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Questions tagged [image-processing]

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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, ...
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14 views

Trace (horizontal) lines in grayscale image

I have a grayscale image with some line in it, which I would like to trace. The first image shows a Black&White version of the image, and the send shows the image after a few morphological ...
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1answer
49 views

(OCR ) How to Recognise Handwritten fractional numbers using Neural networks

I want to be able to recognise handwritten math numbers using images of the numbers , i was able to do create a ANN model for recognising simple decimal numbers , but i have no idea on how to ...
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3answers
36 views

How to prove that the erosion of a convex set by a convex set will result in a convex set?

How to prove that given convex sets A and B, the erosion of A by B will result in C - a convex set, too? I was given this question as a test-preparation, and I think it shuold be a proof, but I don't ...
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17 views

Question about Lens distortion

Suppose I have a 240x180 camera with the following distortion co-efficients, ...
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0answers
28 views

Calculating depth from disparity

I have seen equations for calculating depth from disparity values. I am actually trying to calculate one, but it is somehow difficult. First, I took two images with two webcams that have the same ...
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1answer
28 views

Matching/finding mathematical plot images

I'm trying to come up with a method to match a given mathematical plot against a database of other plots. To make it more specific: plots are generated in R as PNG and might have different dimensions. ...
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0answers
37 views

Front Portion detection of ring using opencv

I want to automatically detect front part of a earring within an image. Initially I though to find the blurry part within an image and remove it because some of the images are blurred at back side and ...
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0answers
21 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 ...
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1answer
38 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, ...
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1answer
59 views

Data structures that store efficiently detected features of an image

I struggle to find this, suppose I apply any feature detection algorithm. From my references it seems to me it's not usually explained what kind of data structures would be suitable for storing such ...
2
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1answer
41 views

The task of recognizing game units in the screenshot

I'm new to computer vision and I want to solve the task of recognizing the game units of the game Clash Royale in the screenshot. Briefly, there are about 70 different types of gaming units belonging ...
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1answer
25 views

Sample K representative frames within a video

I have an image-based processing module that takes photos for some computer vision processing. I have many videos, but I need to sample representative frames as its inputs, preferably those frames ...
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1answer
57 views

calculting distance between a person and the object in the image

Let's say a person took an image like this I have access to all image attributes (like for example image format, resolution and so on), and I know the location of the person - basically the place ...
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0answers
18 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 ...
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1answer
217 views

What is the difference between luma and luminance?

I understand the following (correct me if I'm wrong): Statements Luma as the weighted sum of RGB gamma corrected components, but luminance is the weighted sum of RGB linear components. The gamma ...
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0answers
95 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 ...
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0answers
140 views

How to recognize digits in water meter image

I need to read the digits of images like the one below: From what I understand, this will involve: Registering and segmenting the image into each individual digit Hand labeling a bunch of these ...
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1answer
51 views

Interpreting camera matrix

I'm having some trouble interpreting the camera matrix $K = \begin{bmatrix} f_x & s & x_0 \\ 0 & f_y & y_0 \\ 0 & 0 & 1 \end{bmatrix}$ after it multiplies some 3D vector. ...
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37 views

3-SAT reduction to image matching problem

I have a research paper, Elastic image matching is NP-complete by Daniel Keysers and Walter Unger, that illustrates the reduction from 3-SAT to an image matching problem in order to prove that this ...
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0answers
22 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. ...
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0answers
17 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 ...
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0answers
24 views

Open source implementation of Multiscale Combinatorial Grouping [closed]

I would like to use Multiscale Combinatorial Grouping for my PhD research. However, I am restricted to use open-source implementations and this one runs on Matlab. Does anyone know of an equivalent ...
2
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1answer
49 views

Is it possible to transfer a point from one camera to another, given n corresponding points?

I have 2 images of a scene taken at one moment by two identical cameras (similar cameras intrinsic parameters) by to arbitrary locations and at two arbitrary orientations (different cameras poses). On ...
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1answer
90 views

Algorithm for weighted elliptic curve fit

Background: I was trying to detect a face solely on the bases of features and the confidence of the features found. I am using a method to identify the features along with the response (confidence). ...
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1answer
53 views

Face recognition on on tilted images

From what I learned, viola jones needs images with faces upfront. Tilting the head a few degrees to each side can botch the algorithm. Is it possible to take an image, take a several rotated copies of ...
2
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1answer
85 views

What is the significance of the imaginary parts in the output of an Inverse Fourier Transform? Can I avoid them?

Starting with an image, I have taken its fourier transform and then modified it, and finally taken the inverse fourier transform of the modified fourier transform to get my resulting image. In my ...
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2answers
56 views

What is the best algorithm for image comparison in terms of speed?

Problem domain - I'm implementing a home monitoring system using smart phones. At regular intervals rear camera of the phone takes images and compare them for a change detection. This change detection ...
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1answer
97 views

Segmentation technique for handwritten text (cursive and unconstrained)

Although I am new to the computer vision domain, I am tasked with automating handwritten text recognition from bank cheques. I first did some preprocessing(blurring and binarization) and then dilated ...
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0answers
23 views

Edge detection using Image Morphology

Is it possible to do an edge detection using ONLY opening and closing operations? Where: opening- $X\bullet B = (X \ominus B) \oplus B$ closing- $X\circ B = (X \oplus B) \ominus B$ (I know we ...
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2answers
18 views

Distinguishing between side-by-side liquid streams

I'm new to computer vision and am looking for advice. I'd like to perform computer vision on a spiral system, in this system a down flowing liquid separates into different regions based on density: ...
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0answers
15 views

what interpolation method can I use for reliefs

I need to know which interpolation method is the best for working with reliefs, that is, to know the elevations or depths of a given terrain a set of points.
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0answers
661 views

opencv measure objects by pixels

I am trying to calculate the length and width of objects using a camera. The camera (90° angle from the top) and the background is fixed. See this Link https://www.pyimagesearch.com/2016/03/28/...
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0answers
844 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 ...
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1answer
65 views

How to identify object(s) in image when given a list of all images?

I see a lot of articles and topics about OpenCV and machine learning in regards to identifying general things (like cats, or alphanumeric characters) but I am wondering if something more specific is ...
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1answer
21 views

How to prevent the optimization algorithm from just shrinking the image?

I'm trying to optimize a set of patterns in an image, but unfortunately they only way I have of evaluating the images results in smaller versions of the pattern scoring much better than larger ...
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0answers
48 views

Recognizing features in images (uncontrolled environment)

I have been working for some time in several kinds of image recognition. They work well. One example is , character or shape recognition. I have implemented this in an embedded processor and I can ...
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1answer
21 views

What is the Code2 and other concepts of variable encoding in Coding Redundancy?

Am learning the concept of Coding Redundancy in image compression and am finding it hard to understand the table on page 3 of this document. All other explanations seem to follow the same symbols and ...
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0answers
22 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 ...
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0answers
67 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?
5
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1answer
129 views

Summed-area table for circular range queries

A summed-area table is a data structure and algorithm for quickly and efficiently generating the sum of values in a rectangular subset of a grid [Wikipedia]. Is there any algorithm for quickly and ...
5
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1answer
191 views

Bilinear Interpolation

I am trying to implement bilinear interpolation as described in the paper Spatial Tranformer Networks by Jaderberg et. al (see link to paper). They describe bilinear interpolation in Equation 5 as: $$...
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0answers
26 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 ...
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0answers
38 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 ...
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1answer
32 views

Feature selections : Still a high dimentionality

One of the advantage of using a features reduction/sub feature selection is to avoid a high dimentionality. The most known method is the Forward selection, where it finds the best combinations of ...
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2answers
80 views

Obtaining Image Measurements of a Known Object [closed]

Given the image of an adhesive tape as below, what would be possible method to find the tape radius? The image sepia toned with artificial background added. The tape itself is partially hidden.
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1answer
221 views

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

This question is purely theoretical as I've not been able to find anyone who's done such a thing, so my question is - is it possible, and if not why? Say you have a short video (CCTV) of a face, or ...
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1answer
43 views

How to predict the next image in a sequence, or predict the deblurring of an image?

I have 3 versions of an image at lower resolutions - 480p, 720p, and 1080p. Is it possible to use those 3 images to predict the next highest resolution image (the 4k image)? My first guess was that ...
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0answers
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....
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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 ...