Questions tagged [opencv]
OpenCV (Open Source Computer Vision) is a cross-platform library of programming functions for real time computer vision.
354
questions
0
votes
0
answers
26
views
How to detect a line from a broken line segment in video?
I am trying to detect meteors in a video, and so far, what I did.
Preprocessing: changing to grayscale and morphological operations like dilation and erosion.
background subtraction method
adding ...
- 129
4
votes
1
answer
302
views
OpenCV 2 Connect Incomplete Contours edges
I have to connect the unfinished edges of the contours in the red color bounding box.
I used distance transform, watershed, and morphology, but still, edges are not connecting.
...
- 41
0
votes
1
answer
158
views
Laplacian Filter kernel size meaning
I'm using laplacian filter in opencv.
I usually use laplacian filter with kernel size 3 which is default setting in opencv.
I'm just curious what happen(intuitively) when I choose bigger size kernel?
...
- 33
2
votes
1
answer
89
views
Camera sensor artifacts next to edges in calibration images; what is causing these?
I am trying to image some ChArUco targets using a monochrome machine vision camera with a CMOS sensor and the attached images show the artifact I am observing:
2-pixel-wide bright vertical streaks ...
- 41
0
votes
0
answers
61
views
OpenCV canny vs my own C++ version - high difference
I have implemented my own canny edge detector in C++. If I compare the result with the same thresholds to OpenCV (cv::Canny(img, res, 50, 100)), the difference is ...
- 113
2
votes
1
answer
235
views
Can DFT magnitude be used to identify repeating patterns in an Image?
Given the DFT magnitude vector of an 1-D image, I want to understand if we can calculate the size and pitch of repeating patterns in the image. Is this possible? I took a few test images and ...
- 73
3
votes
1
answer
59
views
Fingerprint enhancement lighter version
I've been advised to ask here, I hope that it fits.
Original question:
I want to create a more straightforward and lighter version of this fantastic repo (which itself is based on Fingerprint Image ...
- 131
0
votes
1
answer
204
views
1
vote
0
answers
72
views
Segment Hand Image into Palm and Fingers
Here is my code, i want to extract only the fingers and save them as a new image
...
- 11
0
votes
0
answers
15
views
Detect Cyclinderical Shape of İmage Signal
I want to detect lid of barrel is open or not in image. For this , I'm thinking of using deep learning and ı am colleting data. Besides, instead of inserting the picture directly into the deep ...
2
votes
1
answer
1k
views
Implementation of Wiener filter to deblur an image using Python and OpenCV
EDIT: I have debugged the runtime warning, and now I am able to get an output image. However, the output image is still blurry. Increasing the constant value heavily distorts the image. Setting ...
- 21
3
votes
1
answer
2k
views
Removing white reflective pixels from scanned RGB image (Python - preferably OpenCV)
The images above are tiles taken from a scanned painting. It's easy to see where there are tiny reflections scattered throughout. I wish to remove (or diminish) the tiny reflections somehow, across a ...
- 161
1
vote
1
answer
184
views
Problem with "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki Abe
I have a Problem with the Paper "Topological Structural Analysis of Digitized Binary Images by Border Following" by Suzuki and Abe.
In the Chapter "Appendix I: The Formal Description of ...
- 11
0
votes
1
answer
221
views
Finding rectangle corners by using point cloud
I have a rectangle in the 3D scene, which I know its width and height. It is placed in the 3D scene like the image below. I can manually select all points on the rectangle by mouse click.
Given the ...
- 103
3
votes
2
answers
366
views
Which Blur is being used in this effect
I'm trying to recreate an effect used on photoshop called satin effect, which has an option that control the size of the satin, which I think it's just a special blur applied to the satin pattern
So ...
- 71
2
votes
0
answers
33
views
How to achieve uniform gaussian profile? Beam profile has grainy/multimode pattern
Hi apologies in advance if this (optics & image-process) is not where I should post this question. Thanks for the help!
I'm required to make a jig that measures the divergence angle of a ...
- 21
2
votes
2
answers
144
views
What happens when you read and save the same JPEG image again over and over?
This question is mostly related to jpeg compression and expected results when you read and save the same jpeg file several times.
Let's say you have read an uncompressed image (originally it has never ...
- 254
1
vote
1
answer
256
views
What does the last row of a homography matrix mean?
I have used the MOTION_HOMOGRAPHY function in OpenCV (python3.6, enhanced correlation coefficient) to register a pair of images, and I am trying to interpret the 3 x 3 warp matrix the function returns:...
- 119
3
votes
2
answers
801
views
Detecting bullet holes using Python with camera or sensors
I am trying to build a system to detect bullet holes in paper. I've read many StackOverflow threads but not a single one satisfied me. Current methods, which I am using, are good but not perfect and ...
- 31
0
votes
1
answer
104
views
How can I segment areas, each of which has nearly same colors of pixels in an image?
For clarity, Nearly same colors of pixels belong to a category. Another nearly same colors of pixels belong to another category. The distinction depends on nearly same RGB values of pixels.
- 11
3
votes
0
answers
75
views
Overall approach for building a footfall/age/gender counter using CCTV footage
I would like some advice to validate my approach for building a computer vision system.
Design brief:
Using existing CCTV cameras in a retail store, detect the footfall in the shop (count individual ...
- 31
0
votes
1
answer
73
views
Feature Extraction for Image Classification of Vegetables and Fruits Using Classic Computer Vision Techniques
I don't know if this is the right place to ask this but lets go. I am a beginner in computer vision and I have a project of fruit recognition based on Kaggle's Fruit 360 dataset. I know that CNNs are ...
- 111
2
votes
1
answer
131
views
bilateral filter for color images
Fast Bilateral Filter
I came across the above code of the bilateral filter for grayscale images. I tried to implement it for color images by splitting the image ti BGR channels and applying it to each ...
1
vote
2
answers
568
views
Calibration using Camera Calibration Toolbox for Matlab vs OpenCV
I am currently working to calibrate a camera and I tried using both the Caltech Camera Calibration Toolbox for Matlab and OpenCV. I used the same images for both methods. Even if the error seems to ...
0
votes
0
answers
240
views
Find vertical/horizontal lines
I tried everything including the Hough Transform with different inputs; Laplacian and Sobel and Canny edge detector were run on filtered image but cv2.HoughLinesP and cv2.HoughLines both give me wrong ...
- 1
2
votes
1
answer
1k
views
OpenCV: Can't find large rectangle contour
I'm trying to re-create the dimensions of an object by setting it up on a grid and taking as close to a top-down photo I can which I will then get the contours of the largest bounding rectangle and ...
0
votes
2
answers
3k
views
Is there a way to find the contours of instances in a binary mask image by color?
I need to find the contours for each of the instances of microscopic cells in a binary image mask of dimensions 256 x 256 shown below.
My approach involves thresholding the image to get a binary mask ...
1
vote
1
answer
246
views
How to remove dark shadows from camera capturing when combining LED spots and ambient light
I'm getting strange moving shadow strips on my camera capture during a computer vision experiment:
As the gif image above shows, those strips move to bottom slowly. I have also noticed that it ...
- 111
5
votes
1
answer
276
views
How to detect rectangular images inserted into another image?
It's just for a simple binary classification, so it's not needed to find the location of the inserted image or the content. I'm only interested in checking whether something like that is present or ...
- 153
4
votes
1
answer
418
views
How to Remove Double Lines Detected Along the Edges by Edge Detector?
I'm trying to take real time input for hand gestures with web cam, then processing the images to feed them to a neural network. I wrote this processing function to make the hand features look ...
- 145
0
votes
1
answer
242
views
image processing find liquid level (only with images processing, no AI)
I want some ideas to get the level of a water/liquor in a cup. i tried many ideas (contours, edges,...) but nothings is working. So any ideas that i can explore.
0
votes
1
answer
29
views
Morphological operations to isolate and preserve network graph structure?
Suppose there is an image with long, connected lines which form connected, closed cycles in an image.
Is there a standard morphological approach to isolate only the lines, and drop all other pixels?
...
- 115
0
votes
1
answer
69
views
What is the function of init in Active Contour Model
In practice of image processing using scikit-image, I didn't understand the role of constructing init numpy array in Active Contour Model example. Is it the red section drawn in the example astronaut ...
- 103
1
vote
0
answers
391
views
2D Deconvolution using a non-gaussian mask using C++
I am currently working on a project, where we record an electron beam profile using a target. The obtained image is a result of convolution of the actual beam profile and the aperture wherein the ...
- 11
0
votes
1
answer
96
views
Suggestions for creating 3D Bounding Boxes of Books on a Shelf from RGB-D Images
I am new to image processing, so I beg your pardon if this is a trivial question. I am trying to use an RGB-D camera to detect 3D bounding boxes of books on a shelf.
Here are some examples of possible ...
0
votes
0
answers
89
views
Find camera tilt
If I have a camera that captures tilted images what is the way to find the tilt of the camera? Is there a pattern that I can photograph or something similar. I want to reduce the tilt as precisely as ...
- 9
2
votes
0
answers
131
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,...
- 283
0
votes
1
answer
135
views
Harris corner detection shape of $E(u,v)$
I am taking a computer vision class and I have just learnt about the Harris corner detection concept. A corner is detected when a small shift in a window function defined around the corner results in ...
- 283
0
votes
0
answers
470
views
Extracting articles from epaper into individually cropped image
I want to segment the image below (click for bigger image) into columns based on the natural gaps that exist in the columns. The article columns should be perfectly vertical and need not be the same ...
1
vote
0
answers
213
views
What is the order of the output of HoughCircles in OpenCV, when having several circles on a frame?
So I am trying to use stereo vision to calculate the depth of several red balls. With the function HoughCircles, I get an output at one frame from one of the cameras like for example:
...
- 11
1
vote
0
answers
176
views
Fisheye Lens Calibration for precision
OpenCV library offers a fisheye calibration method. I have looked at the code and looked at some papers and still don't understand how it works completely. The reason why I am interested is following:
...
- 9
0
votes
0
answers
2k
views
How can i get Celsius/kelvin temperature from a thermal image in python language?
How can I convert RGB values of the thermal image into Celsius or kelvin temperature in python?
Here is the thermal image taken by a FLIR device:
Here I am reading image using OpenCV and getting the ...
- 1
5
votes
0
answers
1k
views
Is rotation of a Fourier transform the same thing as Fourier transform of a rotation?
I'm working on an image processing problem and wondering if DFT(rotation(image)) == rotation(DFT(image)) (1). My final goal is to apply rotations in the Fourier domain then do an inverse Fourier ...
- 163
0
votes
1
answer
48
views
Low samples numbers machine vision training for object detection
I'm trying to set-up a machine vision application in which I have to detect the position of a printing nozzle (in the red sqaure in the image) in a field of view in order to prcisely position a ganty ...
3
votes
2
answers
598
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 ...
- 131
0
votes
1
answer
844
views
Why we have to multiply the images with $(-1)^{x+y}$ to center the transform in frequency domain filtering?
To perform the filtering infrequency domain we perform multiplication of $(-1)^{x+y}$ why??
- 131
0
votes
1
answer
560
views
How the Grayscale images are converted back to RGB?
In case of RGB to grayscale conversion we take the average of R,G,B channels and convert them to Grayscale which has songle channel. How to convert back the Grayscale to RGB ??
- 131
0
votes
0
answers
231
views
Use sparse optical tracking to track a Bounding Box object
I need some help on solving this issue. Any tips are appreciated.
The goal of the project is to try to track a Bounding Box object, chosen arbitrarily in an image, throughout many frames of a ...
0
votes
0
answers
364
views
Calibrating cameras with different resolutions
I have two cameras with very different resolutions. One camera is the RGB camera of the microsoft kinect sensor with a resolution of 1920x1080 and the other one is ...
- 101
2
votes
1
answer
320
views
Salt and Pepper impulse Denoising opencv
I am creating a generic method to work on salt and pepper noise and variants. The example images are as shown below :
I tried few methods, such as
...
