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Questions tagged [computer-vision]

Use this tag for questions related to Computer Vision -- any aspect of software that enables computers to perceive, understand and react to their environment using cameras. For questions related to image filtering and quantification, use the tag [image-processing] instead.

Computer vision enables images, or sequences of images, to be processed by a computer using algorithms. There are many aspects to computer vision, including mathematics, physics (especially optics), imaging hardware, , and .

Some basic techniques used in computer vision are:

  • Image acquisition
  • Pre-processing
  • Feature Extraction
  • Detection/Segmentation
  • High-Level processing
  • Decision making
13127 questions
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Image comparison algorithm

I'm trying to compare images to each other to find out whether they are different. First I tried to make a Pearson correleation of the RGB values, which works also quite good unless the pictures are a litte bit shifted. So if a have a 100% identical…
honeymoon
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What is the difference between a disparity map and a disparity image in stereo matching?

I am new to stereo matching. I couldn't understand the concept of disparity. What are a disparity map and disparity image, and what is the difference between them?
user2522560
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Sobel filter kernel of large size

I am using a sobel filter of size 3x3 to calculate the image derivative. Looking at some articles on the internet, it seems that kernels for sobel filter for size 5x5 and 7x7 are also common, but I am not able to find their kernel values. Could…
Aarkan
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module' object has no attribute 'drawMatches' opencv python

I am just doing an example of feature detection in OpenCV. This example is shown below. It is giving me the following error module' object has no attribute 'drawMatches' I have checked the OpenCV Docs and am not sure why I'm getting this error. …
Javed
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How to calculate the number of parameters of convolutional neural networks?

I can't give the correct number of parameters of AlexNet or VGG Net. For example, to calculate the number of parameters of a conv3-256 layer of VGG Net, the answer is 0.59M = (3*3)*(256*256), that is (kernel size) * (product of both number of…
Eric
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How to begin with augmented reality?

I'm currently an undergrad in computer science and I'll be entering my final year next year. Augmented reality is something I find to be a really interesting topic, but I have no idea where to start learning about it. Where do you start learning…
Terri
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What is the gradient orientation and gradient magnitude?

I am currently studying a module in computer vision called edge detection. I am trying to understand the meaning of gradient orientation and gradient magnitude.
Jack welch
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connected components in OpenCV

I am looking for an OpenCV function that can find connected components and perform a few tasks on them ( like getting the number of pixels, contour, list of pixels in the object etc.. ) Is there a function of OpenCV (C++) that is similar to MatLab's…
EyalG
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Detect and visualize differences between two images with OpenCV Python

I have two images and would like to make it obvious where the differences are. I want to add color to the two images such that a user can clearly spot all the differences within a second or two. For example, here are two images with a few…
PlsWork
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CNN - Image Resizing VS Padding (keeping aspect ratio or not?)

While usually people tend to simply resize any image into a square while training a CNN (for example resnet takes a 224x224 square image), that looks ugly to me, especially when the aspect ratio is not around 1. (In fact that might change ground…
Yoni Keren
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Deep Belief Networks vs Convolutional Neural Networks

I am new to the field of neural networks and I would like to know the difference between Deep Belief Networks and Convolutional Networks. Also, is there a Deep Convolutional Network which is the combination of Deep Belief and Convolutional Neural…
user3705926
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What algorithm could be used to identify if images are the "same" or similar, regardless of size?

TinEye, the "reverse image search engine", allows you to upload/link to an image and it is able to search through the billion images it has crawled and it will return links to images it has found that are the same image. However, it isn't a naive…
mmcdole
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Detect text area in an image using python and opencv

I want to detect the text area of images using python 2.7 and opencv 2.4.9 and draw a rectangle area around it. Like shown in the example image below. I am new to image processing so any idea how to do this will be appreciated.
User9412
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How do I increase the contrast of an image in Python OpenCV

I am new to Python OpenCV. I have read some documents and answers here but I am unable to figure out what the following code means: if (self.array_alpha is None): self.array_alpha = np.array([1.25]) self.array_beta = np.array([-100.0]) #…
tsaebeht
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how to add border around an image in opencv python

If I have an image like below, how can I add border all around the image such that the overall height and width of the final image increases but the height and width of the original image stays as-is in the middle.
Anthony
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