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Questions tagged [vision]

Methods to acquire, analyze and understand images using mathematical approaches.

664 questions
114
votes
6 answers

What is the mAP metric and how is it calculated?

In Computer Vision and Object Detection, a common evaluation method is mAP. What is it and how is it calculated?
cerebrou
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32
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4 answers

Is it possible to run opencv (python binding) from a virtualenv?

I would like to keep everything contained within the virtualenv. Is this possible with OpenCV? I'm fine with building from scratch, do I just need to setup the virtualenv first then use special compile flags to tell it where to install to?
xamox
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24
votes
4 answers

Estimate Brightness of an image Opencv

I have been trying to obtain the image brightness in Opencv, and so far I have used calcHist and considered the average of the histogram values. However, I feel this is not accurate, as it does not actually determine the brightness of an image. I…
Lakshmi Narayanan
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19
votes
2 answers

Detect rectangular portraits of people on images with OpenCV

I have many images of yearbooks with people portraits and I'm trying to build an algorytm that will detect those portraits. At least, to detect correct rectangular portraits. Example 1 Example 2 I'm trying to investigate three directions: Face…
Max Chernopolsky
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19
votes
4 answers

Retrieving the current frame number in OpenCV

How can I retrieve the current frame number of a video using OpenCV? Does OpenCV have any built-in function for getting the current frame or I have to do it manually?
Ruhi Akaboy
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17
votes
7 answers

local module descriptor class for com.google.android.gms.vision.dynamite not found

I'm new at Google Mobile Vision api and I've been using barcode detector class to detect barcodes. The app works fine but it does not work in my android 4.2.2 phone. I've updated the play services to v10.0.1 but still no good. When connected to…
Nik
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13
votes
5 answers

cv2.rectangle: TypeError: Argument given by name ('thickness') and position (4)

I am trying to visualize bounding boxes on top of an image. My Code: color = (255, 255, 0) thickness = 4 x_min, y_min, x_max, y_max = bbox cv2.rectangle(img, (x_min, y_min), (x_max, y_max), color, thickness=thickness) and I get TypeError: Argument…
Sam Shleifer
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11
votes
1 answer

Implementing Sobel Operator

I am trying to implement a sobel operator in both horizontal and vertical direction. But somehow I am getting the reverse output. The code I have attached below. For the horizontal mask char mask [3][3]= {{-1,-2,-1},{0,0,0},{1,2,1}}; void…
Abhishek
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11
votes
1 answer

Industrial vision camera with Python

Is there any industrial computer vision camera that comes with a Python interface, or that has a well developed third-party solution? I have been doing some work using webcams, which are easily accessible through for example OpenCV. However, now I…
sulkeh
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11
votes
1 answer

Does MATLAB use OpenCv CascadeClassifier?

I have a question about CascadeObjectDetector in MATLAB. In source code of CascadeObjectDetector in MATLAB I see: pCascadeClassifier; % OpenCV pCascadeClassifier Then I see: %------------------------------------------------------------------ %…
EgorD
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10
votes
3 answers

Error: (gcloud.alpha.functions.deploy) ResponseError: status=[403], code=[Forbidden], message=[Cannot access Google Cloud Functions API in project

I'm new using Google's APIs. I'm following step by step the next tutorial made by Google: https://cloud.google.com/functions/docs/tutorials/ocr I want to deploy a specific function provided by Google (the processImage function). I entered this into…
DavidQuezada7
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9
votes
2 answers

OpenCV with stereo 3D reconstruction

Say I plan to use OpenCV for 3D reconstruction using a stereo approach...and I do not have any special stereo camera but only webcams. 1.)How do I build a cheap stereo setup using a set of web cams? 2.)Is it possible to snap two images using web…
seahorse
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9
votes
2 answers

is there a way that Cloud Function can deal with long run operation?

If I want to use GCP Cloud Function to automate (also parallelise) image recognition using VISION API (Python3), but CF has a hard limit of 9 minutes duration. What if a image is very big, and takes a long time be recognised (longer than 9 minutes)?…
FishingSlark
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9
votes
5 answers

Is number recognition on iPhone possible in real-time?

I need to recognise numbers from the camera image on iPhone, in real-time. I know there will be no more than 5 digits on the image. Is this problem realistic to solve given the computational specifications of the iPhone? Does anyone have any…
MitLap
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9
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1 answer

Detect circles width vision framework on ios11?

I need to detect circles in an image. iOS11 allows to detect and track rectangles but how can we track circles ? Is it possible ?
fvisticot
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