# 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.

2,455 questions
Filter by
Sorted by
Tagged with
11 views

### Infrared image dataset for enhancement?

I'm working on near infrared image enhancement. I'm searching for low-contrast images. Example image is below.
711 views

### Calculating the SNR of a blurred image

I have a blurred and noisy image $X$, I want to apply the Wiener filter on it and get a deblurred and denoised image $Y$ (i.e apply inverse of blurring filter while at the same time reducing some ...
1k views

### Finding circle in binary image (R, not matlab)

How would I go about extracting the circular area of a binary image which looks like: The two rods emerging from the side of the circle are noise. I know of the hough transform in Matlab. However, I ...
191 views

### 2D DWT computation order

In 2D the discrete wavelet transform (DWT) of an image using lifting based 5/3 filter, if I perform a row-wise operation first then perform column-wise operation then I will get 4 sub-band LL, LH and ...
32 views

### Designing a 2d low pas filter in fourier domain for an image

Firstly this is not a homework question. I am working on a project and my professor gave me this task so I can also learn about filters and fourier domain. I have a picture that is 2800 x 4500 pixels....
13 views

### 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: ...
102 views

### How to Describe the Color of an Image Patch?

I want to describe the color of an image patch (say, of size 5x5) centered around a pixel of an RGB image. The most straightforward way to do that is to calculate the average color over that patch and ...
64 views

### Are all images 2d or also we have 3d images?

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?
231 views

### How can I properly detect a ball moving in a film capture?

I have problem in detecting a ball moving in a flume (image below). since converting the frames into grayscale format didn't work I converted it into rgb and make it more saturated. problems are: 1- ...
112 views

### Image reconstruction using Irradiation

I am a bit confused as to how to go about this. I have a surface [x,y,z] given by: ...
106 views

### How to transform an aerial image

This is the first time I'm diving a little deep into images and computer vision. I have an aerial image taken from a drone (I know the pitch, roll, yaw of the drone and the angle of the camera ...
33 views

### Image processing vs signal processing? [closed]

What are the differences between Digital signal processing and Digital image processing? I already know that image processing is a branch of signal processing and a signal is n-dimensional and image ...
35 views

### 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 ...
35 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 ...
62 views

### 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 ...
93 views

### How to detect the maximum resolvable spatial frequency of camera?

I am trying to calculate the minimum line pixel width that can be distinguished from noise as shown in the camera test chart in Figure 1 where the thinner lines on the left are getting more and more ...
27 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 ...
34 views

### Recommended approach for extracting specific edges from image?

I have several sets of images with a typical image being: and from each image, I would like to extract the top and bottom curves of the object, shown in red here: What are some possible tools I ...
9 views

### Issues to debug source code did in OpenCV through Python

I am trying to debug OpenCV python source codes through MS visual studio code, initially, I put the breakpoint at line 20, but even so, I am facing every time the same error at the command line: <...
36 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)?
2k views

### What Does It Mean by Gradient / Divergence / Curl of a 2D Image $g \left( x, y \right)$?

Suppose, a 2D image is represented by g(x,y). Then, what does it mean by "Gradient of g(x,y)", "Divergence of ...
2k views

### Why is PSNR used for image quality metrics instead of SNR?

I have been trying to determine why is PSNR used instead of SNR for image quality metrics? I have read through several books and most just say that PSNR is used instead of SNR, but don't give a ...
2k views

### How Can Convolution and Deconvolution be Defined for 3D Images?

I am trying to understand how convolution and deconvolution can be represented for 3D images/ stacks of data. I would prefer it, if you built the these concepts from 1D vectors to 3D matrices in terms ...
5k views

### An Intuitive Way to Understand the Sharpen Convolution Filter in Image Processing

Can someone explain sharpen in a non-technical way. So, I don't mean that you need to multiply every pixel with 5 and subtract it with the pixel left, under, above and right.
16k views

### How Does a Convolution Can Be Expressed as a Matrix Multiplication (Matrix Form)?

I know this question may not be very relevant to programming, but if I don't understand the theory behind image processing I'll never be able to implement something in practice. If I got it right ...
74 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 ...
20k views

### Detection of a Circle in Noisy Image Data

I have an image that looks like the one below: I'm trying to find the radius (or diameter) of the circle. I have tried using circular Hough transform (via matlab's ...
151 views

### Multi Scale Shape and Detail Enhancement from Multi Light Image Collections

I have been working on a practical implementation in Matlab of the algorithm Raanan Fattal suggested in the following paper. I couldn't understand the meaning of eq. 11 on page 5: \...
6k views

### Where to get a proper dataset collection for bikes and cars

I am doing a project on image classification and I don't know where to get the data-set collection for cars and bikes.Any suggestions to sites for this purpose is welcome.Also please suggest the ...
847 views

### What Is the Best Color Space to Work with for Hand Detection: RGB, HSV, or YCrCb?

I'm working on hand gesture recognition using C#. I'm using OPENCV for skin detection but its performance is not optimal. So I decided to do some filtering based on color space, but I do not know what ...
21k views

### How do I get the most accurate camera calibration?

First off, I hope this is the correct Stack Exchange board. My apologies if it is not. I am working on something that requires me to calibrate the camera. I have successfully implemented the code to ...
40 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://...
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 ...
22 views

### 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 : ...
3k views

### How to Estimate the Noise of an Image / Estimation of the Noise in an Image?

I want to know how to estimate the noise of an image? Also is this represent the camera's noise? Does anyone know how to estimate the noise of an image or camera? Update: Especially, I want to ...
34 views

### Similarity or Relation between Walsh Hadamard Transform and Slant Transform

Is there any relation between Walsh Hadamard Transform and Slant Transform? Or is there any common property or similarity?
176 views

### Skewed rectified aerial images

I have a series of aerial images from which I would like to get disparity maps for every consequent pair. In order to do that I do a stereo rectification. The problem is that sometimes rectified ...
410 views

### What Are the Differences in Four Different Types of Third Order Image Moments (Skewness)?

I am attempting to analyze images using the third order image moment (aka skewness), but I am having trouble figuring out how to do so. As it turns out, there are four different types of third order ...
455 views

### How to Use Maximum a Posteriori Probability (MAP) in Classification Task

I have a 2D image defined on a region $\Omega$. Let $I: \Omega \to R$ be a gray image. Assume that the region can be separated into $N$ sub-regions $\Omega_i$ such that \forall i,j=1,\ldots ,N:\...
605 views

### Apply Principal Component Analysis for RGB Images

I've implemented a method to compute PCA on grayscale images. I haven't seen PCA on RGB images yet, which left me wondering if it is possible to perform it. With RGB images, is PCA done for each ...
258 views

252 views

### How to Get Rid of Ripples from a Gradient Image of a Smoothed Image?

I have a gray scale UINT8 image. When I smooth it with a Gaussian filter and then compute the gradient image with a Sobel filter in OpenCV, ripples would appear. ...
48 views

### Are there any efficient algorithm to detect circular shape of arbitrary size in an image?

I have images that are 1278 by 1024. They are pictures of a certain product that is rectangular in shape and are about 25mm by 20mm. As a part of a quality inspection process using computer vision, ...
60 views

### 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 ...