Questions tagged [image]
This tag covers signal processing where input is an image, such as a photograph or video frame and the output could be an improved or altered image, parameters related to the image or information about features within the image.
508
questions
0
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0answers
96 views
How can I turn an image into a scatterplot?
I'm doing a research on how to do image classification for embedded systems with 64kB flash and 16 kB RAM and Deep Learning won't work here Therefore, I need to use simplier tools that still have a ...
2
votes
1answer
39 views
Ideas on detecting holofoil trading cards?
I'm relatively new to image processing but am working on a trading card sorting machine, and would like to detect holographic cards. I'm currently identifying cards using ORB matching (moved from p-...
2
votes
3answers
151 views
Understanding FFT output in Matlab
I'm very new to Fourier transform and I want to plot the Fourier transform of an image in Matlab. I've seen many examples and in all of them, the fft() of the image is a black picture with some white ...
0
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0answers
6 views
Eliminating shadow-like noise from wafer map images
I'm trying to eliminate a shadow-like noise from the wafer images and only leave the most prominent defects as shown in Image1 below.
I thought I could treat it like salt-and-pepper noise. Hence, I ...
3
votes
0answers
49 views
Overall approach for building a footfall/age/gender counter using CCTV footage
I would like some advice to validate my approach for building a computer vision system.
Design brief:
Using existing CCTV cameras in a retail store, detect the footfall in the shop (count individual ...
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0answers
13 views
Are the sparsity of transform coefficients comparable when their frequency ranges are different?
I have obtained a graph-based Fourier transform from an optimization problem, and for evaluating the sparsity of transform coefficients, I was going to compare it with other transform coefficients ...
0
votes
1answer
20 views
Synthetic channel creation using linux software
I have a RGB image in FITS format (though I can easily convert it to another format if that makes things easier). I wish to use the R, G, B channel data from each pixel in the original image, weighted ...
0
votes
0answers
37 views
Removing the Dot-Patterns Like Noise
I am dealing with an image restoration problem with noisy measurement. I use the classical total variation norm to remove the noise, specifically, the TV-$L_2$ problem. I used the famous Lena image ...
2
votes
1answer
26 views
Generate a PSF based on MTF Mapper's SFR measurement
Not sure if I should post this here or on Stack Overflow
I have a .csv file from MTF Mapper with 2 columns from SFR measurement - frequency and contrast:
...
1
vote
2answers
41 views
How to quantify the asymmetry of an image?
Now I have two images:
We can see that Figure 1 shows obviously asymmetry while Figure 2 is totally symmetric. Now I would like to quantify the asymmetry of Figure 1. Is there any reliable and ...
0
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0answers
8 views
How to convert images in a testing folder into a one dimension vector?
I have a sample of 200 images in a folder called training, The dimensions of each is 112*92. I have a problem reading the ...
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0answers
35 views
Why is this minimum cost function returning an insane cost of registration value?
I have a sample program that uses the minimum cost function to align image B to image A.
The method takes two arrays of points and does the summation of all the points in the images for both Matrix A ...
1
vote
1answer
38 views
IP Block and Integrated Circuit using Image Compression and Parameters
I have to research and compare IP cores for FPGA and ICs that use image compression algorithms.
1.) I couldn't find any IP Cores apart from a few IP Cores(JPEG IP Core KJN Series). At the same time, I ...
1
vote
2answers
48 views
Trouble understanding how image digitization works
Quoting Image Processing, Analysis, and Machine Vision, 4th ed.
An image to be processed by computer must be represented using an
appropriate discrete data structure, for example, a matrix. An image
...
2
votes
1answer
52 views
Expression of the convolved image
I have an image of a 2D-sinusoidal pattern $f(x, y)$ with wavelength $\lambda$ which I would like to convolve with a 2D circular pill-box function $h(x,y)$ of radius $r$.
The image is given by
$$
f(x,...
0
votes
0answers
35 views
Image Z Coordinate Clarification
I'm trying to understand 3D image reconstruction, and want to clarify how we can find a z image coordinate.
Is the z coordinate for image coordinates (x,y,z) the focal length since that's the distance ...
2
votes
1answer
28 views
What exactly is "connectivity" between pixels in an image?
So, my professor says that two pixels are connected if:
they are neighbours; and
their intensities satisfy a specified criterion of similarity.
And depending on the type of neighbours they are, they ...
1
vote
0answers
36 views
Convert pictures from the same camera with different FOV to pictures with same FOV
I have a camera device that produce two pictures at the time:
depth picture with FOV: 87° × 58°
RGB picture with FOV: 90 × 65°
I expect that they "share" the same objective so their origin ...
0
votes
1answer
43 views
Image conversion - raw ultrasound data to convex image
As a project, I'm trying to decipher raw data coming from a medical ultrasound device.
The data contains a 128x1008 matrix. Each one of the 128 columns represents a sensor element. Each row in each ...
0
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0answers
15 views
how to identify the main segmentation step in a paper?
I am trying to summarize the segmentation methods submitted in the Cell Tracking Challenge. Currently, I'm having a problem in identifying the main segmentation step used in each paper. How to ...
4
votes
1answer
48 views
How to Remove Temporal and Fixed Pattern Noise and Apply Tone Mapping?
I have a video, whose frames I have extracted and require to work with. 16 bits and grayscale images.
My task is to improve the quality of the images, by removing the noise + adding tone mapping and ...
0
votes
0answers
15 views
What are some good references that define images from a statistical point of view?
I know that images can be studied and understood as 2 dimensional signals. However, I hope you can point me towards references that define and present images rigorously in terms of realisations of a ...
0
votes
2answers
345 views
Is there a way to find the contours of instances in a binary mask image by color?
I need to find the contours for each of the instances of microscopic cells in a binary image mask of dimensions 256 x 256 shown below.
My approach involves thresholding the image to get a binary mask ...
7
votes
2answers
168 views
Locate Non Homogenous Areas in an Image
I need to choose some points on an image. These points should be chosen more where there is lots of color changes, transitions and variations. Which techniques can I use for determining where most ...
2
votes
1answer
72 views
Basic Wiener application
I'm trying to filter this $g(x,y)$ WGN added
image
My Wiener filter is:
$$H(u,v) = \frac{P_{f}}{P_{f}+P_{n}}$$
Where the image power spectral density $P_{x}$ is estimated as $\frac{|X(u,v|^{2}}{N^{2}}$...
0
votes
0answers
81 views
How to enhance thermogram image in grayscale?
I'm trying to do some image processing to improve the image below but I'm having some trouble. I already tried to do histogram equalization followed by laplace sharpening, I tried to implement a ...
0
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0answers
31 views
How would you process this image?
I got this image:
I need to keep only the part in the center (I mean, the circle with texture inside). How would you do it in Python? I'm trying to use Hough Transform, but some times it detect wrong ...
4
votes
1answer
48 views
What is Label Refinement in the Context of Image Segmentation
I have been reading the paper entitled Measures of Similarity by Unnikrishnan and Herbet, in which they discuss some metrics to evaluate image segmentation. They use the word refinement of labels/...
0
votes
0answers
81 views
Removing feature matched outliers within same image using RANSAC
I'm a student working on a copy move forgery detection algorithm.
I have a forged image. By far I have,
Found keypoints and descriptors from the image
Matched the descriptors using 3 Nearest ...
0
votes
0answers
17 views
How can i center the optical mark image?
I want to recognize optical mark using image processing algorithms. There is a wide variety of optical paper and i want to recognize all off them. For example; If i create a template I can superimpose ...
1
vote
0answers
44 views
Image downscaling methods
I am researching downscaling methods for image downscaling. I've both read and found area-averaging to work well in Python using CV2, but the settings in MATLAB allow for it's bicubic interpolation ...
0
votes
1answer
88 views
What exactly is a connected componnent in an image?
The following is a paragraph from "Digital image processing, 4th edition, Gonzalez and Woods".
Let S represent a subset of pixels in an image. Two pixels p and q are said to be
connected in ...
0
votes
0answers
219 views
Image convolution using FFT
I just can't get my head around Fourier transform and convolution in 2D. I am trying to implement image convolution using fast Fourier transform (in julia). So the first thing I need to do is to pad ...
1
vote
1answer
64 views
T1 Mapping in Python?
I'm trying to write a simple program to perform T1 mapping of a few MRI Images.
My understanding is that all I need is to plot the pixel intensity values by inversion time then fit a curve. The output ...
0
votes
3answers
87 views
Beginner Educational Resources
New member here. Recently got hired into a mid level EE position. Have a BSEE but performed more radar performance analysis at a higher system level previously. In my new group we're doing a lot of ...
0
votes
0answers
93 views
How to calculate the magnitude while calculating Blur in an image using using OpenCv based on Fast Fourier Transformation
I am working on image blur detection and found 3 methods for it. One is Laplacian Method but it works good with Gaussian, average, median and other distribution ...
0
votes
1answer
56 views
How is non-integer upres downres (1080p game on a 1440p screen etc) calculated
Please redirect me if this is not the right place to ask.
I was unable to find a straightforward answer to this question. What I am wondering is, if I am playing a 1080p game on a 1440p display, what ...
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0answers
12 views
Correlated signal components from uncorrelated and incoherent source after reflection
To this point, it has been assumed that the point sources
composing the source are uncorrelated, generating fully
incoherent signals. Thus, capturing the reflected signals and after sufficient time ...
0
votes
1answer
183 views
How to come true the convolution with a 2-D array in frequency domain with python
I use the pretty simple example used in many books to understand the convolution in the frequency domain. But I cannot find the real results.
...
0
votes
0answers
18 views
How to obtain height above ground, angle the pixel’s local surface normal makes with the inferred gravity direction from depth map of image?
For extraction of the HHA features from the image depth map we need to calculate the height above ground, angle the pixel’s local surface normal makes with the inferred gravity direction. How to ...
0
votes
1answer
49 views
SAR spotlight raw signal database
For practicing spotlight processing, i am looking for I/Q baseband signal from a SAR airborne or spaceborne system. In my research I have only found processed image from :
eoweb geoportal https://...
1
vote
0answers
1k views
How to make a contour smooth in OpenCV
I am using OpenCV(4.5.1) and trying to extract a smooth contour of an object on my image.
Firstly I got the contour by:
...
-1
votes
1answer
92 views
How to find a pixel's image coordinates by its rgb value in MATLAB? [closed]
How would one find the pixels that match an RGB value in a matrix in MATLAB?
Let's suppose that I want to find the image coordinates of pixels whose value is $RGB=(144,127,11)$ for a given image in a ...
1
vote
1answer
254 views
kernel to calculate second order partial derivative of digital image
I'm working on image stacks, and I need to calculate second order partial derivatives of it.
I already know how to calculate derivative on x and y axis, using Finite Cameron Taylor - Difference ...
0
votes
0answers
35 views
What is the between spatial frequency of an image and pixel size of the sensor?
In my lecture notes about the sampling of an image I've written that:
Since pixels have a finite dimension the spatial frequency response is attenuated before the "ideal" Nyquist frequency
...
1
vote
0answers
49 views
Multivariate Histogram Matching for Image Color Matching
Suppose X is random variable that is spatial position in finite range, which its Cumulative Distribution Function (CDF) could be calculated easily, then if I have two random variable X and Y spatial ...
3
votes
1answer
44 views
Where 2-D DFT is necessary in image processing applications instead of 2-D DCT?
As we know the 2-D DCT is a real-valued kernel and less computational complexity and it used in several image processing applications like image compression etc. 2-D DFT is a complex kernel and high ...
4
votes
1answer
816 views
Is the Laplacian Filter an High Pass Filter (HPF)?
Is this kernel name as mean difference kernel or Laplacian filter?
Is mean difference just a method?
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0answers
23 views
Feature extraction for IRIS recognition
What are types for feature extraction in iris recognition? How can I divide it on types which detect phase, edge, etc.?
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0answers
24 views
feature extraction techniques for iris recognition
I want to ask how I can divide feature extraction techniques to feature detectors and feature descriptors. I have big problem how to understand it. For example I can use Gabor filters (feature ...