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.

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  1. B

    Understanding the Basics of FFT for Image Processing

    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...
  2. A

    Can AI Technologies Interpret and Convert Musical Notes into Audio?

    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...
  3. B

    Image processing with Sobel Edge detection

    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...
  4. A

    Image comparison software (similarity and differences)

    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...
  5. M

    Engineering Image Processing: what is the correct form of the Laplacian Filter

    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...
  6. PainterGuy

    Gaussian kernel in image processing

    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...
  7. M

    Engineering Image Processing: Histograms

    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)...
  8. M

    Engineering Image Processing: Convolution vs Filtering

    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...
  9. Boltzman Oscillation

    MATLAB How can I create an equation in matlab for image processing?

    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...
  10. S

    Find the sampling matrix and sampling structure for R, G and B components

    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...
  11. A

    MATLAB Bilinear spline interpolation MATLAB using MESHGRID and SURF

    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 function...
  12. O

    Java I about how to get a pixel value in Java

    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)...
  13. M

    I How does the inverse square law apply to a focused detector?

    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...
  14. T

    MATLAB High pass filtering FFT2 matlab

    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...
  15. F

    I Maximum Likelihood to find the original data or estimation directly

    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...
  16. T

    I Informational content in 2D discrete Fourier transform

    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...
  17. R

    I 2D Fourier transform orientation angle

    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...
  18. Raazi

    Medical Content based medical image retrieval using barcodes

    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...
  19. Avatrin

    Working with PNG images in Python

    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...
  20. P

    Image Processing -- Haar Transfrom

    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...
  21. J

    MATLAB Highlight an object in an image?

    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...
  22. R

    MATLAB Frequency domain filtering in Matlab

    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...
  23. E

    I How to do the Dark Frame Subtraction? (camera imaging)

    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...
  24. B

    How to convert all pages of a pdf into A5?

    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...
  25. M

    How to interpret a complex Matrix as a Probability Matrix?

    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...
  26. E

    I Horizontal Noise Stripes in an Image

    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...
  27. G

    What is the basis for bessel function as we have for wavelet

    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...
  28. L

    I Why is the Fourier transform of a sinusoid assumed as this?

    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...
  29. stalin

    Why shadows become dark when light intensity increases?

    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...
  30. H

    What I need for image processing programming?

    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...
  31. E

    MATLAB Image Processing and MatLab (Deconvolution Process)

    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 =...
  32. B

    Video Image Processing: Algorithms for Motion Detection

    Is there a computer algorithm that can determine if a person it moving their right arm or there feet, or if they are running or not ?
  33. E

    Shape Detection and Recognition

    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...
  34. B

    MATLAB Want gray scale image of a matrix in matlab

    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...
  35. E

    Fresnel Relations and the Sensitivity of a Camera

    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...
  36. R

    MATLAB Single vehicle tracking using Fourier transform-MATLAB

    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...
  37. R

    Algorithm to compute Basis images of an image

    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...
  38. R

    How to find phase values at neighboring pixel in an image?

    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...
  39. R

    How Can You Extract Specific Signals from a 2D Image Using Fourier Transform?

    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...
  40. R

    What Does the Fourier Decomposition of an Image Represent?

    Hello everyone have a look at this video of Fourier Decomposition of an image.also we know that Fourier series is given in the image as...
  41. R

    Fourier maths behind an image

    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...
  42. J

    Term to express a range of fluctuation

    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...
  43. J

    What is the term for this image processing?

    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...
  44. A

    Programs Image processing skills in biosensors and fiber optics

    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...
  45. J

    Fourier Transform, Discrete Forier Transform image processing

    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...
  46. T

    What kind of image processing techniques are needed?

    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...
  47. J

    Digital Image Processing, Phase offset

    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...
  48. N

    Image processing: effect of illuminant on sRGB image

    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...
  49. S

    Image Processing: Exploring Wavelength, Intensity & HSV/RGB

    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...
  50. C

    MATLAB Java/C++ vs Matlab in Image Processing?

    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...
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