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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Target detection for UAV landing

I would like to detect and track the following target to land an UAV. Target size is $1\rm m \times 1\rm m$. I have tried SIFT + FLANN but there is too few keypoints to have a good match. Have ...
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1answer
34 views

How can I learn image processing in a practical way?

I am a beginner in image processing and I have to learn to program in MATLAB as soon as possible. I started with Rafael Gonzalez book, but understanding this theoretical knowledge and mathematical ...
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13 views

How can I use Hermite Kernel as feature extraction?

I'd read about hermite polynomials, hermite filter and hermite kernel which is I'm not sure if all of these are the same thing. I can't understand how these thing can be used in image processing. Is ...
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1answer
42 views

Confusion about adjoint of convolution

I have the following problem with convolution operators. I know that if I have a filter $g$, then the adjoint filter would be given by $h(x,y)=g(-x,-y)$, so that $\langle g * u,v \rangle = \langle u,...
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24 views

How are convolution matrices designed? [closed]

I've been looking deeper into convolution filters for image processing, and I can't seem to find an intuition for how people come up with the matrices that people use. For example, edge detection. I ...
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18 views

Gaussian noise in spectrum image? [closed]

I'm restoring an image and I noted some sort of gaussian noise in the spectrum of the image. I tried an average filter to "kill the noise in the spectrum", but it was a mess. Now, my question is: ...
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0answers
43 views

What transformation (or similarity metric) is rotation, shift, and scale invariant?

I have an algorithm to to detect copy-move forgeries in images. I used block matching to detect regions of an image that were forged with copy-move forgery and highlighted the alleged areas. For block ...
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1answer
31 views

Measuring similarity between two images

I have some images (generated from some processing). Some of those images have approximately the same view of the scene with illumination changes. But there are other images which may show the view ...
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1answer
32 views

Finding the maximum and minimum frequency of a 2D image

Suppose I transform the image into frequency domain and obtain a 2D array of complex numbers. How can I determine the minimum and maximum frequency from that array? By finding magnitude of each ...
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61 views

Save ROI and background in two images

I'm using MATLAB Training Image Labeler app for labeling images and exporting the regions of interest (ROIs) which I save in .jpeg files.The ROIs are exported as a structure $1\times 430$ with two ...
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44 views

Annotate a dataset of images

I'll be recording a new dataset using a couple of sensors: kinect, stereovision cameras.. for a project for people detection using only depth information. But I don't know yet how can I annotate the ...
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2answers
57 views

What is the difference between convolution filter, low-pass filter, and median filter?

Isn't blur filters, like median filter, a type of convolution filter? How does a low-pass filter relate to them? Why does this guy differentiate convolution filters here from blur filters here?
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80 views

Image processing - Is mean filter shift-invariant?

Update: So, according to this article. For a 2D mean filter, $$ H[f(x,y)]=\frac{1}{NM}\sum_{k=0}^{N-1}\sum_{p=0}^{M-1}f(x-k,y-p)=g(x,y)\tag{1} $$ $$ g(x+x_0,y+y_0)=\frac{1}{NM}\sum_{k=0}^{N-1}\sum_{p=...
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1answer
22 views

Smoothed image produces contour-like ripples, yet it disappears in saved image?

I smoothed a grayscale image using a size 10 gaussian filter and display it in Octave (imshow) which resulted in ripples which appears to be contours for image intensity. Yet if I save the image (...
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2answers
58 views

How can I implement convolution in frequency domain?

Suppose, we have a bitmap image represented as a 2D integer array, int [,] image2D; whose FFT is Complex[,] fftImage2D; ...
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2answers
112 views

How can I construct a Band-pass filter from a low and a high-pass filter?

Suppose, I need to construct a Band-pass filter in OpenCV. But, I know, there are no functions in OpenCV for Band-pass filters. Now, what I need to do is to have a low-pass filter and a high-pass ...
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1answer
26 views

What is an 'Oriented' Band-pass Filter?

In this research paper, Section 4.1 talks about a filter called "Oriented Band-pass Filter". What does it actually mean by 'Orientation'? Also, the article gives a function, $$H(u, v) = \frac{1}{1 +...
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0answers
31 views

Is there a way to detect ambiguous edges?

I'm writing a program that can detect veins(the dark lines) on an arm. When looking at the image at full size, you can easily make out where they are. But when zoomed in around a vein I get ...
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0answers
10 views

What does a Sobel Norm of an image represent?

Why would we want to find the Sobel Norm of an image?
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25 views

How to extract 2D image points from an RGB image?

My approach is to implement Depth Image Based Rendering algorithm. The first part of the algorithm is, m1 = A1*P*M and ...
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0answers
16 views

Comparison of learned basis functions from neural nets and the human visual system

In the talk linked below Andrew Ng states that neuroscientists have performed a quantitative comparison between the basis functions learned from sparse coding and those that appear in the primary ...
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0answers
14 views

Skin-based face detection

I am trying to develop a skin color-based face detection program and from what I have read so far (in the research papers),this is what I have understood: The aim is to classify any pixel as 'skin' ...
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1answer
46 views

Blind source separation on images - with a known source

A camera outputs an image $A$ that is a linear combination of two uncorrelated images $B$ and $C$: $$A = B + kC$$ Images $A$ and $C$ are known; the unknowns here are $B$ and a scalar coefficient $k$ ...
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1answer
49 views

Calculate sum of absolute difference per pixel

I am trying to implement a research paper just to verify my results. I have shared the code (written by me) and the description of the process given in the research paper. Unfortunately my results are ...
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2answers
23 views

How to discover an image clone

I have an image depicting a results of gel electrophoresis (it does not really matter - it just means: no bodies, faces, predictible objects) and I have a strong suspicion that a part of the image ...
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13 views

How to use Mikolajczyk evaluation for detectors/descriptors?

I want to compare different detectors/descriptors (both binaries and not) for my application and I want to use the Mikolajczyk evaluation framework, which is became a standard in the community about ...
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20 views

Finding SIFT keypoints on a plain surface

I am using SIFT for object recognition and tracking. The target object is metallic body which is painted with a single colour paint. There object is plain.(Consider something like a metallic plate ...
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1answer
125 views

How can I construct a frequency domain Bandpass filter in OpenCV? [closed]

I am working on a Scratch Detection project on the basis of a research paper "Multidirectional Scratch Detection & Restoration in Digital Old Images". I need to implement the paper in C#. Does ...
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1answer
23 views

How many types of Bandpass filters are there for image processing?

This article shows that: Ideal Bandpass filter Butterworth Bandpass filter Gaussian Bandpass filter Is that classification correct? Are there any other types?
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1answer
32 views

What is Local Mean Filter?

The research paper "Multidirectional Scratch Detection and Restoration in Digitized Old Images" says that, 4.1. Preprocessing. The preprocessing step aims to enhance image features along a set of ...
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32 views

Blister detection using image processing

I am faced with the task of automatically detecting blisters in industrial gloves. Please see the images below for some positive examples (i.e. images with blisters): We need to detect blister ...
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2answers
41 views

Generate 3D image from multiple 2D images

If we're to capture an image of a body using four (4) WebCam with a 16 megapixel (1 in the front, 1 in the back and 2 sides(left and right)). Is it possible to make a 3D out of it using image ...
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11 views

What are various types of Gabor Filters?

Gabor Filter has 4 types of kernels: Real Imaginary Complex Magnitude Squared Magnitude What do they actually mean? NB. Please, supply me any resource for further study.
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1answer
31 views

Soft question: Seeking compressive sensing imaging demo in MATLAB

I am looking to experiment in MATLAB with image restoration/reconstruction using compressed sensing. I am relatively new to compressive sensing, and was inspired by the following Wired article to ...
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1answer
46 views

Difference between $\tt rand()$ and $\tt randn()$ in MATLAB [closed]

rand() is for "Uniformly distributed pseudorandom numbers" I generate two rand arrays, and then use the cross-correlation (<...
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0answers
18 views

Projector image subtraction

Imagine you have a projector and camera pointed at a wall, with people walking in front of the wall (between projector and wall). Is there a standard way to robustly obtain silhouettes of the people ...
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3answers
59 views

Where and how do an Image and a complex number meet?

I am trying to implement a Gabor Filter bank. Gabor Filter uses a complex function. How do the filters like Gabor Filter operate on an Image? Does a complex number represent an entire Image or only ...
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1answer
26 views

Poster detection in OpenCV?

I'm really new in image processing, so please sorry I'm a newbie. I tried to use the squares.cpp for detecting posters (since they usually are rectangles) without using expensive feature detectors (...
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0answers
20 views

Hyperspectral vs Multispectral Imaging

I understand that the difference between the two are the number and width of the bands. Given a hyperspectral image, is it possible to 'convert' it to multispectral ? In this paper for example, the ...
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0answers
33 views

What is the Center Frequency of Gabor Filter?

If the standard form of a Gabor function is as follows, $$ g_{\lambda, \theta,\varphi, \sigma,\gamma}(x, y)=\exp\left(-\frac{x'^2+\gamma^2y'^2}{2\sigma^2}\right)\cos\left(2\pi\frac{x'}{\lambda}+\...
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13 views

Image retrieval approach

I have a good understanding of 'normal' Machine Learning, I'm pretty good at Python and have decided to start a Raspberry Pi project, however my knowledge of Image Retrieval is limited. I'm trying to ...
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2answers
20 views

How to calculate to structure tensor?

Structure Tensor is a matrix in form: $S=\begin{pmatrix} W \ast I_x^2 & W \ast (I_xI_y)\\ W \ast (I_xI_y) & W \ast I_y^2 \end{pmatrix}$ where $W$ is a smoothing kernel (e.g a Gaussian kernel)...
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1answer
24 views

Global vector descriptor

Usually, algorithms as SIFT, SURF and many others provides a set of $k$ keypoints and the associated descriptor in $d$ dimensions (for example, in SIFT each descriptor has $d$=128 dimensions). So, in ...
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2answers
39 views

Estimate/Compute parameters of image dataset

I have a dataset of images taken by Kinect (RGB and D) How can I extract the following information only from the images: Frame rate Camera height The dataset containes images of person (s) moving ...
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1answer
47 views

Count the vehicles flow that pass over one bridge

I live in an apartment near a bridge. From my window I can see the cars traveling over the bridge as you can see below: Is there a relatively simple manner to count each car pass over the bridge? ...
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0answers
19 views

object selection from an image using watershed

I have already done the thresholding and skeletonising that image for the separation of the fiber.How to separate a fiber from a group of fibers and to find out the length and other properties of that ...
4
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1answer
52 views

Detecting sloppy hand-drawn arrows in images

How can I easily and efficiently detect hand-drawn arrows and their directions from an image? They're probably drawn lightly, with something like a pencil, on a piece of paper. If I had ...
2
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1answer
26 views

Difference between texture and illumination in image

I am new in image processing. What are texture and illumination in image? How can we define these terms?
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1answer
34 views

DWT architecture using filter bank

I am studying this paper. In one of the figures in the paper (Fig 5.b and Fig 5.c) DWT architecture is given using db2 and filter bank. I don't understand how Lo_D and Hi_D have size half of input ...