# Questions tagged [image-processing]

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### 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 ...
• 11
1k 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 ...
27 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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1 vote
26 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: ...
19 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.
3k 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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1 vote
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 ...
• 11
618 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 ...
• 101
37 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 ...
• 101
77 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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1 vote
98 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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1 vote
27 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 ...
• 11
89 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?
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380 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 ...
• 451
681 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: ...
34 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 ...
1 vote
52 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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39 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 ...
99 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.
1k 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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1 vote
106 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 ...
1 vote
30 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....
1 vote
47 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 ...
• 129
2k 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. ...
124 views

### Convolutional Neural Network with constant kernels

I'm starting to learn about CNNs, and I have this question that I haven't been able to answer. Sorry if it is too basic. I know that in a CNN, the network learns to extract relevant features of ...
• 103
1k views

### Derivatives involved in Bilinear interpolation

If we choose a unit square in which the four points where the function $f$ is known are as shown in the diagram the interpolation formula for $f$ is: \begin{split} f(x+u, y+v)\approx (...
• 101
80 views

### Stroke Extraction to recreate Chinese characters

I was going through the project lists of Andrew NG from his Stanford machine learning course and I found a project based on recreation of calligraphic characters. To do so firstly we need to extract ...
101 views

### warm/neutral/cool tone of one image

I wanna determine whether an image belongs to warm/neutral/cool tone. I find Kelvin color temperature to calculate the average temperature of an image over all piexls. But the result seems not good. ...
133 views

### More Efficient Feature Method Than Haar-Feature For Face Detection

The seminal work by Viola-Jones had the most impact in face detection. It used Haar-Feature, which is fast to compute with the help of integral image method. Is there a feature method that is more ...
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108 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 ...
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45 views

### What is the best way to find similarity between two bodies?

Suppose we have two human bodies. We need to find some number that represents a similarity score between the two bodies. However in order to achieve that we need to find the similarity between the ...
• 101
1 vote
739 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, ...
555 views

### Algorithms to correct misspelled word?

At present, I am doing a project on Optical Character Recognition (OCR). I am looking forward to improve the results by checking the output words of my OCR code with existing words from a text file. ...
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1 vote
77 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....
1 vote
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 ...
76 views

### Color Filler Algorithm

Is there an algorithm that fills the area outside the edges? e.g.: From this to this
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1 vote
82 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 = ...
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1 vote
324 views

### Stroke Width Transform: Gradient Direction Computation

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . Having a simple image with random texts, that underwent gray ...
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390 views

### Stroke Width Transform: Gradient Direction and Rays

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . Having a simple image with random texts, that underwent gray ...
• 87
1k views

### Using landmark points on the face for face recognition

I am currently working in area of computer vision for my master's thesis and am trying to use distances between landmark points on the face for recognition. My question is this: What landmark points ...
38 views

### Any ideas on implementation of a certain image process?

I recently found this music video. While the music is mislabeled, the video part caught my eye. It seems to be transitioning between two images based on shape? I think its a fade-in/fade-out with the ...
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1 vote
228 views

### How does an image classifier select relevant features?

I am trying to understand cascade classifiers for computer vision. I use OpenCV Traincascade for now and successfully trained some cascades. However I am trying to grasp the whole process. One thing ...
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1 vote
197 views

### Basic queries for Object Detection using deep learning

I have recently started working on the Object detection using deep learning. I have understood the basic steps of object detection are: Input Image -> Object proposals -> Feature Extraction -> ...
1 vote
978 views

### Coordinates of the center and the radius of the circle on the image

What is the simplest possible way to calculate the coordinates of the center and the radius of the circle on the image (for example BMP and I'm interested in image of the Sun included below)?
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52 views

### Simple Recognition Algorithm, How Does It Work?

I am trying to understand how a simple image recognition of an image with dynamic size could work. What I have seen is that parts of the images are taken and evaluated. For example a simple finger ...
318 views

### Image registration algorithms for images with varying distances

I have two cameras side by side. I'd like to register two images taken from each camera. I think global transformation will not work for this issue since changes of distances between two images for ...
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360 views

### How to use PHOG and LPQ features for Emotion Recognition?

I have a database that consists of PHOG and LPQ features for each image. Now, I wish to train an SVM on these features for emotion recognition i.e SVM classifies the images on basis of emotion in the ...
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71 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 ...
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