# 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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### What is the Center Frequency of Gabor Filter?

If the standard form of a Gabor function is as follows,  g_{\lambda, \theta,\varphi, \sigma,\gamma}(x, y)=\exp\left(-\frac{x'^2+\gamma^2y'^2}{2\sigma^2}\right)\cos\left(2\pi\frac{x'}{\lambda}+\...
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### What is the difference between “tree-based clustering” and “tree-based classification”?

Clustering is an unsupervised learning method and classification is a supervised one. I understand that a tree can be used for image classification since it is based on decision tree in which we have ...
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### How to match a thumbnail to an area in the original image?

Suppose that you have a thumbnail and the original image from which it was generated. You need to match the thumbnail to an area in the original image that represents the original selection from which ...
40 views

### Counting percentage of fouling on a surface

I am completely new to image processing and python. I hope I can find some help here. I am trying out a project on detecting fouling% on a ship hull using raspberry pi. I am trying to learn how this ...
352 views

### How is the luminance vector calculated for these linear matrix transforms

In the article "Matrix Operations for Image Processing" by Paul Haeberli there is an example described using a matrix to alter the saturation of an image. In the example given the author first ...
512 views

### Segment highly packed nuclei with dotted high intensity signal inside each object

I collected high magnification images on cell nuclei and I need to segment them (red circle in the image). The edges of the nuclei are visible but inside each nuclear object there are bright spots of ...
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### DICOM Processing

I am trying to perform analysis of DICOM ultrasound images that have vascular flow rates. I am a new user to MATLAB, and I am trying to generate a line to fit the flow curve and calculate an area ...
60 views

### How to detect malformed-ellipse-alike objects?

I need to process a stack of ultrasonic images, where there is mostly a lot of noise to see, but I need to extract specific objects that look for example like this: Here is an example from Wikipedia ...
39 views

### Evaluation of circle detectors

I have several circle detectors. I want to evaluate their performance in finding the spherical steel markers in X-ray images. The radii of the circles are distributed in a narrow range around 8 px. ...
308 views

I am looking for an efficient head pose estimation algorithm from facial features. What I already have: I already have implemented the code for stable facial landmarks(68 landmarks on the face). I ...
231 views

### Image processing: High pass filter to remove lowest 16 frequencies

How can I remove the lowest n frequencies of an image? Are the lower frequencies around the centre of the FFT result?
552 views

### how to compute horizontal angle of a pixel from a computer vision camera

My program needs to compute the angle of a pixel from a computer vision camera that has 120 degrees field of view, and resolution of 640 pixels wide and 480 pixels high. Program receives an X,Y array ...
343 views

### ImageJ Object Detection within AVI Stack

I am working on a project in which I am attempting to analyze a fish within a petri dish using ImageJ and an AVI clip of the fish under a microscope. My first hurdle is to locate the fish within the ...
32 views

### To estimate the uncertainty of Slicing holes from an image?

I am thinking to estimate the uncertainty of holes photographed from the bottom and top side. The difference of the same hole photographed from two sides is distributed as Gaussian. The length of ...
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### Object detection algorithm

I need detect object in series of pictures. This object has something like nonsymetric relief structure with some irregularities. In this conditions. Light conditions can change from almost dark to ...
2k views

### How to use wavelet decomposition for feature extraction (of fMRI images)?

I have a dataset consisting of fMRI images (from mice) which are divided into 4 groups (different drug dose levels applied). Each fMRI image is 4D, that means each voxel is a time series. For each ...
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### Can Log Gabor Filters be used on an edge detected image

i'm doing a project on log gabor filters, can i use log gabor filter on an edge detected image for feature extraction,and use these features for classification by ANN
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### Isolating overlapping image

Using a diffraction grating in front of my smartphone's camera, I can decompose light sources into their spectral components. The problem is that the background is not always dark and there might be ...
133 views

### Fill incomplete holes in 3d image

I'm trying to analyse a series of CT scans of coral samples, but am fairly new to this sort of image processing. The problem I've hit is that a lot of the coral is hollow (in the images), and even ...
192 views

### Optical Flow Problems

I was wondering if any of you guys could help me with the next 3 problems. They're about estimating the lamda on the Optical Flow equation $E = E_s + Ī»E_c$, for different situations that try to ...
116 views

### Filtering an image with a helmholtz-type equation

I'm attempting to apply the following PDE as an image filter to smooth a discrete heightmap with a helmholtz-type equation as described in this paper. It seemed like an interesting alternative to a ...
477 views

### Initialization of population for genetic algorithm in matlab

I randomly generated initial 10 population(let each of size n) of genetic algorithm as follows ...
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### 3D point cloud to 2.5D graycale image (metric) [Halcon?]

I have a problem ragarding transferring a point cloud to a 2.5D metric grayscale image (gray value gives depth information). I start with a three channel image of 32bit floats with each pixel ...
171 views

### what kind of information we can get if the auto-correlation for an image is a ring or two rings?

I did the auto-correlation for an image by Mathematica. The auto-correlation function shows rings as follow..I am sorry that I can not attach the original image here. From the following auto-...
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### Amplitudes and phases of transform of an image

I have recorded an image of a large macromolecule and after several types of image analysis, have obtained a rotationally averaged image, that is not quite perfect, but appears to show 6-fold symmetry....
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### How does Arbib's clustering method work?

Recently in Image Processing I've been studying image clustering (or segmentation) methods and one of them is Arbib's. I understand the main idea behind it from which you start with one cluster with ...
152 views

### Saddle points, Nodes and Edges definitions

I am working on some algorithm implementation, however being new to image processing, I have some questions about some of the definitions used. UPDATE: for those asking for more information, this is ...
764 views

### Distinguish between 2D and 3D objects according to depth

I'm trying to distinguish by code between a real 3D object and its picture - a 2D object, based on depth information. However the picture (= the 2D image) might be captured from noisy background, so I ...
209 views

### How do I deal with occlusion, warping, or perspective distortion for object detection

I am using SIFT features for detecting logos in clothes. SIFT is quite powerful, as it is scale invariant, but how do I deal with the problem of occlusion and warping? More specifically, the logos in ...
189 views

### Creating a texture image from existing image

I have some unusual question. I have searched online and couldn't find something similar to what I want to achieve. I have an image, and I want to create a new image from it (in the same size), so ...
523 views

### Estimate Image power spectrum of the noise

I want to implement Wiener filter. I have original image and image blured with linear motion. The one thing I am lack of(to implement it) is Noise power spectrum. I know that it is hard task. I've ...
126 views

### How do i detect if an image has a gradient or not?

I have coloured images, some may be just clipart, some may be artwork, both could be with or without gradients. Before i run a colour counting algorithm on them, i want to detect if the image has ...
2k views

### Why Normalized Cross Correlation Score of different templates is high?

I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
66 views

### What equation describes black alpha on a white image?

What equation best describes the alpha content of a black colored pixel applied to a white pixel when measuring the resulting pixel intensity? For instance given a white pixel: argb : 255, 255, 255, ...
1k views

For those who have either used Picasa/Photoshop, they would see different image enhancement options such as: Change exposure Change shadow Change highlights Change vibrance I have searched online a ...
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### High Pass Filter, effect of applying it on this image.

I am having question about the HPF. In particular, it is having a high pass guassian filter which is applied to the original image below. High pass filter should only detect edge (lots of change in ...
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### Image Processing - Identifing/locating Random Solid Blocks of Colour

I am not overly familiar with image processing. I know a little about it from University, but I have not really done any for a while and I have found myself with a problem that requires it. What I ...
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### Understanding a mathematical statement in image processing

I am reading a document on Image processing and couldn't analyze a statement in it. For any $k \in \Psi_s$, the family of values $\{u[\varphi(p+l)+k-l]:l \in \Psi_s \}$ is representative of the ...
52 views

### Best method for texture classfication

I am working in medical and nature images processing . I want to find a popular method to segment texture image. Could you suggest a popular method to do it? For example: Gabor filter, tensor...
157 views

### What is purpose of correlation kernel? IIs it high pass filter or low pass filter?

I am research about correlation kernel and I have some questions that need your help. Let see the pp. 3302-3303 in the paper: Changyang Li, et al., Robust Model for Segmenting Images With/Without ...
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### How to store generated eigen faces for future face recognition?

My code works in the following manner: 1.First, it obtains several images from the training set 2.After loading these images, we find the normalized faces,mean face and perform several calculation. ...
1k views

### How to perform a Stockwell Transform on a 2D matrix

I was looking at performing a Stockwell transform on a matrix (or an image as it has two directions - the matrix I am interested in has a spatial dimension and a time dimension, but this should make ...
1k views

### What are the various techniques for detecting Walls in the Building(Architectural) floor plan Images?

I have to process building floor plan images to extract Walls from the structure. It is trivial in case of binary images; but the images in our case are colored, and each have different color of walls....
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### How many way to reduce overfitting problem of Linear classificationH

I am working in linear classification such as y=ax+b. where x={x1...xn}. But the method has weakness that is overfitting problem. Could you suggest to me one method or one way to reduce overfitting ...
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### How many features of given image

assume that I have a set of image and segmented image of a object in image (training set). Now, I want to measure features of object in image based on the training data. But I don't know how many ...
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### Matching 2 undirected weighted graph in matlab

Consider 2 undirected weighted graph as shown in figure.Consider first graph as G1 and second graph as G2.Graph G1 consist of vertices V={F1,F2,F3,F4,F5} and Graph G2 consist of vertices V={N1,N2,N3,...
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### Please suggest me good algorithm for video segmentation based on changing background?

Iam having 1 min video.I need to cut the video into 5 segments depending on changing background.Please suggest me good algorithm which can be easily implemented in matlab.Please provide me helpful ...
51 views

### Pedestrian Re-identification during tracking

During the multi-camera tracking, there is a situation where one person moves from one camera's coverage area to another. In that case that person has to be re-identified(as the one from previous ...
192 views

### Optimal way for curve detection

I am totally new to image recognition and image analysis and have a project concerning detecting a smooth curve on a uniform background (white/black/any color) and then be able to follow this curve ...