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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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6 views

Measure that Compares an Actual Old Document from a Synthetic Old Document

I have collected dirty background images, below is the sample: I have also a collection of an actual image of a dirty document with text on it, just like below: My problem with my actual image of a ...
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17 views

Find common features across images

Consider multiple images that share a common feature. More specifically, they are the sum of multiple features, and I know that one of those is present in all. What is the best method to extract this ...
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25 views

Salt and Pepper impulse Denoising opencv

I am creating a generic method to work on salt and pepper noise and variants. The example images are as shown below : I tried few methods, such as ...
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14 views

Intelligent lmaging? [closed]

There is a new reasearch field in image processing called as 'intelligent imaging " What is it ? Actually i want to apply for MS in electrical engineering and my target university is offering ...
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Finding defects in wall paint (finding difference in textures)

I have been experimenting with computer vision techniques to find defects in paintings, more specifically defective brush strokes. I have tried a handful of techniques such as different filters, One ...
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Reconstract the image from the modulus of its Fourier transform

In Reference, it is shown than one can recover the image by using only the modulus of its Fourier transform. It provides two iterative algorithm which is really similar to Gerchberg–Saxton method. ...
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Calculate velocity of an object? [closed]

I have a video of a ball travelling through a video and I would like to calculate the velocity of the ball(in mph) at each point in time. I have detected the exact position of the ball in each frame ...
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63 views

confusion sampling vs quantization?

while converting analog signal to digital equivalent,we have a process that is called analog to digital conversion and it has two main steps/stages sampling and quantization? I am confused whether y ...
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video resources for learning image processing?(for EE background)

Please kindly recommend some youtube links for learning image processing. I have EE background and i want to study/learn image processing in this way Also i have confusion that Computer science ...
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30 views

Different representations of frequency space of 2D image FFT

I'm learning images processing using FFT. In my test example provided below the input pixel values are clamped 0-1 (0-255), but I do eventually want to process floating point heightfield pixel values....
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How to create different Time frequency images from a data

I'm new to Python. I have a time series in a CSV file that has about 5000 rows and 3 columns. I have split the data into training and testing in ratio 70:30 respectively. However, I have a problem ...
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How to find position, scale and rotation of a known shape/contour in an image?

I have an image of an object. The image shows a high contrast outline of the object. It is guaranteed that the image shows exactly one object. The shape/contour of that outline is known. It is not ...
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Image extraction post processing to increase similarity

I’m trying to train an OCR model, but I need to get my extracted images to look more like the training images. However I’m not sure of how to go about it and what techniques I can use. For instance ...
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How can I get better results from Phase Correlation

I am using Phase Correlation to register 3D data. There's a clear distinction in the y direction so the resulting shifts seem to be correct. But since there is a lot of similarity in the x direction ...
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3D model from high speed videos?

Is there a way to convert or somewhat replicate RADAR data from a set of given high speed videos taken from multiple angles. The problem is quite ill defined but the task I have in hand is to ...
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23 views

What is the best filter for handwritten signature identification

I'm doing a research about personality identification based on handwritten signature, got a little bit confuse what filter should I use for the identification, any recommendation for it?
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27 views

Smooth factor in matlab

I use smooth function in matlab, in this function there is the smf (smooth factor) parameter that get different values. In different applications, this parameter ...
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2answers
55 views

Nyquist sampling in image acquisition

I know that in the image acquisition stage, after obtaining the analog image from the sensors, it is sampled and quantized. How the Nyquist sampling is achieved? The sampling frequency must be at ...
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44 views

Licence plate enhancement

Is it possible to enhance the image below and make it more readable? I have tried apply binarization but there is some kind of shadow. So I have tried to convert image to gray scale and then ...
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1answer
95 views

displaying an image

The specification of a Sony mobile phone is as follows: Screen: 5.2 inch, 1080 x 1920 pixels Camera: 19 MP, 2160p first, what does the value 2160p represent? Second: multiplying 1080 x 1920 pixels ...
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How to calculate linear index of fuzziness of an image?

i am trying to calculate linear index of fuzziness of an image using this formula: i have to see a positive value according to the paper. But i see a negative value, so i think i am doing something ...
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Could anyone explain the sliding factor and min neighbours aspect of the Viola-Jones detection?

I'm looking at code that has a scale factor of 1.1, presumably meaning it's being increased by 10%, what are the advantages of this? Secondly, I don't understand what minNeighbors actually mean and I ...
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1answer
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Fixing edge/pixel defects in image

I have a large number of images that are supposed to look something like the top part of the image: Instead, some have defects in them, as in the bottom part of the image. As you can see, there are 2 ...
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1answer
39 views

Spectrogram of an executable binary [closed]

One of the approaches I have been searching so far is the application of utilizing Neural Network to classify Spectrogram images, which is heavily used in speech recognition. I am conducting an ...
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How to find location of minimum dimension of contour using opencv?

suppose this is our input image and now we have to detect the point of minimum dimension, which I show as the red dot in an output image
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26 views

Measurement of moving objects using computer vision

I am working on a project to measure lengths of the black objects and distance between them using computer vision (Shown below in the fig.). These objects are moving on a conveyor shown in the blue ...
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1answer
29 views

Noise amplification with inverse filtering

I'm trying to gain a better (mathematical) understanding of why inverse filtering is almost never the solution for correcting an image. From what I understand, we start with a discrete signal $s[n]$ ...
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How to improve interpolation for chroma upsampling (4:2:0 to 4:4:4)?

I am trying to perform the best possible interpolation in order to perform proper chroma upsampling from 4:2:0 YCbCr to 4:4:4 YCbCr. I have implemented the improved interpolation proposed at this ...
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How to plot histogram of difference of two images using MATLAB

i would like to calculate difference of two images. Then, histogram of difference of two images. So I can plot a histogram but I am not sure whether it is true or not? Also, I am not sure about what ...
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image resolution in smartphones and laptop [closed]

If I used a smartphone with high pixel per inch (ppi) value for capturing an image with certain dimensions, what happened if this image is displayed on a laptop (larger screen) with: the same ppi ...
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1answer
115 views

Intuition behind image derivative using Fourier Transform for edges detection

This equation can be shown mathematically: $\frac{\partial f}{\partial x}=\frac{2\pi i}{N} \mathcal F^{-1}\left(u\cdot \mathcal F(f(x,y)\right)$ I am struggling to understand the intuition behind it ...
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3answers
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image compression versus image denoising

Wavelet based image denoising may be performed by thresholding (selecting a threshold value, and discarding all values below the threshold. Wavelet-based image compression may also be performed by a ...
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3answers
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Would capturing an image at 640x480 then resizing it to 1280x720 improve the ability to detect/resolve objects in the image?

I work in a research lab and am currently setting up a system to image objects approximately 30 microns in diameter with a 250x USB microscope, then use image subtraction to isolate the objects as ...
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2answers
43 views

Image resizing and interpolation

In digital image processing, I need to understand what does image resizing do? Does it only change the dimensions of the image, for example, from 256×256 to 128×128 with the same pixel spacing (the ...
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Infrared image dataset for enhancement?

I'm working on near infrared image enhancement. I'm searching for low-contrast images. Example image is below.
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I can't implement plateau limit histogram equalization algorithm using MATLAB

i tried to implement this research paper using MATLAB. Unfortunately, my result is not same with the original result. Here is my try step by step: ...
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3answers
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Are all images 2d or also we have 3d images? [closed]

Are all the images that we encounter/use in image processing are 2D or do we also have 3D images? If also 3D, then Video will be treated as a 2D image or 3D image?
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How to Downsample The Chrominance Components

So I am doing an image compression project for college and am trying to create a visual demonstration of how downsampling chrominance components can reduce the amount of digital information while ...
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59 views

Trying to convert Raw image(Bayer format) to jpg/png image in Python

I am using the Sony Low-light image dataset from the paper Learning-to-see-in-the-Dark. I am trying to convert Raw image (bayer pattern in arw format) into a jpg/png. I used an online tool that gives ...
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38 views

Creating a combination of extrusion to a point, and motion blur

I am attempting to generate a effect that allows me to use original color of image, but also mimic a pinched extruded 3d surface from orthographic view. To do this, I used the G'MIC-QT scripting ...
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11 views

Texture Synthesis using Heeger siggraph paper

i am implementing texture synthesis using steerable pyramid using Heeger Siggraph et. Al. paper, link for the paper is here https://www.cns.nyu.edu/heegerlab/content/publications/Heeger-siggraph95.pdf ...
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1answer
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Applying a 2D band pass filter (Butterworth ?) to an array with NaNs

I am trying to filter out the low frequencies of an array looking like this : For now, I am taking transects of this array and applying a 1D - butterworth band pass filter : ...
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1answer
190 views

Running the BM3D Denoising Algorithm in Python

I am looking for a strong baseline in image denoising and therefore wanted to have the BM3D algorithm in my benchmark. These 2 python implementations: https://github.com/ericmjonas/pybm3d https://...
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63 views

Generating Kawase Blur Kernels to Approximate a Gaussian Blur on an Image

Is there an algorithm to generate the Kawase Blur Kernels to approximate the actual Gaussian Blur (of a specific kernel size, and if possible, a sigma)?
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Randomly Generate Synthetic Noise in an Image Text Document

I'm working on denoising dirty image document. I want to create a dataset wherein synthetic noise will be added to simulate real-world, messy artifacts. Simulated dirt may include coffee stains, faded ...
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4answers
78 views

Understanding correlation in image processing using examples

I have been trying to understand the intuition behind the correlation. I understand from this guide that correlation is a way to detect a known waveform in a noisy background. I have seen from this SO ...
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Understanding the Bilateral Filter - Neighbors and Sigma

I have been reading about the Bilateral Filter in - Fast Bilateral Filtering for the Display of High Dynamic- Range Images and have felt crippled and confused while understanding its working and the ...
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What does dynamic range values in SSIM image quality technique refers and how to calculate?

http://en.wikipedia.org/wiki/Structural_similarity Below is java implementation of SSIM. ...
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2answers
82 views

why do directional derivatives work better with a gaussian filter?

I've been working on image segmentation and computing the directional derivatives of a grey-scaled image, with the objective of detecting contours and edges. I have realised that if I apply a gaussian ...
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What are the measurable factors of image sharpness?

I need a way to present data on an essay written about image sharpening algorithm. So I've thought that if I measure a factor of sharpness from image or relative sharpness (between test img and ...