Questions tagged [image-processing]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
0answers
129 views

Image sharpening : Adding prewitt's filter resulted images. Is it correct?

I'm reading that 'Prewitt' filter is high-pass filter, which means that it can sharpening the image (via edge highlight). But I'm not sure to implement the sharpening process (not just edge detection)...
1
vote
0answers
77 views

Reduction of flow-shop scheduling to a real-world computing problem

Consider the following well known flow-shop problem: We are given a set of jobs $J=\{J_1,\ldots,J_n\}$ and a set of resources $R=\{R_1,\ldots,R_m\}$. Each job $J_i$ consists of a set of operations $...
1
vote
1answer
567 views

Circle Hough Transform. Improvement by knowing edge direction

I'm studying Hough Transform. I have fully understood the HT for detecting lines and successfully implemented it. I have more problems with the circle detection HT. Given a circle, if the radius is ...
2
votes
1answer
58 views

Extracting intersecting objects of the same colour from an image

What is the good way to extract the objects(circles) from image as shown in picture below? respectively create two images one with lines and one with circles from source image. I started with ...
1
vote
1answer
107 views

Is there any good way to judge whether the rectangle is inside the point cloud? [closed]

How to judge whether a rectangle in the figure is inside the given point cloud? For example, in this figure, the red rectangle is outside the point cloud and the green rectangle is outside the point ...
7
votes
1answer
2k views

Computer vision: object detection with labels that are single coordinates

Are there papers in the literature that address the following object detection task ? The task can be described as follows: Given a set of images, the labels are just coordinates (x,y) that ...
2
votes
1answer
3k views

What are the pros and cons of RANSAC versus Hough Transform?

A friend needs to find the pool balls in an image of a pool table. Would a Hough transform be a good idea? Why/why not? Would RANSAC be better? The question comes from this study guide (http://www.cc....
3
votes
1answer
578 views

HandyAR finger tip detection and tracking

I am reading this paper Handy AR. As suggested I am adding certain quotes from paper to get basic idea of what is it about : Intro In this paper, we present and evaluate a method to use a user’...
2
votes
3answers
85 views

Slicing clusters of non-black pixels from an image into separate images

The backstory I have spectrograms of certain repeating sounds. The background of the spectrograms are black and could easily be made transparent if that would help. The sounds are easily distinct ...
2
votes
1answer
641 views

Dynamically Learning Haar Cascade (in OpenCV)

I am new to computer vision so please excuse me if this question is very simple. I am trying to learn how to use the Haar Cascade creation tool provided with OpenCV to train a cascade classifier. It ...
1
vote
1answer
169 views

How are the number of bytes less than the number of pixels in an image?

Lets take, for example this jpeg image here The image there is 400 x 300, or 120000 pixels and The file size of the image (on my computer) is shown to be 65171 bytes. This means the computer stores ...
0
votes
1answer
464 views

Width of a String/Line in an Image

I have been looking for a method to find the width of a line. I found the solution(link: http://www.mathworks.com/matlabcentral/answers/88645-average-width-of-lines), "sum up the image to get the ...
1
vote
1answer
47 views

Computing gaussian kernel for image blurring

When I compute a gaussian kernel for image blurring should I normalize the 1D vectors? Because when I apply the raw values sometimes the image gets lighter or darker. The function I'm using is $f(x) = ...
1
vote
1answer
28 views

What is the need of re-sampling the image for HOG features?

I read Dalal and Triggs paper for HOG description and a blog Chris McCormick HOG regarding the same. The blog says that the image needs to be re-sampled at different scales to recognize different ...
0
votes
0answers
36 views

How do Perwitt and Sobel detect edges?

I read up on the Perwitt operator and it detects two types of edges (vertical and horizontal). The Sobel operator on the other hand does the same as the Perwitt except that the masks are not constant ...
4
votes
4answers
3k views

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

I have a stationary mono camera which captures a single image frame at some fps. Assume the camera is not allowed to move,how do i generate a stereo image pair of the acquired frame? Is there any ...
11
votes
1answer
210 views

Google DeepDream Elaborated

I've seen a few questions on this site about Deep Dream, however none of them seem to actually speak as to what DeepDream is doing, specifically. As far as I've gathered, they seem to have changed the ...
5
votes
1answer
373 views

Reconstructing a screen of permuted pixels

Reconstructing a screen of permuted pixels Summary Given a video with the pixel locations randomly permuted (once, for the entire video), can we (efficiently) reconstruct the original picture? Let: ...
4
votes
4answers
856 views

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

The Problem : Finding the number of occurrences of a certain pattern (or shape) in an image. In my example, the problem is about finding the number of spots (in variety of sizes) in an image. See ...
2
votes
1answer
156 views

High Dimensional Spaces for Images

Can anyone explain why pictures are not considered 2D, but rather high dimensional? Especially with regards to CV and AI.
1
vote
1answer
52 views

Register images from a camera which has undergone pure forward translation

Images are taken by a DSLR camera, always set at a particular Focal length. The scene contains objects with varying distance to the cameras. Since the camera has undergone translation, homography no ...
3
votes
1answer
58 views

Does JPEG compression use a heuristic model similar to MP3?

I know that MP3 uses a compression heuristic that allows it to exclude storing frequency data outside a certain range due to the limits of human hearing. Does JPEG employ some sort of non-linear ...
4
votes
1answer
172 views

perspective transformation of a grid

A perspective transformation of a point is defined as follows: $ x' = \frac{M_{11}x + M_{12}y +M_{13}}{M_{31}x + M_{32}y +M_{33}} $ $ y' = \frac{M_{21}x + M_{22}y +M_{23}}{M_{31}x + M_{32}y +M_{33}} ...
1
vote
1answer
166 views

Algorithms to convert 2D videos to 3D ones

Are there published algorithms that can convert 2D videos to 3D ones? If there are few published algorithms for this I am also interested to know how the conversion quality is.
3
votes
1answer
74 views

What is a visual bag of words and how is it implemented?

I'm currently working on implementing a bag of visual words in Python. I get the general gist of how it works but I can't seem to find any sources that explain it in more detail to a level where I can ...
3
votes
2answers
460 views

Meaning of topological distance between 2 pixels

I came across the notion of topology and topological distance in the context of image processing several times (especially when it came to mathematical morphology). I looked for a not too abstract ...
0
votes
0answers
60 views

Belief Propagation in Computer Vision

I am working on dense matching using DSP algorithm. They have used belief propagation to optimize their energy function? How do we do it? I mean how do we assign prior belief? Link: Deformable Spatial ...
1
vote
2answers
60 views

Reconstruction of drawing sequence from video

I have a video that record the drawing sequence with a pencil by a painter. I want to reconstruction the sequence from the video. And I have google some keywords like "drawing sequence reconstruction"...
4
votes
1answer
33 views

Inverting radial distortion

I'm trying to understand the math behind correcting a radial distortion (caused by a lens), but I'm failing to have it explained in simple terms. I found several examples that proceed this way: a ...
0
votes
1answer
117 views

Does the SIFT feature be calculated in the original image or the corresponding octave(s)?

Given there are 4 octaves(the 1st octave is the original image, the 2nd octave is half size of the original image, and so on.), does SIFT calculate the keypoint's orientation in the original image or ...
1
vote
0answers
84 views

Branch clustering for an MST

I am working in image segmentation with super pixels. My data is a large matrix describing various attributes of each stick of pixels (such as height, width and disparity). The data comes from an ...
3
votes
1answer
1k views

Removing common background in image processing phase for classification

I'm trying to build a machine learning classifier that can detect which object is in an image. I have a labled training set of images and am currently in the image processing phase. Each of these ...
1
vote
1answer
449 views

how to binarize an image?

I don't want to binarize a certain image through another program, I want to know how to binarize things myself. All I know is that there is something to do with a threshold and if it is above the ...
2
votes
1answer
20 views

Are there any articles or software which can infer original shapes from overlapping shapes?

Given that some shapes overlap in an image, are there any papers or articles or code which can infer the original shapes from the overlapping? I am thinking to apply some machine learning to this ...
3
votes
1answer
44 views

Fill in objects that pop out from background?

I need some help with a program that will fill in objects that pop out from the background. For example I have this picture and would like to get an output like this. I don't know how to do this ...
2
votes
0answers
93 views

Learning Image Processing/Computer Vision

What do I need to learn dense correspondence? I am a newbie in Image processing/CV. Please help me by suggesting a kind of syllabus or show me a way to learn about Dense Matching. What are the things ...
1
vote
0answers
99 views

How to train a Conditional Random Field/Markov Random Field Model for Object Classification in images given the features?

I want to classify superpixels in a image using a Markov Random Field/ Conditional Random Field model but have found no place that can help me with this (references don't even show how the network is ...
3
votes
1answer
116 views

Image Comparison tuned to Human Perception

Say I have two systems that take the same drawing commands and starts drawing on their respective platforms (i.e. HTML Canvas). After this is done, I want to save and compare these two images to ...
1
vote
1answer
38 views

Sources on dictionary learning and related algorithms

In the context of signal processing and sparse representation of signals, there is a topic called dictionary learning which is basically about how to's of the selection of basis functions used for ...
2
votes
1answer
2k views

What is the appropriate means of bias field in image processing?

I want to do image segmentation. In (Li, C. et al, 2011) article about A Level Set Method for Image Segmentation I saw that the authors use bias field estimation. I searched a lot but I couldn't ...
2
votes
1answer
68 views

Looking for Methods in Computer Vision for Distinguishing Disappearing and Fading Objects

Suppose I have a video in which there are two objects $A$ and $B$. Object $A$ appears suddenly at time $Ta1$, and then disappears suddenly at time $Ta2$. Object $B$ appears suddenly at time $Tb1$, and ...
2
votes
0answers
184 views

How to select a good window size in the Running Gaussian Average method for Selective Background Updating?

I have been studying the Selective Background Updating in Running Gaussian Average Method, as discussed in the Wikipedia (the Variant method). The details of the algorithm, as I understand, is as ...
4
votes
1answer
428 views

Register images containing objects with varying distance to the cameras

I'm learning about using image registration to align two images, e.g., two photographs of the same scene taken from a slightly different location. What factors influence how well we can align the ...
2
votes
1answer
34 views

Viewing images that compressed using lossless algorithms

I am just trying to understand a few minor details regarding images that are compressed with lossless algorithms such as RLE. If a bmp image is compressed using RLE, when does the decompression ...
0
votes
1answer
2k views

Clustering a set of images using keypoint descriptors

I'm trying to cluster around 16000 images into ~200 clusters, using kmeans with metric as euclidean distance or cosine distance. I understand that i need to extract keypoint descriptors to compute ...
2
votes
1answer
377 views

Selective Background Updating in Running Gaussian Average Method for Background Subtraction

I am studying the Running Gaussian Average Method for background subtraction. One alternative, as described in Wikipedia, also known as Selective Background Updating, is to only update the ...
3
votes
1answer
125 views

Multi object image segmentation methods

I want to survey the state-of-the-art in image segmentation. Is there a paper on how to segment multiple objects in an image? The segmentation papers I read, normally identify one of the many objects ...
1
vote
1answer
725 views

Intrinsic matrices in stereo camera calibration

Suppose I have two cameras, c1 and c2, observing the same scene. I can now Calibrate each camera independently (e.g., with MATLAB's Camera Calibration App) Calibrate both cameras simultaneously (e.g.,...
4
votes
1answer
3k views

Why does a color video compress better than a black and white video?

It was asked in an exam why a color video compress better than a black and white (grayscale) video using MPEG but can't find anything explaining it. In other words, we would apparently get a better ...
2
votes
1answer
56 views

Why does taking a gamma value > 1 make the image darker?

If I've understood gamma correction correctly (and I probably haven't), a gamma transform to an image raises the value of the intensity level of the input pixel to the power of gamma, where gamma can ...