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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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
11 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 ...
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1answer
19 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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1answer
19 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
38 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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14 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 ...
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1answer
41 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 ...
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1answer
21 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
20 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 ...
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9 views

Drawing boxes where features in image are marked by contours

I am trying to draw boxes to surround features in images, however, I have obtained very weird results but I am not sure what has happened. The image in the window titled "drawing" is the image after ...
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25 views

Where to start learning about image quality testing for smartphone? [closed]

I am going to start working as a trainee in image quality in a smart phone company. I have basic knowledge in overall image processing, but now want to be specialized on image quality only, but cannot ...
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13 views

How to remove noise from this image without causing the crack to 'shrink'?

I am currently embarking on an image processing project to detect cracks on surfaces using OpenCV and Visual Studio via C++. I have tried writing my program and at the moment, I am stuck because I ...
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1answer
22 views

Connecting segmented region in image

I am working on segmenting hands from monocular images and I have already come up with a pretty descent segmentation. The only issues I am having are when people have rings on their finger. Then the ...
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1answer
39 views

What is an Image Prior?

I am having trouble in understanding the concept of image-priors. What is it exactly? What is the advantage of using them? Where are they used?
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17 views

Detecting objects in real world video feed?

I have an image which consists on an object in a plain black background. This is the reference image of the object. Now, My task is to take a webcam and obtain the video feed and I have to detect if ...
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0answers
19 views

How to calculate standard deviation of the pixels in the picture? [closed]

I want to calculate the color values of the pixels in order to find the standard deviation of the colour uniformity. The picture is taken with camera of full black pattern shown on a led tv. But the ...
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1answer
47 views

2-D Digital Signal Processing

I have been doing my research on 2D digital signal processing. What I am doing is about noise removal of digital image: Type of noise that I want to remove from an images is like the Gaussian noise ...
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0answers
10 views

looking for simplified version of motion capture for simplified situation where objects are solid and have no joint (no internal degree of freedom)

The whole question is about a simplified algorithm for tracking a single solid object which has no joint, with assumption that i have full control on adding some markers in real world to it. For ...
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31 views

How do image resampling in Matlab for panorama stitching?

I am working on Panorama stitching problem (Typically, I follow this pdf: http://newton.uam.mx/xgeorge/uea/graficacionII/Lab4/lab4.pdf) I have implemented everything, and get the homography matrix, ...
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1answer
26 views

What is the value of the standard deviation $\sigma$? [closed]

I am using the following formula to add the additive Gaussian noise. noise= (x/255)*(randn(size(image))), where x is the ...
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0answers
10 views

Is there an optimal range for Pratt's Figure of merit?

I am working on a new edge detection method. However, when I tried to evaluate it based of FOM values, I got really small values, though my algorithm's performance is good comparatively. What I ...
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0answers
18 views

circle or arc recognition in noisy image

I have an image that is missing the center and contain what seems to be two parts of circles or maybe two arcs. What is a good metric or signal processing approach to use to differentiate between the ...
13
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2answers
639 views

Why real part of FFT converts image into rotation + original?

I have read this image: taken its FFT (2D) and then Inverse FFT to get exactly the image back. Code is provided for reference: ...
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1answer
23 views

pixels in the same image are correlated but how can I visualize it?

I am new in image processing.I know that pixels in the same image are correlated with each other but I don't know how can I draw the relationship b/w these pixels in the form of graph?.
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13 views

Decompose an N x N 2D DCT into 4 N/2 DCT's

I have a fast implementation of a 16x16 DCT and IDCT in c++, I would like to know how to partition a 32 x 32 array of values and scale factors to implement a 32 x 32 DCT, and IDCT respectively. A ...
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18 views

what is the differences between thin structures and edges in image

I want to know what are the differences between the thin structures (filaments, point, segments) and edges of image. How to detect the fine structure. why the Bi-Laplace operator can detect the ...
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35 views

Why pixels on image edges are shifted when using Wiener filter?

I implemented a Wiener filter using Matlab and i noticed that both functions(mine and matlabs) are creating an image with shifted pixels on the edges. Class teacher said it will happen. Is there a ...
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2answers
82 views

Identifying license plate number of a thief's car from a video

Motivation: I recently had my laptop stolen, with lots of pictures of my family, research work and other very important stuff. Of course the theft has been reported, but I think people here are more ...
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1answer
22 views

Removal of blocking artifacts in images due to compression

Having compressed an image,how can the compression noise or blocking artifacts be suppressed to improve the quality of the image before further processing. Thanks
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2answers
69 views

How can this equation hold $$\sum_{m=0}^{N-1} \sum_{n=0}^{N-1} |u(m,n)|^2 = \sum_{k=0}^{N-1}\sum_{l=0}^{N-1} |v(k,l)|^2$$?

I am trying to learn digital Image processing by myself and now stuck at a problem in the two dimensional unitary transformations. It states that let $U$ be the input image and $V$ be the transformed ...
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2answers
43 views

sparse representation for image denoising

When I read papers on image denoising, I always encounter sparse representation. For image denoising, we try to separate image signal from noise. It is assumed that signal is correlated and noise is ...
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1answer
88 views

Subsampling property of wavelet transform

One of the properties I have seen for isotropic tight wavelet frames is $$\sum_{i\in\mathbb{Z}} \left|h(2^i\omega)\right|^2 = 1$$ where $h(\omega)$ is the frequency spectrum of the original wavelet. ...
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1answer
64 views

Geometric explanation of a methodology in the article about Image Denoising

In article Ghimpeteanu G., et al. - A Decomposition Framework for Image Denoising Algorithms, I found as below: Let $\displaystyle I : \Omega \subset \mathbb{R}^2\mapsto \mathbb{R}$ be a ...
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14 views

Traditional Active Contour - Negative alpha

Would it be possible to set alpha to negative so the contour would expand instead of shrinking ? I have tried searching on google but it seems like there is no discussion on it. Seems like alpha is ...
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13 views

What is the gold standard for vehicle headlight detection during night?

I was wondering which current approaches exist for vehicle headlight detection during night. I've found a couple of recent approaches, but I'm wondering if there is a gold standard for this kind of ...
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0answers
25 views

Python cv2 Image Pyramids

Trying to implement the famous Orange/Apple pyramids blending (cv2 Image Pyramids). Note: Both images shape is 307x307. However, since the result image is blurred due to clipping values in ...
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0answers
10 views

Traditional active contour

I am reading on up active contours for my assignment and I have some questions regarding the energy formulation of the active contour. $E = \int \frac{\alpha(s)|v_s|^2 \ + \ \beta(s)|v_{ss}|^2 + \ ...
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1answer
52 views

Accurate Image Resizing

I need to resize an image using bilinear interpolation and create an image pyramid. I will detect corners at the different levels of the pyramid and scale the pixel co-ordinates so that they are ...
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3answers
81 views

What do Skewness and Kurtosis represent?

I understand that the question could mean a lot of things but I am thinking specifically to image processing. For example, I know that the mean can be a basic texture feature that represents the ...
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0answers
14 views

Analytical expression for salient Blob detection in scale space

I am working on exact mathematical expression which can be obtained in image processing tasks.(I do not know much about image processing but my work is more mathmatical) In Gaussian scale space, we ...
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1answer
45 views

Object detection in binary image

This task comes from tracking object on a steady background. So far I was able to remove the background and obtain binary masks like this: I need to get bounding rectangle of the toy without the ...
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1answer
26 views

How to set threshold value for Hough Transform

I am new to Computer Vision, I am writing my own code for Hough Transform I have found the following algorithm: Algorithm: ...
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3answers
49 views

Replace phases of image FFT

I have 2 images of the same scene, captured by different cameras. So they a bit displaced. As far as I can understood, phases of FFT contains info about image details. My goal is to take intensity ...
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1answer
70 views

How to understand the implementation codes in Debevec and Malik's HDR paper

The paper titled "Reconvering High Dynamic Range Radiance Maps from Photographs" from Debevec and Malik is a seminal paper in high dynamic imaging. In this paper, it proposed a method to estimate the ...
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14 views

Edges in Content Based Image Retrieval (Java)

I have developed a programme that currently computes the standard deviation. I am trying to alter this algorithm so that it can extract the edges of an image. I have been told I can do so if I build ...
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1answer
60 views

Which is correct representation for function of variable?

I have a function as $$E=\int_\Omega -\log\big( p_i(x)\big) dx$$ where $p_i(x)$ is density distribution which estimated by Parzen window method. $$p_i(x)=\frac{1}{\Omega_i} ...
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25 views

Is it possible to rewrite gradient magnitude of Sobel in continuous formula?

Let $*$ denote a convolution operation, $G$ denote a kernel, and $I$ is a given image. The gradient of the image $I$ is equivalent: $\nabla (G*I) = (\nabla G) * I$ The Sobel filter approximtes two ...
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2answers
69 views

Segmentation of small artifacts - Image Processing

I am working on a task of segmenting small artifacts from a set of images like below: I am looking for a generic approach, but unsure of what to search? I tried looking at density flow analysis, but ...
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4answers
59 views

What is the difference between the terms color Intensity and color Saturation?

In Digital Image Processing, what is the difference between the intensity and the saturation of a color? How would you explain the difference to a newbie?
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82 views

Removing noise from dental radiography

I'm working on a project of applying Active Shape Model to locate tooth in dental radiograph. For those familiar with the technique, I'm currently trying to sample along normal vectors for each ...