Questions tagged [opencv]
OpenCV (Open Source Computer Vision) is a library for real time computer vision. When using this tag, please add a language specific tag (python, c++, ...), if relevant.
opencv
8,924
questions
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OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection
I successfully implemented the OpenCV square-detection example in my test application, but now need to filter the output, because it's quite messy - or is my code wrong?
I'm interested in the four ...
- 12k
118
votes
10
answers
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Choosing the correct upper and lower HSV boundaries for color detection with`cv::inRange` (OpenCV)
I have an image of a coffee can with an orange lid position of which I want to find.
Here is it .
gcolor2 utility shows HSV at the center of the lid to be (22, 59, 100).
The question is how to choose ...
- 1,383
166
votes
14
answers
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OpenCV in Android Studio
I want to use OpenCV library in my app with Android Studio. I followed instructions found here but I get error
Configuration with name 'default' not found
What can be wrong?
I use Android Studio ...
- 4,451
415
votes
12
answers
1.0m
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How to crop an image in OpenCV using Python
How can I crop images, like I've done before in PIL, using OpenCV.
Working example on PIL
im = Image.open('0.png').convert('L')
im = im.crop((1, 1, 98, 33))
im.save('_0.png')
But how I can do it ...
- 4,453
37
votes
3
answers
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Setup OpenCV-2.3 for Visual Studio 2010
I'm trying to use opencv 2.3 with Visual Studio 2010 Express. My code is from example:
#include "stdafx.h"
#include <highgui.h>
int _tmain(int argc, _TCHAR* argv[])
{
int c;
// ...
- 3,659
457
votes
26
answers
2.2m
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Cannot find module cv2 when using OpenCV [duplicate]
I have installed OpenCV on the Occidentalis operating system (a variant of Raspbian) on a Raspberry Pi, using this script by jayrambhia. It installed version 2.4.5.
When I try import cv2 in a Python ...
- 4,603
428
votes
3
answers
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Simple Digit Recognition OCR in OpenCV-Python
I am trying to implement a "Digit Recognition OCR" in OpenCV-Python (cv2). It is just for learning purposes. I would like to learn both KNearest and SVM features in OpenCV.
I have 100 samples (i.e. ...
- 52.5k
169
votes
10
answers
133k
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Extracting text OpenCV
I am trying to find the bounding boxes of text in an image and am currently using this approach:
// calculate the local variances of the grayscale image
Mat t_mean, t_mean_2;
Mat grayF;
outImg_gray....
- 3,078
217
votes
6
answers
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How to remove convexity defects in a Sudoku square?
I was doing a fun project: Solving a Sudoku from an input image using OpenCV (as in Google goggles etc). And I have completed the task, but at the end I found a little problem for which I came here.
...
- 52.5k
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23
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Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition
One of the most interesting projects I've worked on in the past couple of years was a project about image processing. The goal was to develop a system to be able to recognize Coca-Cola 'cans' (note ...
- 41.2k
231
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12
answers
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Is there a way to detect if an image is blurry? [closed]
I was wondering if there is a way to determine if an image is blurry or not by analyzing the image data.
- 4,857
35
votes
3
answers
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How can I define a threshold value to detect only green colour objects in an image with Python OpenCV?
I want to detect only green objects from an image captured in a natural environment. How can I define it?
Because in here I want to pass the threshold value, let's say 'x'. By using this x, I want to ...
- 359
130
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24
answers
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ImportError: DLL load failed: %1 is not a valid Win32 application. But the DLL's are there
I have a situation very much like the one at Error "ImportError: DLL load failed: %1 is not a valid Win32 application", but the answer there isn't working for me.
My Python code says:
import ...
- 27.8k
205
votes
6
answers
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Checking images for similarity with OpenCV
Does OpenCV support the comparison of two images, returning some value (maybe a percentage) that indicates how similar these images are? E.g. 100% would be returned if the same image was passed twice, ...
- 8,801
38
votes
6
answers
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Detect semicircle in OpenCV
I am trying to detect full circles and semicircles in an image.
I am following the below mentioned procedure:
Process image (including Canny edge detection).
Find contours and draw them on an empty ...
- 977