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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Localized Gamma Correction

Question: Is there an algorithm that does (what I would call) "localized" gamma correction? That is, applying different gamma corrections on different parts of an image, using a masking filter or ...
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What is the different of Maximum Aposteriori Probability (MAP) method and image registration with reconstruction in multi image super resolution?

I am working on multi image super resolution (MISR) for thermal imaging. I have read several papers and slide about it but there are some confussions. First, I know that the basic of MISR is combining ...
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Measures of edge image continuity and connectivity

Suppose I have a scalar image $I:\mathbb{Z}_{1,m} \times \mathbb{Z}_{1,n}\rightarrow [0,1]\subset \mathbb{R}$, where $\mathbb{Z}_{1,m} = \{1,\ldots, m\}$. (For instance, computed as the (scaled) ...
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Deriving transformation from input and output images

I will preface this by saying that my undergrad signal processing course is very far back... Context: I am comparing images of global illumination (GI) passes. I want to be able to change the ...
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34 views

Non Circulant Translation Using Fourier Transform

The translation property of Fourier Transform (FT) for a two dimensional image $f$ is as $$ f(x-x_0, y - y_0) = F(u, v)e^{-j2\pi(ux_0/M+vy_0/N)} $$ Using this equation, the following code (in Matlab) ...
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Remove specular highlights from a grayscale image

What methods are there for removing specular highlights from an image without using a threshold? I need to remove highlights from microscope images of droplets in order to recover their approximate ...
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2answers
20 views

Restore RGB Values from Luminance Value?

I am not sure, but can we get RGB (Red-Green-Blue) values from calculated luminance value for each pixel? ...
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3answers
64 views

Can the colors of an image be interpreted as “virtual” Doppler effect?

In astronomy, the Doppler effect is used to estimate approximate distances to stars and other celestial bodies. Using the same principle, lets say we divide an image (photograph) in pixels and that ...
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How would you interpret the pattern in this picture? (generated by re-sorting pixels based on their RGB value)

Was playing with some pictures and ran the ruby code below. The code reads an input image using the ImageMagick library, gets an array of pixels, re-sorts the pixels and then writes out an image with ...
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1answer
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Which Noise Reduction Algorithms Are Used in Commercial RAW Image Processors?

I'm trying to guess what noise reduction algorithms are used in commercial processors for raw images from digital cameras. I find this fairly easy to do for the sharpening algorithms (most use unsharp ...
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1answer
70 views

What Is the Correct Way to Apply Richarson Lucy Deconvolution to Luminance Data?

My question concerns the Richardson–Lucy deconvolution algorithm, which is described in Richardson's original paper. I am interested in applying it in the context of a raw image converter for digital ...
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3answers
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Reduce the number of intensity levels of a grayscale image in Matlab

I have written a Matlab script to reduce the number of intensity levels of each pixel of a grayscale image from 256 to some power of 2. ...
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Implementing rotation in frequency domain and map it back to spatial domain

Please consider the following small example: ...
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Fast and Slow motion video detection using Optical Flow

I'm trying to calculate a "video motion" value in a given video sequence, meaning how fast or slow motion the video is. For instance, if a video is about a car racing, the value is high. Whereas if ...
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What are the Red-Black Wavelets transformation for color (RGB) images?

I am looking for Red-Black Wavelet transform implementation on internet but I am unable to find it. Or How wavelets can be used for Images. Please help if you know how wavelets can be used for images.
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Meaning of “Spotting patterns” in image processing?

I was reading article from engineers garage about image processing When i was stuck/confused at 2nd point of 3 steps of image processing The part of sentence that i am unable to understand is ...
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How to make ground-truth image for document image binarization task?

The two images are from DIBCO (Document Image Binarization Contest). The objective is to find a solution to binarize the top image (original image) to be similar to the bottom one (ground-truth image)....
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Calculating the numerical gradient of a volume in one direction at a time

I want to calculate the gradient of an image volume in one direction at a time. Using the built-in function of Matlab gradient() I can get the ...
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Image processing and object detection in sales force automation

We have a specific requirement in our sales force automation product. Requirement in merchandising module There is one shelf check activity in merchandising where salesman is capturing which ...
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55 views

Digital Image Processing Textbook with Specific Topics

I am looking for a Digital Image Processing and analysis textbook, but there are specific topics that I would like the book to cover. Among other topics, I would like it to include a discussion of: (...
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1answer
63 views

What is meant by product of two images?

I would like to compute the product of two images. I tried with the code below. But the result is not like I expected. Can you tell me where is the problem in my code? https://ibb.co/Njc8w3b ...
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1answer
129 views

How to remove striped noise from this image. Which filter or algorithm use better?

I need to process a gray scale image. The task is to remove the stripes, which constitute some noise. I have next origin image: This image received many channels ADC(Y) in moment of time (Xn) from ...
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Logical Steps to segmenting Lung Fissure Structures

I am given the task to do the Lung Major Fissure Segmentation in a CT image to find it's position in an image. This is what a Major Fissue looks like: https://www.med-ed.virginia.edu/courses/rad/cxr/...
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Difference between low pass/ high pass filter vs Discrete Wavelet Transform

In image processing, DWT is equivalent to apply a series of low pass filters and high pass filters to get the details (such as edges) and approximation (such as overall texture) coefficients . In this ...
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1answer
30 views

2D Multi-scale dot enhancement filter based on Gaussian filter and Hessian matrix

I'm trying to implement an algorithm that enhance dot and line like structures based on Hessian matrix, the algorithm uses Gaussian filter with different scales before calculating the hessian matrix ...
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Would an object detector or image classifier better identify pages with tables?

I want to use some kind of CNN to detect whether or not scanned PDF images contain tables. Should I use some well-known image classifier, trained on a dataset I label, to identify pages that have ...
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1answer
23 views

morphological processing : Hit or Miss shape detection

I am currently looking at shape detection for Hit or Miss. I am having a bit of trouble with the concept of the window that they have you to detect the shape. Up till now reading about hit or miss ...
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need tool to identify most focussed image in a series

I have a situation where I am sent a series of photographs of hand-written documents (quite old, from 1850-s). Each photo is done just as you and I would photo a page from a book, so not a ...
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2answers
35 views

Transforming RGB images including NIR to LAB

I'm relatively new to image processing, so I hope I don't ask trivial questions. I have some images that I want to use in a machine learning context. The images have four color channels: RGB and NIR (...
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39 views

What is the point spread function and optical transfer function and what uses are they in image processing

So I seem to really be struggling with the concepts of the point spread function (PSF) and optical transfer function (OTF) and what they are used for in image processing. Everything I seem to google ...
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1answer
25 views

Develop a simple image classification system by using Laplacian of Gaussian (LoG)

I am tring to write a simple CAD system to classify some images within two groups by using Laplacian of Gaussian (LoG). I am using scikit-image for this tasks and I want to use DNN in keras to train a ...
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Thermal image based segmentation [duplicate]

I'm working on a project to do segmentation of thermal images. So far, the methods have produced limited segmentation performance (k-means, Otsu's Method, Sobel, Canny, LoG). I am trying to achieve ...
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BRIEF feature vector random point sampling 3rd method

When using the BRIEF algorithm to generate a feature vector, 5 methods are provided for selecting 2 random points inside a feature point patch. The 3rd method is described as follows: Let consider ...
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1answer
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How to partition collagen into separate fibers?

I have a picture representing collagen fibers of a tissue: Image is binary consisting of a background (pixels with value 0) and white collagen (pixels with value 1). A zoomed in section of an image ...
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Removing striped noise from an image

I was just wondering if anyone could explain to me the approach one would take to removing striped noise from the fourier domain of an image. I was reading an article about MRI image from 1 just ...
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1answer
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Gender classification using Periocular Region [closed]

I have a dataset of the periocular region, I have images of the male and female periocular region but they are only labeled as left and right periocular region, Folder is a mixture of male and female ...
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Size filtering on binary images

I have noisy images from which I extract the contours using OpencCV's findCountours, which performs binarization internally. This results in innumerable small ...
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1answer
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What is the difference between positive matrix coefficients and negative matrix coefficients of an audio?

I have turned an audio file into an one dimensional array by using audioread function in matlab and found several positive and negative fractional coefficient values.What is the basic difference of ...
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1answer
46 views

How can I detect the tree rings?

I'm looking for the way to detect the tree rings automatically in the wood dist image. Using the matlab, I have removed the background, and binarized the image. How can I detect the white and black ...
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Questions about Optical Flow implementations

I have some doubts related to some of the optical flow implementations. How to compute angular error for optical flow algorithms? I know the formula for computing, $\theta=\arccos(\vec{v}_c\cdot\vec{...
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What is the name and theory behind a basic motion filter with background update?

I am working on machine vision task. I am using openCV in Python. I need to detect motion. Best would be if I can calculate the difference between the new image and background. However, the ...
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can I combine 2 raster with wavelet transform in R? [closed]

I Have same problem, i will combine 2 raster data with wavelet fusion r1<-brick("mask data/r1_mask_black.tif") r2<-brick("mask data/r2_mask_black.tif")
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Detect Colors in an image using opencv python

How to find different colors present in an image? Is K means clustering enough or any other simple way of doing it using opencv exist?
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Understanding Upsampling Filter in Laplacian Pyramid

For the construction of a laplacian pyramid, images are downscaled and then upscaled again. My question is what is a wise decision of the kernel mask for the upscaling task ? In more detail, lets say ...
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Kalman Filter in Vision - Constant Velocity Model - Units

Let's assume we have series of frames with a known object. I want to track the object using Kalman filter using constant velocity / acceleration models. My questions are: (i) Which model to use? CV ...
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Weight update in particle filters

For particle filtering weight update, often the transitional prior is used for the proposal density, in which case the weight update simplifies to just the likelyhood function. However, in one ...
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2answers
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Camera image pixel structure origin

I am using machine vision for industry task with opencv. I have images from a camera monitoring the process. The detailed look at the small part of the image follows: Enlarged: In the detail, it ...
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drawing a line from where the tires meet the ground

I followed these steps to write a program in Matlab to detect the edge of the wheels where they meet the ground. Step 1. read the image Step 2. k-means segmentation Step 3. Dynamic binarization ...
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Making sense of indices in 2D convolution operations

Referring to the answer here: https://www.quora.com/Why-are-convolutional-nets-called-so-when-they-are-actually-doing-correlations, the equation for a discrete 2D convolution is specified as: $$C(x,y)...
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How do I detect the sharp edges in the following image?

I am looking to count the sharp pointy triangular things in the image. However I was unable to do so. One approach I did try was take a convex hull of the contour and then find convex defects but it ...