Skip to main content
15 votes

How to generate stereo image pair from a stationary mono camera?

You can't. You have video of the scene from a single vantage point. Without depth information, you can't infer what the scene would look like from another vantage point.
D.W.'s user avatar
  • 160k
11 votes

What is the difference between object detection, semantic segmentation and localization?

Since this issue is still not quite clear even now in 2019, and it might help new ML-Learners choose, here is a very good image showing the differences: (localisation is the bounding box around the "...
fogx's user avatar
  • 211
9 votes

How to generate stereo image pair from a stationary mono camera?

The terms you probably want to google for are "inferring depth maps". Just like your brain tricks you into seeing 3d if you close one of your eyes, you can heuristically recover depth maps from single ...
adrianN's user avatar
  • 5,951
9 votes

Convert HSV to RGB colors

This is my first post on StackExchange! I realize it's on a fairly old post but perhaps someone else will appreciate an explanation! I will preface this by saying that I come from a background in ...
MBearr1221's user avatar
7 votes

Google DeepDream Elaborated

The idea of DeepDream is this: pick some layer from the network (usually a convolutional layer), pass the starting image through the network to extract features at the chosen layer, set the gradient ...
Maxim's user avatar
  • 640
7 votes

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

I want to add one thing to @Dima's answer, just so things are absolutely clear: $E = (K')^TFK$ (note the transpose) You can see how this also captures that the fundamental matrix takes image ...
f.k's user avatar
  • 71
7 votes
Accepted

Computer Vision - What is spatial histogram/pyramid feature?

Spatial histogram. A simple histogram is obtained by taking a region of an image, assigning a label to each pixel (somehow; via some mapping function), and then computing a histogram of the labels. ...
D.W.'s user avatar
  • 160k
6 votes

Computer vision: Why do random filters perform similar to edge detectors?

Intuition, for a small case Why? Let's look at the simplest possible case, where the kernel is 1x2 (i.e., two pixels wide and one pixel high). Here's a kernel matrix for an edge detector that ...
D.W.'s user avatar
  • 160k
5 votes

Machine learning: do the benefits of more data plateau after a certain point?

Yes, typically there will be a plateau. There's usually no way to guess exactly where the plateau will be, a priori; the only way to find out is to build larger and larger data sets and see what ...
D.W.'s user avatar
  • 160k
4 votes
Accepted

Computer vision: object detection with labels that are single coordinates

The state of the art in such problems is done these days via deep neural networks. Among others, two popular and recent approaches for solving the problem of detection and localization of objects are ...
Nathaniel Bubis's user avatar
4 votes
Accepted

How is RANSAC used to estimate a homography given the descriptors of both images computed with SIFT?

How do you estimate inliers? You use RANSAC. That's what RANSAC does for you: it computes a homography and gives you a prediction for which pairs are inliers and which are outliers. In SIFT, we ...
D.W.'s user avatar
  • 160k
4 votes

Efficiently labelling training data in machine learning

You can't. You can't squeeze blood out of a stone. There's no such thing as a free lunch. You can't get something from nothing. If you want labelled images, you will need to label them yourself, ...
D.W.'s user avatar
  • 160k
4 votes

Computer Vision algorithm to tell if camera is moving?

An approach that is fast and seems to work well for me, and does not involve any fancy stuff, is to use the correlation of pixels over time as an indicator of motion: Make your video greyscale (lets ...
Peter's user avatar
  • 161
4 votes
Accepted

Difference between Image Analysis and Computer Vision

Maybe the web does not have an answer, but the classical book of Image Processing by Gonzalez and Woods has. I will summarize a part from a chapter that I have read. There is no clear boundary ...
pgmank's user avatar
  • 181
3 votes

What is 'real time' in a Computer Vision context?

In computer science, a real-time computing (RTC) system is one that guarantees a response before a previously set deadline. For a stream of images, that implies that a real-time system is one that ...
David Cary's user avatar
3 votes

What is 'real time' in a Computer Vision context?

There is no one answer to this question. "Real time" can mean very different things, depending on what kind of sensor or sensors you are using, and what you are trying to do. By the way, editing and ...
Dima's user avatar
  • 598
3 votes

Is it correct to use the pinhole camera model to get the mapping of a 3D line to a line in an image?

Please refer: Perspective Projection and Perspective Projection Matrix. Essentially pinhole camera is perspective view behind the camera. Since we need to divide the $z$ coordinate at places, we have ...
Sarvottamananda's user avatar
3 votes
Accepted

Is it correct to use the pinhole camera model to get the mapping of a 3D line to a line in an image?

The assumption is correct, if(f) you project the 3d line into the rectified image. The idea of projecting a 3d-line to a pixel-line is most often used in a stereo setup with two cameras: if the left ...
FooBar's user avatar
  • 197
3 votes
Accepted

Which algorithm for counting the occurrences of a certain pattern (spots) in an image?

The best way to get an orientation is to read a textbook on computer vision or image processing. There are lots of techniques known, and that's often the best way to get an introduction to a broad ...
D.W.'s user avatar
  • 160k
3 votes

What is the difference between object detection, semantic segmentation and localization?

I believe just "localization" means "single object classification + localization using a 2D or 3D bounding box". "Object detection" is localizing + classifying all instances of known object classes ...
Andrei Pokrovsky's user avatar
3 votes
Accepted

Is there a metric for the similarity of two image filters?

The ‘k-translation correlation’ is probably a good candidate for what you are looking for. It measures the maximum correlation between a pair of two filters $\mathbf{W_i}$ and $\mathbf{W_j}...
Simon Kohl's user avatar
3 votes

using orientation sensor data to predict image points

It turns out that I had two bugs that broke my experimental results: Even though the rotation matrix reports the rotation from Earth to Device, I should have been applying the opposite rotation to ...
Charles F's user avatar
  • 191
3 votes
Accepted

Given a low resolution video, is it possible to create a higher resolution image

It heavily depends on the setting, accuracy and goal, but shortly, yes, even considering practical application. Theoretically of course it is possible, with various (or used together) techniques like ...
Evil's user avatar
  • 9,455
3 votes

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

The Tomasi-Kanade algorithm is probably not used too much these days, though it is an important algorithm that provides a lot of insights and opens interesting avenues of research. I would say that ...
Richard Hartley's user avatar
3 votes
Accepted

Camera position w.r.t. basketball court

You said you could see lines, so I assume you could see their intersections. If you could assume to have at least 4 fixed points of the court which are always visible (corners might be a good choice), ...
David Taub's user avatar
3 votes

Sample K representative frames within a video

The question misses a lot of detail, so I will try to make an educated guess. I don't know of any specific algorithm for the task you are trying to achieve, but the first step towards your solution ...
João Gueifão's user avatar
3 votes

Computer Vision algorithm to tell if camera is moving?

Use background detection algorithm, say Gaussian Mixture-based background detection (present in OpenCv) and then make some assumption - say backround takes more than 60% of image. Then convert frames ...
Evil's user avatar
  • 9,455
3 votes

How to detect number of specific object in an image and it's diameter(size)?

Well to answer your last question, you cannot train with the images that you want to test your algorithm with, that is a paradox... You will need more than just two images if you want to build a ...
Théo Morales's user avatar
2 votes

Automated lip-reading: inferring what someone is saying, based upon video of them speaking

There is some recent work here: LipNet: Sentence-Level Lipreading. Yannis M. Assael, Brendan Shillingford, Shimon Whiteson, and Nando de Freitas. They achieve 93% accuracy on a corpus of 3-second ...
D.W.'s user avatar
  • 160k

Only top scored, non community-wiki answers of a minimum length are eligible