ that \ I \ have \ no \ ...
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2answers
128 views

What are the main algorithms used in computer vision?

Nowadays, CV has really achieved great performance in many different areas. However, it is not clear what a CV algorithm is. What are some examples of CV algorithms that are commonly used nowadays and ...
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75 views

What is a convolutional neural network?

Given that this question has not yet been asked on this site, although similar questions have already been asked in the past (e.g. here or here), what is essentially a convolutional neural network (...
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1answer
78 views

What are bag-of-features in computer vision?

In computer vision, what are bag-of-features (also known as bag-of-visual-words)? How do they work? What can they be used for? How are they related to the bag-of-words model in NLP?
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31 views

Overcome caveats on using Deep Learning for faster inference on limited performance availability

I am working in the field of Machine Vision, where accuracy and performance both play a major factor in deciding the approach towards a problem. Traditional rule based approaches work quite well in ...
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37 views

What is the reason for different learned features in upper and lower half in AlexNet?

I was reading AlexNet paper and the authors quoted the kernels on one GPU were "largely color agnostic," whereas the kernels on the other GPU were largely "color-specific." The upper GPU takes ...
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1answer
95 views

What is a fully convolution network?

I was surveying some literature related to Fully Convolutional Networks and came across the following phrase, A fully convolutional network is achieved by replacing the parameter-rich fully ...
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29 views

How to calibrate model's prediction given past images?

I want to predict how open is the mouth given a face image. It's a regression problem (0= mouth not open, 1=mouth completely open). And something between 0 and 1 is also allowed. ConvNet works fine ...
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1answer
38 views

Corner detection algorithm gives very high value for slanted edges?

I have tried implementing a basic version of shi-tomasi corner detection algorithm. The algorithm works fine for corners but I came across a strange issue that the algorithm also gives high values for ...
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1answer
47 views

How to choose a suitable threshold value for shi-tomasi corner detection algorithm?

While implementing shi-tomasi corner detection algorithm i got stuck at deciding a suitable threshold for corner detection. In shi-tomasi algorithm all those points that qualify ...
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1answer
32 views

Action recognition using video stream data

Recently, I am working on an action recognition project where my input data is from the video stream. I read some of the concepts like ConvLstm, Convolutional Lstm, etc. I am looking for someone who ...
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36 views

Which tool can I use to detect “visual defects” on a photo of a product?

I am looking for a tool that could detect visual defects on a photo of a free flowing product like potato flakes. Potato flakes is powder-like product that is essentially dedydrated mashed potatoes. ...
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140 views

Can we force the initial state of a neural network to produce an “unknown” class?

Has anyone investigated ways to initialize a network so that everything is considered "unknown" at the start? When you consider the ways humans learn, if something doesn't fit a class well enough, it ...
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25 views

Detect object in video and augment another video on top of it

I'm trying to detect an object in a video (with slight camera movement), and then augment another video on top of it. What is the simplest approach to do that? For instance, let's assume I have this ...
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27 views

How is visual attention mechanism different from a two branch convolutional neural network?

I am doing some research on the visual attention mechanism in remote sensing domain (where the features learnt from one layer are highlighted using the attention mask derived from another layer). From ...
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27 views

Merge two different CNN models into one

I have 2 different models with each model doing a separate function and have been trained with different weights. Is there any way I can merge these two models to get a single model. If it can be ...
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1answer
38 views

How does the math behind heat map filters work?

I am working on an app that generates heat/ thermal map given a picture. i have been able to get what i expected using python opencv builtin function ...
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1answer
25 views

How does the region proposal method work in Fast R-CNN?

I read so many articles and the Fast R-CNN paper, but I'm still confused about how the region proposal method works in Fast R-CNN. As you can see in the image below, they say they used a proposal ...
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1answer
42 views

How do you find the homography matrix given 4 points in both images?

I want to understand the process of finding a homography matrix given 4 points in both images. I am able to do that in python OpenCV, but I wonder how it works behind the scenes. Suppose I have ...
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25 views

An Encoder-Decoder based CNN to predict a tensor of points

So I have with me a data of rendered 2D images of a 3D object and along with that, I have the image projection coordinates (X, Y) of all the voxels that are in the ...
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1answer
27 views

How to use 'Canny/Watershed' algorithm's output as an input for Image Classification Model

I have a very silly problem in hand. I have implemented 2 methods which give me the mask to separate the objects from the background. What I get from one method is the object encapsulated in the red ...
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28 views

Why is this variable in equation 2 of the SQAIR paper a random vector of $n$ ones followed by a zero?

I've been reading the SQAIR paper lately, and the mathematics involved seems a bit complicated. Some background, about the paper: SQAIR stands for Sequential Attend, Infer, Repeat - the paper does ...

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