Questions tagged [image-processing]

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Interpreting results of Sobel Edge Detection

I am implementing A No-Reference Perceptual Blur Metric paper. Somewhere in the prep steps they mention the use of vertical Sobel filter for finding vertical edges. The algorithm is summarized in Fig....
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Algorithm to find best alignment of one curve onto another

So I've boiled a certain problem I have down to the point where I have two images of (approximately) the same scale. One which contains a closed curve, and one which is a partial curve. I want to ...
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What is the best way to predict a continuous score based on image characteristics(pixels)?

I have a dataset with 9912 images, what is the best way to train them based on the pixels and features of the images to be able to predict a continuous target ranging from 1 to 100? The goal is to ...
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What is "energy" in computer vision

I keep seeing the term "energy" used in computer vision literature, specifically when speaking about Image Segmentation. For example on this page on Graph-Cut. I'm just wondering if someone ...
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Fast Algorithm To Compute Gradient Of Gaussian Blur

what is the fastest algorithm to compute the gradient of the Gaussian blur of a (grayscale) image, with a blur radius of around 100 pixels, where smoothness of the result is important to me, i.e. no ...
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preprocessing or real time for magnification of portions of video

Im new at CS and would like to gather preliminary information to approach an interactive art project. I want to construct a grid of videos - think about a matrix M = m x n where Mi,j is a video that ...
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Prove that union of connected sets is a non-connected set

Studying for my finals in Image Processing. In one of the exams there was the following question related to mathematical morphology: Given an image with two sets of pixels $A$ and $B$ connected and ...
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RGB synthesis in pixels in a computer

A pixel is contained of 3 ranges of RGB color synthesis to add colors into a tiny-square small box, as I learned (correct me if I am wrong). But, through these 3 colors admixture can we create any ...
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What is the difference between discriminative information and diverse information in computer vision?

I am studying deep learning and found a lot of papers in which they tried to distinguish between discriminative information and diverse information. What disctiminative and diverse information mean? ...
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Which algorithm is most suitable for comparing two images to find differences?

I have two images of two objects that are suppose to be exactly the same. I use one for reference and one as my model. I want to find an algorithm that will help me find on which areas these images ...
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How to calculate 3D depth reconstruction of an image using a set of 3 similar images?

From a set of 2 similar images taken some small translation distance apart, we can calculate the depth of the a particular point, if we know the distance of a reference object in the frames. This is ...
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2D fourier transform

I an new to image processing and I have some questions I want to understand: What is the meaning of the imaginary and real part of the 2d fourier transform? What can it tell me about the image it ...
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Computational complexity of median filter in image processing

I found this paper http://nomis80.org/ctmf.pdf, that describes an efficient algorithm for applying a median filter to an image. Though this works for non-HDR images, I am not sure how well it scales ...
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How many unique Huffman codes can you make. Image I has size 256x256 and has pixels of values 50,100 and 200

Let I (M x N) be an image made only of 3 pixels, how many unique Huffman code can you make (example: Image I has size 256x256, and has pixels of values 50,100 and 200). If someone can help me how to ...
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Predicting continuous variables using image and text input to neural network

I am looking to create a neural network architecture that takes two kinds of inputs: image and text, and outputs a predicted continuous variable. More specifically, I will have multiple images of a ...
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How many pixels support each neuron in multi-layer CNN?

I'm studying for a computer vision module and I'm on the deep learning topic, in one past paper we have the following question: Given that a convolutional neural network has five convolution layers (...
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What is an algorithm to do this binary image segmantation task?

What I need to do is go from a binary image like this: to a segmented structure like this: because I have a program that operates on those separated line contours after. As you see, those contours ...
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2 answers
325 views

What is the best way to compare two images for similarity if the brightness of the second image was changed?

I calculate similarity percent between two images. Another image is the same with changed brightness. I've already tried comparing by pixel (euclidean distance for grayscale and 0/1 values), comparing ...
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point of view of each pixel with regard to the whole image

I am looking for a technique or an algorithm that outputs a unique number/vector for each pixel of the image. I want to give the pixel a perspective so the neighboring pixels have more visibility and ...
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1 answer
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Inverting an image, as a matrix

I am curious about something pretty simple, though I have never heard, read and more sadly seen any example of it. Take any image, represent it as a matrix, invert the matrix (assuming the inverse ...
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Which pretrained model will be best for my dataset?

I am trying to build a classification algorithm having 28 classes. These classes consists of Logo of companies like adidas , Nike etc. I have very low dataset below than 100 images and greater than 70 ...
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1 answer
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What is a task type?

I have an unlabeled dataset: 500 X-rays of seeds in husk. In each image there are different number of seeds, for instance, from $10$ to $50$. A seed has some features. The main features are a seeds' ...
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Affine transformations for twisting and pinching

In image processing we can use affine transformations for translation, rotation, shear and scaling of pixels. But what kind of transformations are used for twisting and pinching of image pixels? Or ...
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Inability to understand local fourier analysis in the given link

https://www.researchgate.net/publication/235662494_On_separating_overlapped_fingerprints [Paper name-"On separating overlapped fingerprint", author-Fanglin Chen,Jianjiang Feng,Jie Zhou] I ...
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2 votes
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35 views

approximate line segments from array of unsorted points

The polygon above is actually a collection of a lot of black points closely packed together. I want to approximate these black points as straight line segments. The black points are not sorted in any ...
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A pretrained model for mathematical equations characters detection

I am working on a project to convert equations to LaTeX code. After segmenting out the characters, I got stuck on the detection part and was looking for some pre-trained model that could detect ...
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1 answer
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How are epipolar lines useful in computer vision?

Why do use epipolar lines and what are it's benefits in computer vision ?I am unable to find the uses of epiploar lines and how they are helpful although i am aware of epiploar geometry concepts. I ...
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1 answer
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Performing semantic segmentation on images on word documents

At the moment, I'm making a comparative analysis between two different neural networks for a class. The problem they are both trying to solve is detecting tables on documents. Below is an example of ...
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I don't understand formula meaning of computer vision Paper

I am master degree student at Computer Science Department. I started master degree at this year. Now I'm reading two papers about computer vision. Actually before time I didn't have experience about ...
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4 votes
1 answer
424 views

What is an algorithm to find the largest rectangle of white space in an image?

Take an image, (the Google home page) is a good example. I want an algorithm to find the largest white rectangle in this image. That is to say, the largest rectangle that would fit in an area of ...
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3 votes
1 answer
170 views

Applying SVD compression to integral point images

Suppose that we have an $m\times n$ matrix $A$ of rank $n$, whose entries are 8-bit unsigned integers obtained from a grayscale image. Now we want to apply SVD to $A$ and to use the first $k$ singular ...
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1 vote
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What is the best algorithm for detecting the texture of a person's clothes in real-time for a mobile robot?

I am working on the human following robot. the robot extracts a feature of clothes's texture and distinguishes between the people that they stand up in front of the robot. So, the robot needs that it ...
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1 answer
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Greyscale image to binary image conversion using operations on pixel

Previously, I tried convert a color image into a greyscale image by using pixel values of an image from a simple formula :- Grey = 0.3*Red + 0.58*Green + 0.11*Blue ...
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1 vote
2 answers
271 views

An algorithm to find the closest match between 2 arrays of RGB pixel tuples

So I'm looking for a bit of an abstract algorithm and I'd appreciate any references to read up on. This is a bit tough to explain but I'll try my best. Suppose we have 2 arrays of ...
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1 vote
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Image/Video deblurring

I am currently working on an algorithm that will help to improve shaken blurry images. I know there are plenty of them, such as deconvolution, that is pretty useful though I don't really know how to "...
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1 vote
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Why HOG angular bins have values between 0 and 180 degrees?

I have learned that HOG angular bins have values from 0 to 180 since the algorithm uses unsigned gradients. I am failing to understand why. As far as I know gradient orientation is calculated as <...
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Image classification with zero data

Given an image of a biology diagram, I would like to classify the diagram into these 4 categories: Plant Animal Cell Anatomy However, I don't have any training data. I would like to avoid the ...
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2 votes
1 answer
272 views

Image segmentation of a high resolution 2D binary image into clusters, threads and points

I use python3 script to find out the area proportion of pixel clusters, threads and points in my image. They are originally 8-bit greyscale TIFF images with a resolution of 2048x2168 pixels. I have ...
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Gaussian noise: Image Processing

As we all know, Gaussian Noise follows Gaussian or Normal distribution, and that distribution follows a $BELL$ $CURVE$. As we can see that most of the values are centered around the mean. Now ...
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1 vote
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"higher intensity" and "high signal intensity" in images

I'm newbie in Computer Vision and image processing. I'm reading the article "Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR" and it said: 2.2.4. WMH ...
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What is f(x,y) in Digital Image Processing?

I am a novice in Digital Image Processing, and while reading the book of DIP by Gonzalez and Woods, I find that they have represented digital image as $f(x,y)$ but nowhere it is mentioned what is $x$ ...
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5 votes
1 answer
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Hausdorff distance between two binary images according to distance maps

I want to compute the Hausdorff distance between two (very large) binary images X and Y, which is: $$H(X,Y) = \max\left\{\,h(X,Y), h(Y,X)\right\}\!$$ with $$h(X,Y) = \sup_{x \in X} \inf_{y \in Y} d(...
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Tapered Quantization

In Gonzalez et al it is mentioned that Tapered Quantization is I am unable to figure this thing out. I have searched the whole internet, but nothing of the same appears. I need a help in ...
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3 votes
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Partial derivatives of bilinear Sampling

I'm going over the paper Spatial Transformer Networks (link). On section 3.3 they introduce bilinear sampling kernel (Eq. 5) $$ V_{i}^{c}=\sum_{n}^{H} \sum_{m}^{W} U_{n m}^{c} \max \left(0,1-\left|x_{...
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How can i compare lossy image compression techniques?

I need to find which lossy image compression technique is the best. I chose to test JPEG, WebP and BPG. Which criteria can I choose for comparison apart from quality and speed of compression and how ...
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Image quantization for grayscale images with alpha channel

I am looking for algorithm that quantize grayscale image that contains alpha to 4-bits (16 colors). I quite like the effect that is used in IrfanView to decrease color depth, however, I dont know the ...
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1 vote
1 answer
203 views

Fitting a polynomial to a set of points or to a skeleton

Available data Available to me is a set of points which can be represented as shown in image 1: Also available to me is a non-continuous path derived from this data. It is not important how this non-...
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2 votes
0 answers
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Do image artefacts reveal the original image orientation?

An image is taken and then rotated by an arbitrary angle and cropped. Let us assume that the original image is rather meaningless and is not aligned in any way. Given the rotated image, is it ...
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2 votes
1 answer
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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?
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1 answer
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Minimum Bounding Quadrilateral

In an image processing project (using opencv with python), I am trying to detect as precisely as possible the location of a rectangular object in a photograph. My final goal is to output the 4 corners ...
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