In general, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame.

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2D Haar Transform Computational Complexity

I want to learn the computational complexity of the 2D Discrete Haar (Wavelet) Transform (DHWT). The number of operations (divisions, summations etc.) is the main focus. I think there many different ...
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53 views

How to prove $\int_{\Omega} \sum_{i=1}^{N} f_i(x)dx$ is equivilant with $\sum_{i=1}^{N} \int_{\Omega} f_i(x)u_i(x)dx$

I have a 2D image defined on a region $\Omega$. Assume that the region can be separated into $N$ sub-regions $\Omega_i$ such that $$\forall i,j=1... N:\Omega_i \cap\Omega_j=\emptyset$$ and ...
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10 views

To estimate the uncertainty of Slicing holes from an image?

I am thinking to estimate the uncertainty of holes photographed from the bottom and top side. The difference of the same hole photographed from two sides is distributed as Gaussian. The length of ...
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16 views

Understanding Eigenface Face Recognition Algorithm Notations

I have been reading the paper from Matthew A. Tusk and Alex Pentland https://www.cs.ucsb.edu/~mturk/Papers/mturk-CVPR91.pdf I got stuck in this part. I have a couple of questions. Assume my ...
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21 views

Object detection algorithm

I need detect object in series of pictures. This object has something like nonsymetric relief structure with some irregularities. In this conditions. Light conditions can change from almost dark to ...
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8 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 ...
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39 views

How to extract text from a scanned document?

The task I am facing is extraction of rotated text (any angle) from a scanned image(attached Image). The image contains a blue sticker on it and need means in extracting the text (printed text) from ...
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22 views

How to calculate performance of your object recognition algorithm and compare results with others?

I am working on a novel object recognition algorithm with BoF implementation for my MSc project and it performs fairly well. I am using it on Caltech101 dataset. I want to compare the results with ...
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24 views

How to gather similar objects in an image?

I am working in a traffic tracking app, I am using a background subtraction approach to obtain information about the moving vehicles. After some morphological operations I obtain blobs of the moving ...
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58 views

What is the image power law?

What exactly is the image power law mentioned at page 15 in here: Is it related to Gamma correction or the statistical power law ?
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21 views

intensity scaling: precise definition?

I am a little confused about definition of intensity scaling. It is something like histogram equalization or a method in which we just multiply all intensities by a scalar. Thanks
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25 views

Estimating the variance of noise using median function (?)

By investigating the implemented code of an accepted paper, I encounter with following relation to estimate the variance of noise in an image: $$ \sigma = \frac{median ...
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26 views

filter coefficients to know high pass and low pass filter

Looked on few questions already there in dsp.stackexchange and couldn't get the direct answer. Basically I have a kernel of a gaussian separable filter. float w[N*2+1] = {-0.00467444956f, ...
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8 views

Compute the Gibbs energy for second-order neighborhood

I have a question about Gibbs distribution in Stochastic theory. In which, it defined a clique as a a subset $C$ in the whole image $\Omega$ if two different element of $C$ are neighbors. Figure 2 ...
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1answer
61 views

Why is C++ so popular for Image Processing? [closed]

I have been a student of Image Processing for 3 years now and have been using C++ as the programming language to implement different Image processing operations. But I don't really why in particular ...
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17 views

Image processing usign conv-neural net

Okay I am starting to understand the idea of neural networks but I still haven't been able to understand the use/benefits/implementation of convolutional neural networks especially for image ...
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6 views

The interpolation formula for building a steerable 3D filter of a second-order Gaussian

I am trying to write the Matlab code for a steerable 3D function, but cannot find anywhere the interpolation formula between the spherical harmonics. I researched on the internet, but really didn't ...
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29 views

Four different types of third order image moments (skewness), what are the differences?

I am attempting to analyze images using the third order image moment (aka skewness), but I am having trouble figuring out how to do so. As it turns out, there are four different types of third order ...
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25 views

SSD for RGB images

To compare grayscale images, I'm using SSD like the difference between the two corresponding pixels and then choose the minimum. But when it comes to RGB images, how should it works ?
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21 views

How do I compute the gradient vector of pixels in an image?

I'm trying to find the curvature of the features in an image and I was advised to calculate the gradient vector of pixels. So if the matrix below are the values from a grayscale image, how would I go ...
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9 views

What I am doing wrong when applying constrast sensivity function?

Physics explanation I am filtering an optotype image in order to simulate how a human eye would see it. I am not taking into account aberrations but only diffraction. The problem is that my ...
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4 views

SIFT: Finding unstable and stable intervals in interval tree

I try to understand SIFT. I have watched a couple of videos but still cannot catch the point that how we can mark an interval 'unstable'. What is exactly the definition of 'stable'? According to ...
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5 views

Comparing the spatial frequency between groups of images

I have 2 groups of images, and I want to compare these groups based on the spatial frequencies of the images. In the end, I'd like to be able to say "group A is/is not significantly different from ...
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1answer
23 views

Detecting a smooth boundary with known shape in an image

I have designed a surface with a shape like a rounded rectangle and I want to detect its exact boundaries in a photo I take from it. A sample photo is like this: I have tried thresholding the image ...
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33 views

SIFT: why it is invariant to affine tranlsation?

I am studying SIFT. I am a little confused in some of Lowe's algorithm. In order to have a descriptor invariant to translations like scaling, we must get rid of the scaling factor in LoG (Laplacian ...
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47 views

how to match 2 signals that have same information, though shifted and scaled

I have 2 signals S1 and S2 that contain the same information, but S2 is shifted and scaled compared to S1 by an unknown amount (but small; eg shift would be of the order of 1-10 samples). What is the ...
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92 views

I am looking for the concept about all-in-one curve fitting

I know that there are some Technic for finding curve fitting like polyfit() or pinv(). so we can get a some polynomial equation. it's OK good. I can get successively a polynomial equation for each ...
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36 views

why the sum of masks should be one?

I am studying pyramids (expanding and reducing) and I am a newbie. Why sum of the convolution mask should be one when we are using Gaussian distribution? According to When should the sum of all ...
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21 views

eliminating white areas without sharp boundaries

I have images of following type: and As one can see, in the corners of the images there are white areas which don't have sharp or well defined boundaries; the intensity gradually decreases. ...
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6 views

What is the difference between 2D and 3D brain tumor segmentation in MRI images?

are we using jpeg images for 2D and DICOM images for 3D segmentation? what are the algorithms used efficiently for 3D medical image segmentation
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3answers
45 views

Even and Odd Filters and Quadrature

I am a mathematician trying to understand some signal processing terms. My first question regards the terms 'even' and 'odd' filters. What does this mean? Does it reference the fact that upon a ...
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29 views

neural network for 3D pictures

I'm wondering if they are some state-of-art algorithms to apply the convolutional neural network approach to 3D pictures, eg. input is no longer a grid of pixels, but voxels. My objective is to ...
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1answer
24 views

How to apply a 1D filter (CSF) to an image?

I am facing the following problem: I have an image and a contrast sentivity function (CSF). The CSF is a function defined in the frequency domain and it is just a band-pass filter. The problem is that ...
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24 views

Removing DC offset and ensuring zero-sum for 2D filter

I'm working on project where I'm using Independent Components Analysis (ICA) on NxN patches from images to separate components in an image signal. Each column of the resulting MxN^2 unmixing matrix is ...
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42 views

Help Understanding the Robert Cross Operator

I have been reading this Wikipedia article: https://en.wikipedia.org/wiki/Roberts_cross And it says this: Now I have also been reading this for the Robert Cross operator (from Feature Extraction ...
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1answer
25 views

Which anatomical model to use as “ground truth” for validating an MRI segmentation method?

I am research in brain segmentation task that classify a brain in to 3 classes : White Matter, Gray Matter and CSF. To validate my method, I used Dice Coefficient that compare my result and ground ...
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14 views

Getting image intersection area perentage

i have two flying robot. And they are flying at same height (nearly) and they are looking same direction and pose. Both of them have same camera and the cameras looking to floor. When the robots are ...
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48 views

How to use wavelet decomposition for feature extraction (of fMRI images)?

I have a dataset consisting of fMRI images (from mice) which are divided into 4 groups (different drug dose levels applied). Each fMRI image is 4D, that means each voxel is a time series. For each ...
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1answer
37 views

Invariances in Neural Networks

I have a question about invariances in neural networks. In general, neural nets with enough layers can learn arbitrarily complicated nonlinear functions. Therefore, it's not hard to understand how ...
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19 views

Correlation of an image in the Fourier Domain

I have been reading up on correlation in the frequency domain, and I just had two questions which I could not find in the book I was reading nor online: [1] So correlation is the same as a normalized ...
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12 views

Matlab fspecial disk: Algorithm reference or algorithm logic

I'm trying to figure out how the fspecial function works to create a discrete disk in Matlab. This function is an averaging filter that arises in an image processing environment. The Matlab algorithm ...
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71 views

Translation invariance in max-pooling and cascading with convolutional layer

I am reading through this page about convolutional neural networks and I am confused about the part about max-pooling (downsampling a signal/image with the maximum value in a block). Apparently, one ...
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5 views

Is the same to calculate the Moments of an image using only its vertex?

The below image is a convex filled polygon, to calculate its moments we can resort to the Hu Moments and if the image is very big, this could be an expensive process. But if we use only the vertex can ...
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46 views

How to detect those areas which are lightened up

I have two images of a scene, IA and IF (this is not no-flash and flash image case). They can be thought of as two binary masks. Image IA: Image IF: If you observe closely, there is a change ...
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5 views

How can you test Gamma in ISP for test?

In CMOS image sensor, there are gamma processing block in the so many ISP chains. Is there any one know how to test the gamma block only whether working good or something wrong? How can you test ? Is ...
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1answer
55 views

Estimating an image filter from examples

I am sure this question must be fairly easy and could have been answered on this site but perhaps I am not finding the right keywords to search for it. I would like to know what are the common ...
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3answers
94 views

why the ultasound image is noisy by speckle noise?

My first question : I want to know why an image is noisy ?. why the ultrasound, SAR and Laser... images are noisy by a multiplicative noise not an additive noise? Another question : So the ...
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28 views

Remove noise from Binary image, License Plate noise removal (MATLAB)

How can I remove noise form Binary license plate? example images: http://s1.upload7.ir/downloads/XB6RfCQnJz5dyJgXPrg2Co5OmAFSkmO8/Untitled.png source file : ...
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83 views

Distances In a Single Image With Some Real References

Consider following image: We have some real references here: Stonehenge measurements (stone dimensions and distances), some strait lines at the back of carts, cart wheels that are almost of the ...
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12 views

Where can I find images corrupted by periodic/coherent noise?

I found one here https://scipy-lectures.github.io/_images/moonlanding.png I would be more interested in photographs which are naturally corrupted by such noise. I am seeking them in order to use ...