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.

505 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
0
votes
1answer
310 views

Programming the IDWT for image processing

I want to program the 2D inverse discrete wavelet transform (only 1 level) in the case of image processing. In the matlab website there's this diagram: now, I want to program the IDWT with haar ...
0
votes
0answers
94 views

How to overcome effect of intensity variation in image processing?

I want to process an image for which I need the method to be robust to lighting conditions. For that the only thing I can think of is normalising intensity. I did this by dividing the image with ...
0
votes
0answers
493 views

Convex hull area in pixels

I am calculating different attributes for connected regions of the image, with the final goal of classification. One of the attributes I am working with is a sparsity measure, calculated as the ratio ...
0
votes
1answer
509 views

The Kernel in the Guided Image Filter

I am trying to understand how to calculate kernel matrix for guided image filter. Following is the formula for kernel calculation. where k is window withing pixels i and j belong i assumed that ...
0
votes
0answers
40 views

Simple technique to segment out optical disk and vessels from retinography

I'm looking for simple techniques to segment out the optical disk and vessels from a retinography. By simple I mean using techniques taught during an introductory course on Digital Image Processing. ...
0
votes
0answers
185 views

How doesn't JPEG huffman table contain 256 codes?

Here are the DHT entries I got from JPEG snoop: ...
0
votes
0answers
32 views

Kalman Filter - Gaussian representation

I'm trying to understand well the kalman filter, as a result i'm having this question : Why do we represent noise with a Gaussian ? what does this really mean intuitively ?
0
votes
0answers
513 views

How can l extract characters withe same bounding box size?

l have a set of images which represent a sequence of characters. l'm wonderning whether OpenCV can segments and crop each character from the image with same bounding box size. My numbers are not ...
0
votes
0answers
122 views

How to distort a signal (image) pattern using bilinear interpolation

I have a signal pattern $s$ that generated at time $t$ like this: $$ s(x,y,t)=D(x,y)\sin(\omega t-0.56) $$ Where $D(x,y)$ is a mode shape, calculated by $$ D(x,y)=a\left\{\left(\frac{x}{m}-0.55\right)...
0
votes
0answers
42 views

Looking for a file format for lane detection

I am trying to extract lane boundary lines from two recorded video cameras on the sides of the vehicle. I would ultimately like to calculate lane position from those boundaries. My thought process is:...
0
votes
0answers
53 views

Question about central spatial moments

Spatial moment $$ m_{pq} = \sum_{(x, y)\ \in \mathbb R} x^p y^q I(x, y) $$ The order of each moment is $p+q$. Central moment $$ \mu_{pq} = \sum_{(x, y)\ \in \mathbb R} (x - \bar x)^p (x - \...
0
votes
2answers
1k views

Segmentation of warped text lines

I am trying to segment warped text lines found in photos taken from a page of a book (from the camera of a smartphone). This is meant as a preprocessing step before running OCR on them. I have found ...
0
votes
0answers
473 views

Segmentation and edge linking

I am trying to implement segmentation on an image. after a difference of Gaussians Process and applying weights to my edges I want to go through edge linking by local processing. I have seen this ...
0
votes
1answer
143 views

Image Processing- ornament detection

So I am working on a project where we are supposed to detect and count the red and gold ornaments in the picture provided in the link below. I am having issues detecting and counting each ornament and ...
0
votes
0answers
499 views

Image reconstruction using Laplace pyramid

Given a sub-sampled Image $P_n$ belonging to layer $n$, a Gaussian kernel $G$ and a Laplace Layer $L_{n-1}$ of layer $n-1$, my efforts to create $P_{n-1}$ of previous layer $n-1$ have failed. This ...
0
votes
0answers
29 views

Identifying who is who - Image processing

I am working on a problem where I have to find how many people are passing through a point and how many times they pass through. A good example use case for this problem would be counting how many ...
0
votes
1answer
158 views

Homography Matrix Correlations

If the homography matrix of Image 1 to Image 2 is given, and another homography matrix for image 2 to image 3 is given, how do I calculate the homography matrix for image 1 to image 3? PS : I need the ...
0
votes
1answer
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: ...
0
votes
0answers
264 views

Prediction-error filter for images

I am interested in studying local pixel value dependencies in images and I am wondering if it exists a general form of prediction-error convolutional filter that is able to suppress the image's ...
0
votes
0answers
75 views

Which is faster: image segmentation or line detection?

Some papers use image segmentation techniques and others use edge detection. I need to know which one is faster. update: I need to do semantic segmentation for outdoor sense and the data is optical ...
0
votes
0answers
110 views

MATLAB: Normalize Image in Frequency Domain

I have 3 different images and I have the data which is in frequency domain. The data size is : 192x256x88x32x3. ...
0
votes
0answers
623 views

Average gradient of pixels and sum of absolute diference

Studying the research paper Multidirectional Scratch Detection and Restoration in Digitized Old Images, E. Ardizzone et al., 2011: I have several questions regarding this section (5. Restoration), ...
0
votes
0answers
68 views

Enhancing very thin lines in images

I want to detect filopodia (red arrow indicates filopodia in a vessel image). My strategy is that if $I$ is the original and $J$ is the another image after opening operation. Then, $I-J$ is the ...
0
votes
0answers
170 views

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}+\...
0
votes
0answers
258 views

circle or arc recognition in noisy image

I have an image that is missing the center and contain what seems to be two parts of circles or maybe two arcs. What is a good metric or signal processing approach to use to differentiate between the ...
0
votes
0answers
51 views

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 ...
0
votes
1answer
472 views

How to use the Walsh-Hadamard transform to filter 24 bit RGB color values in a localized spatial region?

After reading this Signal processing Stack Exchange article tonight, What is the Walsh-Hadamard Transform and what is it good for?, I became interested in applying the Walsh-Hadamard transform to ...
0
votes
0answers
39 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 ...
0
votes
0answers
308 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 ...
0
votes
1answer
247 views

compression algorithm

Steganography can hide one image inside another. If we have a compression algorithm that allows us to fit the bits for two images into the size of one, can we think of a way to modify a run-length ...
0
votes
2answers
461 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 ...
0
votes
0answers
31 views

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 ...
0
votes
0answers
56 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 ...
0
votes
0answers
37 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. ...
0
votes
0answers
287 views

Head pose estimation

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 ...
0
votes
0answers
230 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?
0
votes
0answers
510 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 ...
0
votes
0answers
336 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 ...
0
votes
0answers
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 ...
0
votes
0answers
83 views

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 ...
0
votes
0answers
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 ...
0
votes
0answers
73 views

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
0
votes
0answers
46 views

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 ...
0
votes
0answers
107 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 ...
0
votes
0answers
185 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 $E = E_s + λE_c$, for different situations that try to ...
0
votes
2answers
310 views

Image processing for eye movements

I have series of images extracted from a eye tracker video for both eyes. is there any image processing algorithm/method/technique available to find the following from those images: Horizontal eye ...
0
votes
0answers
101 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 ...
0
votes
0answers
473 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 ...
0
votes
1answer
597 views

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 ...
0
votes
0answers
168 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-...