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.

544 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
6
votes
0answers
92 views

Converting very short “motionless” video frames to single, better-resolved, images

I made a mistake with my newly bought compact camera, before a trip to Japan. Instead of taking single pictures, I ended up with a few short "MP4" video files (1 second, 2-3 frames). I could ...
6
votes
1answer
285 views

Analytical Expression for Convolution of Two 2D DFTs

I am trying to do an image analysis problem on some images, and I want to calculate some things in the frequency domain which are giving me problems. Say I have an (discrete) image $I(x,y)$ of size $...
5
votes
0answers
162 views

Residual error when setting measurement matrix in compresssive sensing

I have an issue when implementing compressive sensing to recover sparse vector. Assume I have sparse vector $x$ of length, for example, $(256,1)$. $x = [x_1,x_2,.....x_{256}]$. This vector is ...
5
votes
1answer
311 views

Detect quasi-parallel lines with spurs in a binary image

I'm looking for a way to remove quasi-parallel curves from the net, as depicted in the figure. Not only the original nets (upper row in figure) contain many spurs, but also the curves to be detected ...
4
votes
0answers
61 views

Approaches to Segmentation in images of water surface

this is my first question here. Therefore please help me inform me when I miss any good practice in asking questions here. Given a short video sequence of an water surface, I would like to detect if ...
4
votes
1answer
223 views

Image Segmentation - Comparing GrabCut Method vs. Level Set Method

Checking the literature about image segmentation, if I am not wrong, there are two main approaches: Variational approach e.g. level-set optimization in Chan-Vese Combinatorial approach e.g. using ...
4
votes
1answer
3k views

What is a good distance measure for matching SIFT descriptors depending on the distribution of their noise?

I have read some papers about distance measures like Euclidean, Manhattan or Chi-Square for matching gradient based image descriptors like those computed from the SIFT Algorithm (128-D vectors). Most ...
4
votes
0answers
485 views

How to construct descriptors for irregularly shaped image patches

As hinted in this answer, Perceptual hashing is a way to ascribe comparable measures (hashes) to images (rectangular patches). The images do not need to be the same size, and can be slightly distorted,...
3
votes
1answer
100 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 ...
3
votes
2answers
91 views

How do I denoise a microscope image?

I'm working in a computer vision project, where the goal is to detect some specific parasites, but now that I have the images, I noticed that they have a watermark that specifies the microscope ...
3
votes
0answers
679 views

Correct Fish Eye camera Radial Distortion and blurry effect at the image edges

There are a lot of questions regarding this topic ,but I am trying to get a more clear picture from these questions. I am trying to calibrate a fish eye camera and I am using OpenCV omnidir class ...
3
votes
1answer
4k views

Improving Canny Edge Detection and Contours Image Segmentation

I am working on an image segmentation project to identify playing cards on varying backgrounds. For my use case I care most that I accurately extract all the cards in the image; false-positives are ...
3
votes
0answers
121 views

How to replace color in an image without changing its texture/shades or brightness?

I want to replace color in an image from another color: For that sample image is below I want to replace color such that it becomes I know it can be easily done in Photoshop but I am looking for an ...
3
votes
0answers
8k views

Horizontal banding (flickering) due to electronic rolling shutters

It is a well-known artifact that in CMOS cameras with electronic rolling shutter, horizontal banding (flickering), i.e. brightness intensity variations, are observed when the image is recorded under ...
3
votes
0answers
488 views

Box filter approximations for oriented gabor filters

I'm currently working on a library to generate synthetic fingerprints using the SFinGe method (by Maltoni, Maio and Cappelli) link :http://biolab.csr.unibo.it/research.asp?organize=Activities&...
3
votes
0answers
569 views

Interpolating on the borders of differently-resolved images

I'm creating a three-dimensional model of the earth based on SRTM height data. The data set is pretty huge, so only a small fraction of the data is available at any given time. The height data is ...
3
votes
0answers
1k views

Why PSNR decreases for Ultrasound Images?

I am working different types of filters to remove speckle noise in ultrasound image. I have taken the below paper as my base paper and trying to reproduce the results of this paper: My Base Paper I ...
3
votes
0answers
2k views

Creating a Gaussian Pyramid

I'm trying to recreate a gassuain pyramid using the following scales: There seems to be two concepts used here: 1) When an image is halved, applying a gaussian kernel of σ will apply as 2σ. 2) When ...
3
votes
0answers
864 views

Any Good Image Blind Deconvolution Algorithm for Removing Camera Shake

I am working in digital image restoration field, i have images that are degraded by camera shake.. can anyone please suggest me any better non blind deconvolution algorithm. my images are similar to ...
3
votes
0answers
108 views

Perceptually Corresponding Error Map

Is there any better measurement of error between two images than just taking pixel value differences? The problem I am tackling is stitching images containing "sensitive" objects, such as moving ...
3
votes
0answers
87 views

blur PSF modeling for small stright camera movement

I am interested in reovering images affected by blur of known orientation and known span. Camera movement during capture is very small, blur span is of about 0-4px. What is the most accurate way to ...
3
votes
0answers
206 views

Blurring in anisotropic outputs

I am trying to produce ideal anisotropic diffusion outputs using the standard lena image. Using the first coefficient , the output is coming somewhat close to ideal ouput but when I increase the kappa ...
2
votes
0answers
28 views

Taylor series approximation in Harris corner detection

While watching through the computer vision lecture on interest point detection, computing $E(u,v)$ requires computing the quantity $$E(u,v) = \sum_{x,y}(I(x+u,y+v) - I(x,y))^2$$ In the lecture, $I(x+u,...
2
votes
1answer
40 views

How virtual ads work in stadiums?

I was looking at a technology which enables virtual advertisement on the perimeter ads in soccer. It's relatively an old technology for a few years back, but I'm surprised to see the quality of it. ...
2
votes
0answers
54 views

Processing Multiple Images to Detect Moving Object in Low SNR Conditions

I am new to this forum and new to the use of Fast Fourier transforms although I can program in Python 3 a bit. I have an unusual question and am seeking some general advice on (a) whether what I am ...
2
votes
2answers
119 views

what is the difference between the convolution and differentiation over image in image processing?

In image processing the differentiation and convolution are the terms that are used interchangeably. What is the difference between applying convolution and differentiation over the image? How we ...
2
votes
2answers
90 views

Why are 8 points needed to compute a fundamental matrix?

Homograpies have 8 degrees of freedom. Fundamental matrices have 7. Essential matrices have 5. To the best I could find, all those matrices are obtained by using the 8 point algorithm. I don't see ...
2
votes
0answers
21 views

Array bounds check o(1) (Integral image?)

Not sure if this is the correct place to ask but I have a question about techniques for processing an array of pixels with o(1) complexity. That is to get the sum of a subset of an array but if this ...
2
votes
0answers
92 views

Combining two images with different resolutions?

I am attempting to combine two radar images, each of which is a 3-dimensional cube with a range dimension, an azimuth angle dimension, and an elevation angle dimension. One image has high azimuth ...
2
votes
1answer
135 views

What impact have different types of border-handling on high pass or low pass filtering?

When high or low pass filters are being applied to an (grayscale) image, the borders need to be handled separately. They could be filled with 0's or 255's (b/w), repeat the nearest pixel value, or ...
2
votes
1answer
60 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, ...
2
votes
0answers
65 views

How does the “additive operator splitting” exactly work?

I am reading about the non-linear (or non-homogenous) diffusion method (aka anistropic diffusion method). There are several ways of implementing this method. In all cases, we first need to discretise ...
2
votes
0answers
291 views

How do 2D DCT basis functions interact to produce 8x8 JPEG tiles?

This section is a bit of an intro. If you want to skip directly to where the problem is explicitly outlined, skip to the bottom of this post. Please note that I'm not hip with mathematical lingo, so ...
2
votes
0answers
94 views

How to calculate Walsh hadamard transform for image patches of odd sizes?

I was reading this paper on optical flow, which as apart of the algorithm makes use Walsh-Hadamard transform on image patches of size 2r+1. So far, where ever I have looked, I could only find that ...
2
votes
0answers
192 views

Intuitively, why is the comb function the sampling function?

The comb function can be used to sample a continuous signal. The comb function is defined as follows $$ C_T(t) = \sum_{k=-\infty}^{\infty} \delta(t - kT) $$ where $\delta$ is the Dirac function, ...
2
votes
0answers
560 views

How do piecewise affine transformation work?

How can piecewise affine transform be used to warp an arbitrary collection of input landmark coordinates to a corresponding set of base coordinates? Can anyone give any physical examples, the book I ...
2
votes
1answer
2k views

How can I detect pipeline cracks using OpenCV and Python?

I have developed a robot that captures images of the pipeline interior as it moves. The requirement was to be able to detect cracks inside. So far i tried several OpenCV codes that find the crack ...
2
votes
2answers
177 views

Fast Morphological Erosion / Dilation with Variable Window Size

I want to perform the following operation on an image: consider a square window around every pixel, find the maximum value in this window, and replace the central pixel value with this maximum value. ...
2
votes
0answers
210 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 ...
2
votes
0answers
59 views

Mid-point of worm-like objects

I have a video of worm-like objects which move. They can move in a straight line, they can rotate in circles, they can move in a serpentine/winding/sinuous way. I need to track them. I already have ...
2
votes
0answers
185 views

Is it possible to calculate the optical flow magnitude for rigid motion?

For objects in 2D plane, it is pretty simple to calculate the displacement vectors using optical flow algorithms such as SLIC, LK, Färneback etc. But how it is possible to know the magnitude of the ...
2
votes
1answer
127 views

What motion estimation techniques that could estimate the motion of every pixel?

I'm trying to estimate a motion from a video, however based on my finding, those methods usually meant for large motion and sparse in nature. Optical flow: Sparse and fail to detect sub-pixel motion ...
2
votes
1answer
118 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 ...
2
votes
0answers
54 views

Determining Optic Flow - Horn and Schunck - robust/insensitive to …

Can somebody explain to me why the Horn and Schunck algorithm (probably mostly the smoothness constraint) is robust to image sequences that are quantized rather coarsely in space and/or time. (Thought ...
2
votes
0answers
131 views

How to use FIR with Kaiser windows for 2D image

I am trying to use FIR filter (opensource codes from iowa hills software) as low pass filter, kaiser window, to filter 2D image. Does someone can guide me that how can I do that? I am able to obtain ...
2
votes
0answers
58 views

What Techniques Are Used for Signal / Image Denoising (Example Image Provided)?

I have an image that looks like this (it might appear low res in a browser because it is 16 MB). This image was taken with a scanning electron microscope, but because the equipment is outdated there ...
2
votes
0answers
291 views

stones' detection in jewel image

The project I am doing is to detect stones in an image of a jewel, so as to get the idea of the deduction to be made in the gross weight of the jewel. I have done image-segmentation in the HSV color ...
2
votes
0answers
64 views

Mesuring the distance between a base line and an object

I am working on an image having musical symbols, like Before i reach this step i have removed the staff lines to recognize them in efficiency. but now i want to detect on which stave line they exist. ...
2
votes
0answers
334 views

Find best fitting rectangles after applying edge detection

I am trying to implement a box detection algorithm. In my pipeline, I start with image warping to simulate a frontal view of the shelf containing the boxes (assuming boxes are straight in that ...
2
votes
0answers
210 views

algorithm for segmenting cheese microstructure

I'm trying to get the internal geometry of cheese from images of its microstructure: I tried the canny edge detector and otsu thresholding but neither of these worked very well. I'm guessing that I ...

1
2 3 4 5
11