# Questions tagged [image-processing]

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474 views

### Space filling between random 2D lines

Note that I had asked this question in GIS forum, although it has gotten many up-votes, still has not received any answer. Hope you can break the silence, some collaboration :) Consider a region (...
226 views

### Why is Scale Space Needed to Detect Scale Invariant Features?

I have been doing research on the SIFT (scale invariant feature transform) algorithm, and while I have repeatedly read that in order to detect image features that do not vary with respect to scales of ...
61 views

### Metrics for image/visual complexity in computer vision/graphics?

Could anyone kindly point me to revenant literature in computer vision/graphics that detail on metrics for image/visual complexity and how to regularize that? More specifically, I am trying to design ...
356 views

### Stereo images rectification and disparity: which algorithms?

I'm trying to figure out what are currently the two most efficent algorithms that permit, starting from a Left/Right pair of stereo images created using a traditional camera (so affected by some ...
32 views

### Modifying the JPEG compression to use custom block patterns

recently, while watching a video about machine learning, I had an idea about creating an image compression algorithm, that works similar to JPEG, but is based on arbitrary bitmaps as blocks. I should ...
14 views

### impact of the single pixel in disparity

Disparity essentially means the distance of a corresponding pixel in another image ( in pixels). This is clear and understood. When I looked after how the depth is related to disparity, then I found ...
68 views

### What are some research papers or techniques that deals with fitting clothes on a human?

Given an image of a dress (from different angles), what could be ways to fit it on a human image (again multiple angles corresponding to dress)? Any link to research papers or tutorial regarding this?
205 views

### Simplify closed-path points without intruding into the inside of the path

I want to: Simplify a set of points that outlines a closed opaque image on a transparent background. The simplified set of points should not intrude into the closed opaque image. I use a Marching ...
587 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’...
17 views

### How are image processing and computer vision related to artificial intelligence.?

We have often heard both terms image processing and computer vision in AI sessions But i am confused, how they both are related to artificial intelligence?
22 views

### Evolving zero level set in images

I'm trying to implement a simple image segmentation application that accepts an initial contour and evolves it to compute a refined contour in successive iterations. I'm taking some inspiration from ...
20 views

### How to find the matched SIFT features that are spatially consistent?

I have extracted DenseSIFT from the query and database image and quantized by kmeans. The challenge is to find those SIFT features that quantized to the same visual ...
27 views

### Ghost outlines in image segmentation

If you observe the results of many image segmentation algorithms, you can notice the occurrence of region borders where a human observer wouldn't draw one, for instance across slow gradient/textured ...
1k views

### Comparing pixel density and number of pixel values

I am curious about an image processing algorithm used in this code pulled from this github repo. I have posted an explanation of the code below. ...
50 views

### How the SIFT results vary by changing some parameters

I'm studying the SIFT algorithm and I have some problem understanding its operation, in particular I don't understand how the results vary according to the parameters: number of octaves, number of ...
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 ...
186 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 ...
181 views

### Compare vectors, photo mosaic

I’m trying to make a photo mosaic web application. I split the main picture in to a number of squares. I split this square up in to 9 squares (See picture) Then I calculate the mean color (RGB) of the ...
13 views

### Does the illumination color (red/blue/green) has any effect over the disparity map generated from a stereo image?

I have a working model that creates a disparity map using stereoscopic image processing using opencv. I am thinking of improving the disparity map by using illumination and stuck with different ...
35 views

### Why is sparsity useful in dictionary learning?

What is the particular reason for which we use sparse matrix X in dictionary learning equation Y=DX where Y is the signal matrix, D is dictionary and X is the coefficient matrix?
45 views

### Transform Image Point to Azimuth and Elevation

I'm working on an object tracker where I need to report the azimuth and elevation of targets. Both values should be scaled from degrees to unsigned 32-bit integers. For now I can ignore lens ...
47 views

### How to find corresponding points between two photos when there's a repeated pattern?

Suppose that I have two photos, I1 and I2 and I want to find a set of corresponding points between the two photos to define a homography between them. There are many algorithms for this purpose, ...
51 views

### Comparing variable image to static image

What are Levenshtein distance algorithms, but for images? I will have one static image (the target: what it should look like) and one variable image (actual: what the user has created) For example, ...
20 views

### Multiphase levelset Chan Vese algorithm

I am implementing the multiphase level Chan Vese algorithm. I am using IPOL document as reference (http://www.ipol.im/pub/art/2012/g-cv/article.pdf) Everything is clear for me, except the stopping ...
304 views

### Backward mapping with bilinear sampler

I have some experiences with Convolutional Neural Networks before. I have a question regarding the Bilinear Sampler used in "Unsupervised Monocular Depth Estimation With Left-Right Consistency" (the ...
28 views

### Accept something with probability

I am reading the following paper https://pdfs.semanticscholar.org/5e86/db52119d2d691af0365cdba7bb27dc0dc303.pdf and trying to implement the tabu search algorithm they describe for image segmentation. ...
1k views

### Measure objects length and width by picture (pixels)

I am quite new to image processing. I have experimented with opencv and tried to measure the lenght and width of an object from a picture using a reference object where I know the dimensions. See ...
24 views

### Want to do 3D reconstruction via simple matching

I have 2 images, called left and right images. I have some matched points $[c_l,r_l]$ and $[c_r,r_r]$ in both of them (these points are in pixel coordinates). For a 3D point in the real world, they ...
46 views

### Finding a line shape objects (bars) in video images using neural networks (instead of Hough transform)

I'm currently trying to learn about computer vision stuff and I want to try it on a simple project of real time tracking of figures of players in a foosball game while the camera can be moving a ...
26 views

### Should I normalize values not bigger than 1

I have a question regarding a normalization of values especially in the case of image processing features classification. What if have a series of values that will never be bigger than 1. A = 0.004 0....
35 views

### What kind of numerical image features should I use to distinguish between the attached types of poses?

I've around $500$ binary (black and white) images, of which I attach $2$ samples. I'm working on a machine learning problem of classifying images like them. I'd like to know what image features I can ...
369 views

### Why are SIFT features significantly different after simply re-sizing image?

I'm new to SIFT and was surprised by how much the features changed after resizing an image. Here's the images I used for testing: Original: Resized: Cropped: After running SIFT on those 3 images, ...
50 views

### How to detect if objects are on top of each other?

Lets say we know the co-ordinates of each object in a camera co-ordinate systems. How do we find out if some object is on top of each other? My idea is: Compare each object and point with one another....
65 views

### Up to what extent the hypothesis of piece wise constant intensity values is valid in ocean images?

Usually, in MR images one hypothesis research communities are making is, " the spatial intensity distribution is piecewise constant and that each tissue corresponds to a unique grayscale level. Based ...
36 views

### Gradient Direction Equation: Color Value

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . On computing the gradient direction, given the equation: theta = ...
77 views

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 $... 0answers 85 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 ... 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 ... 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 ... 0answers 177 views ### Computer vision training procedures: SVM/AdaBoost vs Neural Networks With SVM, adaboost or similar alogrithms, image training sets must be cropped with specific constraints (keep image cropping ratio the same, have object tightly cropped, same resolution) In general, ... 0answers 217 views ### How to identify the z-ordering of objects in a computer vision or image processing scene? Given that there is an image with objects in it, is there any method in computer vision to determine the z-ordering of objects. For an ideal image of three circles overlapping, I can determine that it ... 0answers 762 views ### Improving MSE as fitness function for a genetic algorithm I am implementing an autoencoder neural network in matlab, the weights of which are being optimised by a genetic algorithm. At the moment I am working on the first layer, trying to get an improved ... 0answers 7 views ### Calculating spatial “orderedness” at each position in a binary image: entropy? lacunarity? Let's say I have image where all pixel values are either 0 or 1. What I'd like to do is to be able to generate a new image with the same dimensions where each pixel represents how "ordered" the area ... 1answer 28 views ### How to jump directly from level 0 to level 5 in a Gaussian pyramid without having the levels 1, 2, 3, and 4? I am current studying the Laplacian Pyramid as a compact image code by Peter J Burt and Edawrd Hudson. I understood all the concepts but I am having trouble with the equivalent weighting function. I ... 0answers 6 views ### Constructing a 3D virtual map from 2D Depth Maps and$x, y, z, \theta\$ coordinates

Context: I intend on building a quadrotor which can generate a 3D virtual map of an area of which it captures photos with a 2D camera. I plan on first training a Convulational NN to return a depth ...
22 views

### Training of two 3x3 convolution layers vs training one 5x5 convolution layer

I'm not 100% sure this is the right stackexchange, please feel free to redirect me to another one. I know that two 3x3 convolution layers can be equivalent to one 5x5 convolution layer. I also know ...
17 views

### Correct way to downsample a high-res image with jitter?

I'm new to image processing and I'm trying learn about image AA and upsampling algorithms such as those used in game engines. Engines tend to use jitter in order to get multiple samples from the same ...
17 views

### How to do mathematical morphology manually? Erosion, dilation, open, close

How do you do mathematical morphology manually? If you have a kernel or structuring element B1 do you move the origin of B1 to every pixel in the matrix A1 and see if it is a perfect match, partial ...