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Questions tagged [image-processing]

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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How to detach overlapping contours but not to remove small ones. Alternative to erosion-dilation cycle

Background: I'm trying to detect trees on a sequence of aerial images by calculating a stereo disparity for consequent pairs of images. This is how disparity looks like. White spots are trees: Next, ...
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39 views

How to recognize for small video sequence with a large sequence?

I'm working on the idea of recognizing a small video sequence (a sequence of 18 seconds) within a long one (a sequence of 15 minutes), the first idea that come to mind stats that I have to ...
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71 views

Image Histogram - What Is the Interpretation of PDF

For digital images (assume 2D gray scale image), the normalised intensity histogram is often treated as the probability distribution function of the intensity ie., intensity is treated as a random ...
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205 views

How do steerable pyramids work?

I'm reading a paper about texture synthesis using pyramids, and the very first section mention two methods for constructing pyramids, one is the Laplacian Pyramid (which I'm quite familiar with), the ...
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58 views

Given the 4 corners of two QR codes on a photographed sheet of paper, can we get a deskewed rectangular image?

I made a photo of 2 sheets of paper with a phone camera, each of them cropped at the: (x1, y1) top left corner of top QR code (x2, y2) bottom right corner of bottom QR code I hoped that the x, y ...
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21 views

Linear Predictive Coding in Gray Scale Image

I was trying make linear predictive code in gray scale image and want to find first 5 correlation values where the grayscale pixels are: [$S_2$][$S_3$][$S_4$] [$S_1$][$S_0$][$blank$] And i want to ...
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234 views

removing vertical lines in grayscale images by thickness

Suppose we have a grayscale image that contains vertical lines. Now suppose that not all vertical lines are the same, some of them have different thickness. Question is, is there a way, in MATLAB or ...
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648 views

How to remove lines from captcha image which are acting as noise using java?

The images are attached here. I first converted the sample image to grayscale and then binarized it. Finally i applied median filter to remove the dots from the image. However i am unable to remove ...
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Does Gamma Correction Interfere with Sub Pixel Motion Estimation?

Advanced Video Coding (AVC) and High Efficiency Video Coding (HEVC) work on gamma corrected, non linear, colors. When interpolating the value at subpixels, a multi tap algorithm processes the gamma ...
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27 views

Estimating a matrix from another matrix

The problem is the non- negative matrix factorization of a matrix. Let me explain my problem I have an original matrix $A=\begin{bmatrix} 0.248437 &0.25198098 & 0.25396825 & 0.25077881\\ 0....
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71 views

How to find Performance Ratio (PR)?

If we have one image from BSD (The Berkeley Segmentation Dataset and Benchmark) and for this images Ground truth, how to calculate PR? PR is the ratio of true to false edges and can be calculated by ...
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53 views

2D - FFT using Xilinx System Generator

I have searched the 2D-FFT implementation using 1D-FFT. Is there a reference design for 2D-FFT implementation in the System Generator of Xilinx ? Espeacially effectively use of FPGA resources. i.e : ...
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92 views

Skewed rectified aerial images

I have a series of aerial images from which I would like to get disparity maps for every consequent pair. In order to do that I do a stereo rectification. The problem is that sometimes rectified ...
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1answer
33 views

what is adaptive compressive sampling?

I have just started my work in compressive sensing. the measurement vectors are obtain by multiplying the sensing matrix with input signal. the thing i cant figure out adaptive compressive sampling. ...
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1answer
31 views

Need a 2 parameter ranking system for image compression

I'm working on a project in which specific bit planes of an image are extracted and compressed. This process is repeated for every combination of bit planes possible.For an image, I have calculated ...
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101 views

Finding the Best Gaussian Smoothing Kernel to Minimize the Discrepancy Between Two Images

Suppose we have two grayscale images, $A$ and $B$. $A$ and $B$ very strongly resemble each other, such that the mean of the absolute difference $\lvert A - B\rvert$ is fairly small. Suppose further ...
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899 views

How does nearest neighbour, bilinear and cubic interpolation work in images?

More math is appreciated for each of the methods and references are appreciated. I have tried understanding from Wiki and matlab link but don't understand how the translation matrix is being used ...
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47 views

What information does the abs(normalized_image - normalized_quantised_image) carry?

Given a grayscale image X2 And its (under)quantised version with 3 bits depth X3 What information does the abs(X2_normalized - X3_normalized) carry?As an example ...
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22 views

Segment a shape in blobs

I have shapes that look as follow (binary mask): On these shapes, I would like to isolate the "blobs" (and therefore also get the straight segments that connect them). For examples this is the result ...
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1answer
258 views

What is the application difference between extent and solidity in image processing?

I've come across the image object properties, "extent" and "solidity." Definitions are pretty straightforward to understand: Extent of an image object is defined as area of the image object divided ...
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32 views

Difference between camera calibration techniques

I'm confused about the different kinds of camera calibration techniques, what each is trying to accomplish, and what makes them different. I've only ever used ...
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1answer
90 views

temporal high-pass filtering to approximate phase derivative

I am currently following the algorithm as based on a previously published research article "A Motion Detection Algorithm Using Local Phase Information" by Lazar et al. The basic overview of the ...
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1answer
91 views

Redistributing Color in a RGB Image According to a Gaussian Distribution

I haven't done this stuff in a while. If I have an image $I$ I can equalize the histogram of the image using some opencv procedure, it's already defined. Equalizing an histogram means essentially to ...
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2answers
77 views

Do JPEG formats add significant overhead?

For an extreme example, I have the following image that was a JPEG before stackexchange converted it to a PNG:- Before you perform all sorts of funky image processing tricks on it, it's just a black ...
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1answer
53 views

changing circular shift in hologram reconstruction

I'm trying to write a very simple code for the reconstruction of an in-line hologram of particles in a micro channel (digital holographic microscopy), but I'm getting some results that are hard for me ...
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1answer
78 views

Fast empty page detection

As part of a duplex scanning pipeline I need to detect empty pages such that they can be excluded from the OCR and the resulting PDF document. Currently, I'm using a 'blurry' trim which works pretty ...
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1answer
60 views

Help with deconvolving photon reads distributed across neighboring pixels

I'm building a radiation detector that collects photons in CCD pixels and we can relate the energy of the photon from the intensity of the pixel. To test the detector, I took the following spectrum of ...
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2answers
416 views

Fitting a gaussian image using opencv

I'm reading through the opencv documentation and some questions in SO but it doesn't seem to provide this information. I've an image $I(x,y)$ and I want to find a gaussian function $f_{\mu,\Sigma}(x,...
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15 views

Quantization of Image which have taken from partially less dark

I have picture with high resolution with 20M memory space and this image has been taken from the standing away from the window in room which has significantly less light as compared to outside. Image ...
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148 views

FFT Data loss during IFFT

I am working on image encryption using FFT mask. (not fractional) For the start, I applied a series of pseudorandom phase masks to the results of FFT (512*512 elements). (used logistic map for random ...
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2answers
38 views

Evaluate image symmetry

I am trying to evaluate the symmetry of an image with Matlab. My approach is far is based on: convert image to BW get 2D gaussian from the BW pixel cloud get center and axis rotate to get horizontal ...
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1answer
66 views

Algorithm/Code for finding surface shape of an image?

Is it possible to find the surface shape of an image as mentioned in the reference question ? If I find the unknowns of the equation , then what should be my next step in determining the shape of the ...
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56 views

Avarege of a photo and its brightness

Assuming we have a blur image, $I$ , and by using a filter $f$, we get an improved image $I_1$ , the action for doing so is of course : $I_1=f \star I$ While $f$ is the following filter: $$f = \...
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81 views

What do we call the areas with “1” in a binary image [closed]

I am looking for possible professional terms. In a binary (1 or 0) image, normally, the areas with "1"s are where the information is. I wonder if there is any professional name for it in image ...
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15 views

Implementing Wavelet family matrices

I want to use CS to reconstruct an image from fewer samples, and I would like to use wavelet coefficients but I don't know how to define them when making a Psi matrix. I have written wavelets ...
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54 views

Double Threshold Mechanism

I was studying an article about optical music recognition. Somewhere in segmentation section is mentioned that The final step consists of isolating the note heads. This is performed by using a ...
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39 views

How to detect particles having random size and shape?

The task is to be able to detect particles in an empty glass bottle having size and shape ranging from that of a grain of sand to that of a fragment of paper. I have tried a few things, namely: ...
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32 views

Image Classification with CNN

I'm going to use a Convolutional Neural Network to classify images into two classes as re-sampled or not. I need a large data set of resampled and non- resampled images this task. Could you please ...
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1answer
57 views

Suggest an image segmentation technique to find the paste radii?

I am new to MATLAB/Digital Image Processing. So pardon me for any typing errors or wrong use of jargon. 1) I am trying to find the paste diameters for a total of 100 images in sequence. I am posting ...
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1answer
903 views

10 bit pixels convert to RGB

I have a camera which is providing me raw, binary data with 10 bit data. It follows the Bayer pattern RGGB, and each pixel is saved using 16 bit chunks. I am able to demosaic the image almost ...
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6 views

Help with modeling 1-dimensional pixel profiles to test for a significant difference

I am trying to compute whether two fluorescence profiles are significantly different from each other (say between treatment 1 and treatment 2). For computing the profiles, I simply measure multiple ...
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15 views

Signal processing methods for identification of multimedia descriptors for feature extraction (semantics)

It is said in https://www.amazon.co.uk/Multimedia-Semantics-Metadata-Analysis-Interaction-ebook/dp/B005E8AG66 that While there has been a lot of work in the signal processing research community ...
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27 views

Issue in template matching code

code is supposed to take the input image, extract the objects, then overlap circle masks of decreasing radius (r=64,.....1) on each object. A histogram of the no. of white pixels that coincide with ...
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42 views

Scan an Auditorium, Count People, and Display Open Seats

I'm looking for any recommended approaches to be able to digitally process a room full people, like an auditorium or a movie theater and output the following information: Goals: How many people are ...
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2answers
420 views

Image Restoration using kalman filter

I have been trying to restore an image that was blurred with a known Point Spreading Function and corrupted with noise using a kalman filter. I have looked at theory and have a basic understanding of ...
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1answer
93 views

Designing an efficient curve-matching algorithm

I'm currently designing a curve-matching algorithm and as I already explored many ideas I'm requesting your help. So, if you got some advices about how to handle this problem, feel free to answer! ...
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21 views

Doubt regarding definition of pixel bond

The following is a quotation from an Image processing textbook: The connectivity relationship between a center pixel and its eight neighbors can be quantified by the concept of a pixel bond, the sum ...
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36 views

non-eccentricity pattern noise

non-eccentricity pattern noise is a noise distortion applied to images, used in TID2013. I would like to know what "eccentricity" and "non-eccentricity" means in this context. Thank you.
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Regarding compatibility of ISP's

I am working for an electric mobility startup and our aim is to produce electric cars with ADAS/autonomous-driving capabilities. Right now we are in the process of building a prototype. For meeting ...
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1answer
79 views

Detect clusters in an RGB space

With OCR one of the first stages in a processing pipeline is to accurately identify what is print and what is paper, generally achieved by some form of binarization. In the good old days most scans ...