What is Image processing: Definition and 79 Discussions
Digital image processing is the use of a digital computer to process digital images through an algorithm. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing. It allows a much wider range of algorithms to be applied to the input data and can avoid problems such as the build-up of noise and distortion during processing. Since images are defined over two dimensions (perhaps more) digital image processing may be modeled in the form of multidimensional systems. The generation and development of digital image processing are mainly affected by three factors: first, the development of computers; second, the development of mathematics (especially the creation and improvement of discrete mathematics theory); third, the demand for a wide range of applications in environment, agriculture, military, industry and medical science has increased.
if you watch this Video :
The Julia Programming Language
at time marker 28:00, You will see that Grant takes an FFT of an Image.
In order to do a FFT, you need to know the sampling rate, but what is the sampling rate of one image?
And what if your image is not size 2^N ? Does the program just...
Musical notes
Can AI, Machine learning, Data science, Computer vision, image processing technologies assist in interpreting musical notes ?
Input dataset : Musical notes
Output : Sound (Audio file) played.
A python program which can assist in interpreting or converting text to speech ?.
The...
I am coding Sobel Edges detection in C#.
I have a method that converts my image to grayscale.
it adds the R G and B values and divides by 3. and replaces the R G and B value out with that same number. That seems to be working fine.
Then I added a gaussian blur to it by using this...
Images comparison
What are the best softwares available for comparing two images having similarity and differences?
Two photos each of Margaret and Enid.
1 Margaret's first photo with her second photo comparison.
2 Enid's first photo with her second photo comparision.
3 Margaret's first...
Hi,
I just have a quick question regarding image processing. What is the correct form of the Laplacian for image processing?
I have seen different versions online and don't understand which one is meant to be the conventional one. I know that:
\nabla^2 f(x, y) = \frac{\partial^2 f}{\partial...
I was reading the following webpage on Gaussian kernel but couldn't understand few details: https://www.imageeprocessing.com/2014/04/gaussian-filter-without-using-matlab.html . Would really appreciate it if you could guide me. Thanks in advance!
Here you can find the high-res screenshot of the...
Hi,
I was just looking at some conceptual problems on the internet and wanted to check whether my thought process on this question was correct.
Question: The two texture images shown below are quite different, but their histograms are identical. Both images have size 80 × 80, with black (0)...
Hi,
So my question is perhaps better asked as:
- What is the point of convolution (in 2D image processing)?
- Why would we use that operation in image processing?
- What is so special about that flipped version of the kernel?
Context:
In an image processing class, I was learning about the...
Here is the documentation for the 2DFFT:
https://www.mathworks.com/help/matlab/ref/fft2.html
how would I go about creating this formula on MATLAB to apply it on an image? My guess is that I need to create the equation and then multiply it to the image I need such as:
$$U = VI$$
where V is my...
Hello, everyone. :)
All I could gather is that, if I'm correct, lattices are spans of the column vectors of the matrix within the "LAT()" notation and the X and Y occurrences are unit placeholders (such as the pixel unit (since this is in the context of image processing)).
And, as an attempt...
Hello.
So, I must provide a solution for an image processing course I am taking (implemented in MATLAB).
The task is as follows:
1. I must provide a MATLAB script that takes in a DISCRETE N x N matrix (Greyscale picture) and does Bilinear spline interpolation on it.
This is the spline...
Greetings!
Hey guys, I need help on how can I get pixel value of an image with pixels more than 100px (10x10).
Here the code that I execute in order to get the pixel value
try{
File f = new File ("input image location");
BufferedImage img = ImageIO.read(f)...
I am interested in evaluating light intensity variation in a digital image. A colleague wants to apply an inverse square law correction to account for distance variation. I am trying to justify that in this case, the inverse square law does not apply.
Treating each pixel as a detector, it has...
I am having a slight issue with my code and honestly cannot understand what I am doing wrong. I am currently trying to using a high pass filter in the frequency domain to form the following image.
So my approach so far after numerous of attempts which I won't list as I believe I am on the...
I make confusions in the using of Maximum Likelihood to find (approximately) the original signal knowing the data observed and the using of Maximum Likelihood to find estimations of parameters of the PSF
1) Find (up to some point) the original signal :
I start from this general definition (in...
When you do a discrete Fourier transform (DFT) of a one-dimensional signal, I understand that the second half of the result is the complex conjugate of the first half. If you threw out the second half of the result, you're not actually losing any data and you would be able to recreate the entire...
The orientation of frequency components in the 2-D Fourier spectrum of an image reflect the orientation of the features they represent in the original image.
In techniques such as nonlinear microscopy, they use this idea to determine the preferred (i.e. average) orientation of certain features...
Hi,
I am doing research in content based image medical image retrieval using radon barcodes. I have replicated an approach found in this paper 277011226_Barcode_Annotations_for_Medical_Image_Retrieval_A_Preliminary_Investigation. I have tried to make some improvements to this process regarding...
Hi
I have to run a few algorithms using Python on PNG-images. However, I also know that PNG is compressed... How do I do this? I need to learn the following:
1: Extracting the RGB information about the pixels.
2: Isolating parts of the image (for example, importing an image and only working on...
I'm looking at this link: HaarWaveletTransform. Given an array of N sample points, it subdivides the array into two arrays of size N/2:
Array1: Averages adjacent sample points. Array2: Computes a finite difference between sample points.
You can then apply recursively k many times. In the end...
Hi Everybody
I'm a new user and hope I have posted in the correct section.
I'm a beginner in MATLAB and image processing.
Using matlab, I have to highlight in an object in an image.
I have an input image where there is a plate with a food. I need to produce an output image where only food is...
I am trying to implement several filters in Matlab for Fourier domain filtering. They are the cosine, Shepp-Logan, and Hann/Hamming window filters. These filters are defined as multiplying the ramp filter by the cosine function, sinc function, and Hann/Hamming windows respectively.
This is how...
I have an image with uneven contrast. Now to correct the image, I need a dark frame to remove the noise inherent to the sensor or to the camera itself. How can use the dark frame into the image? I have been searching the net but most of them use photoshop or similar softwares. How can I apply it...
I have a PDF file in which different pages are of different size because I made it up from images of different sizes. For printing purpose I want all the pages to be of A5 size, How can I do that ?
Sorry if this is silly but I have no experience in working with PDF, this is the first time I...
Hello everyone,
I'have implemented a Maximum-Likelihood-Expectation-Maximization Algorithm in order to reconstruct a bild.
let say, we have such a system Ax=b, where A is a complex matrix, b is a complex vector.
A and b are known and we will iterately try to find the best x (which should be...
What are the possible causes of the horizontal noise stripes in this image:
http://dsp.stackexchange.com/questions/20061/removing-periodic-noise-from-image-using-fourier-transform
I'm currently studying on these kinds of noise, and how to eliminate them. Can these be caused by diffraction...
Hi,
I have recently studied about basis for wavelet function which is helpful to design any function. Likewise, what is the basis for bessel function and how can it be implemented for an image ( because image is also a function). Specifically, I am interested to know how bessel function can be...
Hello everyone.
I'm trying to better understand structured illumination microscopy and in the literature, I keep coming across bits of text like this.
Source: http://www.optics.rochester.edu/workgroups/fienup/PUBLICATIONS/SAS_JOSAA09_PhShiftEstSupRes.pdf
From Fourier analysis, if I take the...
I observed following phenomena today: in my room with some lightings, there is a stuff toy placed in front of a wall. The ambient lighting doesn't cause any shadow on the wall currently. Now, I switched ON a torch and pointed it to a stuff toy which was kept in front of a wall and a shadow...
I am new to image processing and going serious from now on (as part of my research). I am a Mac user. What program is the best for image processing?
What the difference between Xcode and Microsoft Window Visual, which one is better and does OpenCV can works with both of them?
What kind of...
I have these two images:
And I have this impulse response function, or the point-spread function (PSF):
The first image is the actual size of the PSF, and the second image has zero pads included.
I tried deconvolving the images this way (with MatLab):
deconvolved_image =...
How can I detect shapes in an image using an algorithm? I have heard of using edge detection and from there the shapes can be identified, but how? Also, edge detection only is effective if the shape has a high difference of contrast from its surrounding area, what would be an effective technique...
I am creating a gray-scale image of a 2000*2000 matrix using mat2gray and imshow command.But highest number of matrix entries that imshow can implement is 500*500 approximately.After that it shows------
"Warning: Image is too big to fit on screen; displaying at 8%
> In...
Reflectance, according to the Fresnel Relations, is given by
##R \equiv \frac{I_r}{I_i}##,
and Transmittance is
##T = \frac{I_t \cos \theta_t}{I_i \cos \theta_i}##.
Do these values depend on the wavelength of light? For example, if I have a beam of white light rather than a monochromatic...
I am working on a project which is based on importance of phase only reconstruction of a signal obtained from fft.
Now ,I have detected vehicles from the Video of Traffic on road taken using stationary camera ( Please download the 1.47 MB video for testing MATLAB Code by ( step1) click on the...
I know from the Fourier Analysis
that any signal can be represented
as summation of elementary
signals i.e. basis functions
.Likewise,any image can be
represented as summation of Basis images.
Is there any available code, or
even an algorithm, that would
allow me to compute Basis images
of an...
I have computed magnitude and phase spectrum of very famous image of cameraman using fft function in MATLAB.Here,we get magnitude and phase spectrum of the whole image. But I want to find phase values of the neighboring pixels .
So if given gray scale image is of dimensions 256*256 and if I...
Suppose 3 1D Signals x(t), y1(t) and y2(t) are given as
x(t)=sin(40*pi*t);
y1(t)=.5*sin(40*pi*t) and
y2(t)=x(t)+y1(t).
Left side =Right side
Here,values of x(t)and y1(t)i.e.(Right side) are given and we get y2(t)(Left side).The plots of x(t),y1(t) and y2(t)
are plotted below...
I am beginer in image processing.
Any signal whether it is 1D,2D or
any multidimensional signal can be represented using combination of number of sine and cosine
waves.Similerly any image can be
termed as a sinusoidal function.
Fourier series and transform plays
vital role in image processing...
I am trying to make a term for a function equipped on an image sensor.
The term is to express "the upper limit of fluctuation allowance in image size which is specified in %"
The value of percentage does not express the ratio of the enlarged image size compared to the original image size, so...
How do you call of the digital image processing that simplifies an image by reducing the amount of pixels?
I thought of the word “thinning”. But according to ”Fundamentals of Digital Image Processing” by Anil K. Jain, “Thinning algorithm transforms an object to a set of simple digital arcs...
I am currently pursuing a Master's degree in physics with optics as my major and my interests are fiber optics and biosensors. I have also worked on a couple of projects in the past that dealt with a lot of image processing.
I will soon begin working on my Master's thesis and want to decide a...
Hi all,
Now naturally after completing a physics degree I am very familiar with the form and function of the Fourier Transform (FT) but never have grasped it quite conceptually. I understand that given a function f(x) I can express every functional value as a linear combination of complex...
Mod note: Fixed the links to the two images
Second mod note: the links are broken again
Hi, all
I have recently faced with an abstruse problem in image processing.
So, I would like to ask somebody's advice.
There are two images below; one is original and the other is an impaired...
Homework Statement
I'm working on a Matlab problem for a digital image processing class. The problem is to take an image, then take its 2D-FFT and offset the phase component by pi. Then to take the IFFT of the new DFT using the unmodified magnitude and modified phase.
What I got was a...
Homework Statement
Assume an image file is sRGB under D65. Generate the image as it would appear under illuminant A ( a 171x1 matrix).
Homework Equations
effect of illuminant:
B = LA
where A is the a color matching function, L is a diagonalized version of illuminant A, and B is...
I was working on an image processing project a while ago and was specifically working with raster images in the Hue-Saturation-Value(HSV) image format. Each is determined by mathematical values of these (HSV) parameters. I also worked with other bases such as the Red Blue Green (RGB) format. Now...
I just recently picked up MATLAB and still learning its syntax and built-in functions. I am working on a project that deals with image analysis, such as extract every pixels from an image and analyze them in forms of matrices.
I am more experienced in Java than C++ or Matlab. I also feel...