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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
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OpenNI Intrinsic and Extrinsic calibration

How would one extract the components of the intrinsic and extrinsic calibration parameters from OpenNI for a device such as the PrimeSense? After some searching I only seem to find how to do it through ROS, but it is not clear how it would be done…
Jack H
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What is the relationship between color space RGB, XYZ and the color matching function?

What is the relationship between color spaces (RGB, XYZ) and the color matching function? Let's say we have some color matching function in the color space XYZ (3 row matrix). We also have the transformation matrix which translates from XYZ…
RebeccaK375
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Python OpenCV pure white background

I have a DIY home photo studio to take photos. I want them to be on pure white background (#FFFFFF) with minimum user interaction This is original picture i have (no any processing, just raw JPG from camera) I implement simple python program with…
striker
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What is the definition of "high-capacity cnn" or "high-capacity architecture"?

I found the phrase "high-capacity cnn" in these two papers: 1.Rich feature hierarchies for accurate object detection and semantic segmentation 2.Region-based Convolutional Networks for Accurate Object Detection and Segmentation I've searched it up…
Shieh Kai Yong
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Keras imageGenerator Exception: output of generator should be a tuple (x, y, sample_weight) or (x, y). Found: None

I'm currently trying to follow the example here using a dataset I generated by myself. The back end is run using Theano. The directory structure is exactly the same: image_sets/ dogs/ dog001.jpg dog002.jpg ... cats/ …
Andros Wong
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Issues with shaping Tensorflow/TFLearn inputs/outputs for images

To learn more about deep learning and computer vision, I'm working on a project to perform lane-detection on roads. I'm using TFLearn as a wrapper around Tensorflow. Background The training inputs are images of roads (each image represented as a…
Janum Trivedi
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How do I minimize global error across multiple image homographies?

I am stitching together multiple images with arbitrary 3D views of a planar surface. I have some estimation of which images overlap and a coarse estimate of each pairwise homography between pairs of overlapping images. However, I need to refine my…
user2446426
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Recognition of an animal in pictures

I am facing a challenging problem. On the courtyard of company I am working is a camera trap which takes a photo of every movement. On some of these pictures there are different kinds of animals (mostly deep gray mice) that cause damages to our…
Lukas Hruby
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How to calculate % score from ORB algorithm?

I am using the ORB algorithm of OpenCV 2.4.9 with Python to compare images. The ORB algorithm does not return the similarity score as a percentage. Is there any way to do this? My code to compare images using ORB is as follows img1 =…
user93
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Dlib frontal face detection for small faces

I am using Dlib's frontal face detector to detect faces in an images; however, it cannot detect faces smaller than 80 by 80 pixels. Dlib's example in face_detection_ex.cpp upsamples the input image using pyramid_up() to increase the face sizes.…
mhaghighat
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What is the order of mean values in Caffe's train.prototxt?

In my Caffe 'train.prototxt' I'm doing some input data transformation, like this: transform_param { mirror: true crop_size: 321 mean_value: 104 # Red ? mean_value: 116 # Blue ? mean_value: 122 # Green ? } Now I want to…
mcExchange
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2D Coordinate to 3D world coordinate

I want to convert 2D Image coordinates to 3D world coordinates. I am using the ZED camera which is a stereo camera and the sdk shipped with it, provides the disparity map. Hence I have depth. The two cameras are parallel to each other. Although this…
Shashwat Verma
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Outermost contour extraction from silhouette

I need to retrieve the outermost contour of several silhouettes, possibly storing the contour coordinates in a clockwise or counterclockwise order. From what I've read, this kind of result can be archived by using OpenCV's Canny + findContours.…
Izzy88
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Distance Transform in OpenCV Python automatically converting CV_8UC3 to CV_32SC1 creating an assertion error

I am trying to apply the WaterShed algorithm to an image as per the tutorial: OpenCv WaterShed Docs . I have earlier applied Otsu's thresholding after Gaussian filtering and Morpholigical Transformations on a greyscale image to improve Image quality…
Anindita Bhowmik
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How to flip only one axis of transformation matrix?

I have a 4x4 transformation matrix. However, after trying out the transformation I noticed that movement and rotation of the Y axis is going the opposite way. The rest is correct. I got this matrix from some other API so probably it is the…
5argon
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