Questions tagged [image-processing]

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2
votes
1answer
357 views

Algorithms to correct misspelled word?

At present, I am doing a project on Optical Character Recognition (OCR). I am looking forward to improve the results by checking the output words of my OCR code with existing words from a text file. ...
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0answers
50 views

How to detect if objects are on top of each other?

Lets say we know the co-ordinates of each object in a camera co-ordinate systems. How do we find out if some object is on top of each other? My idea is: Compare each object and point with one another....
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0answers
65 views

Up to what extent the hypothesis of piece wise constant intensity values is valid in ocean images?

Usually, in MR images one hypothesis research communities are making is, " the spatial intensity distribution is piecewise constant and that each tissue corresponds to a unique grayscale level. Based ...
2
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1answer
68 views

Color Filler Algorithm

Is there an algorithm that fills the area outside the edges? e.g.: From this to this
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0answers
36 views

Gradient Direction Equation: Color Value

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . On computing the gradient direction, given the equation: theta = ...
1
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1answer
293 views

Stroke Width Transform: Gradient Direction Computation

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . Having a simple image with random texts, that underwent gray ...
6
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2answers
47 views

Determining width of paths

I have an image, like the one below that has different paths. I want to be able to detect the thin parts of these paths and highlight them. What is the best way to go about this?
3
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1answer
269 views

Stroke Width Transform: Gradient Direction and Rays

I've been trying to implement this paper from Boris Epshtein, Eyal Ofek, and Yonatan Wexler, the pioneers of Stroke Width Transform . Having a simple image with random texts, that underwent gray ...
2
votes
1answer
59 views

Extracting intersecting objects of the same colour from an image

What is the good way to extract the objects(circles) from image as shown in picture below? respectively create two images one with lines and one with circles from source image. I started with ...
1
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1answer
162 views

Basic queries for Object Detection using deep learning

I have recently started working on the Object detection using deep learning. I have understood the basic steps of object detection are: Input Image -> Object proposals -> Feature Extraction -> ...
3
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1answer
36 views

Any ideas on implementation of a certain image process?

I recently found this music video. While the music is mislabeled, the video part caught my eye. It seems to be transitioning between two images based on shape? I think its a fade-in/fade-out with the ...
1
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1answer
219 views

How does an image classifier select relevant features?

I am trying to understand cascade classifiers for computer vision. I use OpenCV Traincascade for now and successfully trained some cascades. However I am trying to grasp the whole process. One thing ...
1
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1answer
253 views

Coordinates of the center and the radius of the circle on the image

What is the simplest possible way to calculate the coordinates of the center and the radius of the circle on the image (for example BMP and I'm interested in image of the Sun included below)?
3
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1answer
46 views

Simple Recognition Algorithm, How Does It Work?

I am trying to understand how a simple image recognition of an image with dynamic size could work. What I have seen is that parts of the images are taken and evaluated. For example a simple finger ...
0
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1answer
338 views

Blob detection as Constraint satisfaction problem?

In image processing I have a black and white image which is represented by matrix {0,1}, I have to find blob (a region of connected pixels) in it. I'm confused, can this problem be reduced to ...
3
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1answer
593 views

HandyAR finger tip detection and tracking

I am reading this paper Handy AR. As suggested I am adding certain quotes from paper to get basic idea of what is it about : Intro In this paper, we present and evaluate a method to use a user’...
7
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1answer
2k views

Computer vision: object detection with labels that are single coordinates

Are there papers in the literature that address the following object detection task ? The task can be described as follows: Given a set of images, the labels are just coordinates (x,y) that ...
2
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1answer
321 views

How to use PHOG and LPQ features for Emotion Recognition?

I have a database that consists of PHOG and LPQ features for each image. Now, I wish to train an SVM on these features for emotion recognition i.e SVM classifies the images on basis of emotion in the ...
4
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0answers
62 views

Metrics for image/visual complexity in computer vision/graphics?

Could anyone kindly point me to revenant literature in computer vision/graphics that detail on metrics for image/visual complexity and how to regularize that? More specifically, I am trying to design ...
3
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1answer
81 views

Applicability of Machine Learning on Images.

I am trying to use machine learning to detect and locate an object in a greyscale image. I have about 700 images which are 360x360 pixels in size. See below for an example of the object and image: ...
3
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1answer
268 views

Rearrange pixels to maximize visually distinguishable pattern

I have a dataset full of 0s and 1s, and when I visualize it with t-SNE, which does dimensionality reduction. There is clearly some structure in it as shown below. Each color corresponds to a ...
0
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1answer
82 views

Derivative for x-direction for image

I want to ask, consider we want to compute the slope of x-direction of the following step . The slope for it would be $m =\frac{0}{m_2 - m_1} =\frac{0}{5 - 2}$ which is 0. But the derivate for ...
2
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1answer
490 views

Where I can I find Pre Trained CNN Datasets for Facial Emotion Recognition?

I am working on a project that involves recognising emotion from images. There are two parts in the project: One where I will generate features from images using API's and then classify the emotion ...
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0answers
136 views

Image sharpening : Adding prewitt's filter resulted images. Is it correct?

I'm reading that 'Prewitt' filter is high-pass filter, which means that it can sharpening the image (via edge highlight). But I'm not sure to implement the sharpening process (not just edge detection)...
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0answers
82 views

Reduction of flow-shop scheduling to a real-world computing problem

Consider the following well known flow-shop problem: We are given a set of jobs $J=\{J_1,\ldots,J_n\}$ and a set of resources $R=\{R_1,\ldots,R_m\}$. Each job $J_i$ consists of a set of operations $...
1
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1answer
583 views

Circle Hough Transform. Improvement by knowing edge direction

I'm studying Hough Transform. I have fully understood the HT for detecting lines and successfully implemented it. I have more problems with the circle detection HT. Given a circle, if the radius is ...
1
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1answer
179 views

Algorithms to convert 2D videos to 3D ones

Are there published algorithms that can convert 2D videos to 3D ones? If there are few published algorithms for this I am also interested to know how the conversion quality is.
2
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1answer
209 views

Contrast vs. Brightness question

As part of my homework I need to prove (or disprove) that changing the contrast and, then, changing the brightness is (or isn't) the same as changing the brightness and, then, changing the contrast. ...
1
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1answer
108 views

Is there any good way to judge whether the rectangle is inside the point cloud? [closed]

How to judge whether a rectangle in the figure is inside the given point cloud? For example, in this figure, the red rectangle is outside the point cloud and the green rectangle is outside the point ...
2
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1answer
3k views

What are the pros and cons of RANSAC versus Hough Transform?

A friend needs to find the pool balls in an image of a pool table. Would a Hough transform be a good idea? Why/why not? Would RANSAC be better? The question comes from this study guide (http://www.cc....
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3answers
86 views

Slicing clusters of non-black pixels from an image into separate images

The backstory I have spectrograms of certain repeating sounds. The background of the spectrograms are black and could easily be made transparent if that would help. The sounds are easily distinct ...
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1answer
53 views

Register images from a camera which has undergone pure forward translation

Images are taken by a DSLR camera, always set at a particular Focal length. The scene contains objects with varying distance to the cameras. Since the camera has undergone translation, homography no ...
2
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1answer
674 views

Dynamically Learning Haar Cascade (in OpenCV)

I am new to computer vision so please excuse me if this question is very simple. I am trying to learn how to use the Haar Cascade creation tool provided with OpenCV to train a cascade classifier. It ...
1
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1answer
185 views

How are the number of bytes less than the number of pixels in an image?

Lets take, for example this jpeg image here The image there is 400 x 300, or 120000 pixels and The file size of the image (on my computer) is shown to be 65171 bytes. This means the computer stores ...
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1answer
28 views

What is the need of re-sampling the image for HOG features?

I read Dalal and Triggs paper for HOG description and a blog Chris McCormick HOG regarding the same. The blog says that the image needs to be re-sampled at different scales to recognize different ...
0
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1answer
529 views

Width of a String/Line in an Image

I have been looking for a method to find the width of a line. I found the solution(link: http://www.mathworks.com/matlabcentral/answers/88645-average-width-of-lines), "sum up the image to get the ...
1
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2answers
141 views

Is there a way to tell a picture has been resized?

I need to evaluate if the picture was resized (upscaled). Are there any approaches to that already? If not, what do you recommend me to start with?
3
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1answer
1k views

Removing common background in image processing phase for classification

I'm trying to build a machine learning classifier that can detect which object is in an image. I have a labled training set of images and am currently in the image processing phase. Each of these ...
1
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1answer
47 views

Computing gaussian kernel for image blurring

When I compute a gaussian kernel for image blurring should I normalize the 1D vectors? Because when I apply the raw values sometimes the image gets lighter or darker. The function I'm using is $f(x) = ...
0
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0answers
36 views

How do Perwitt and Sobel detect edges?

I read up on the Perwitt operator and it detects two types of edges (vertical and horizontal). The Sobel operator on the other hand does the same as the Perwitt except that the masks are not constant ...
4
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4answers
3k views

How to generate stereo image pair from a stationary mono camera?

I have a stationary mono camera which captures a single image frame at some fps. Assume the camera is not allowed to move,how do i generate a stereo image pair of the acquired frame? Is there any ...
5
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1answer
846 views

How to calculate Huffman code length without generating the actual huffman code?

Given a vector of elements, how can I calculate the length of the Huffman codewords without generating the Huffman code itself? Using Matlab, I was able to compute the Huffman code and and get the ...
0
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1answer
117 views

Does the SIFT feature be calculated in the original image or the corresponding octave(s)?

Given there are 4 octaves(the 1st octave is the original image, the 2nd octave is half size of the original image, and so on.), does SIFT calculate the keypoint's orientation in the original image or ...
5
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1answer
380 views

Reconstructing a screen of permuted pixels

Reconstructing a screen of permuted pixels Summary Given a video with the pixel locations randomly permuted (once, for the entire video), can we (efficiently) reconstruct the original picture? Let: ...
2
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1answer
181 views

High Dimensional Spaces for Images

Can anyone explain why pictures are not considered 2D, but rather high dimensional? Especially with regards to CV and AI.
4
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1answer
472 views

Efficient flood filling (seed filling)

I am referring to the algorithm that fills a white area of arbitrary shape in a binary digital image, starting from a given white pixel, using the Moore (8 neighbors) or Neumann (4 neighbors) ...
2
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1answer
783 views

Compare phase and magnitude spectrum results of 2 Images

I have read that from Fourier transform we obtain magnitude and phase spectrum. The magnitude spectrum tells you how strong are the harmonics in a image and the phase spectrum tells where this ...
3
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1answer
58 views

Does JPEG compression use a heuristic model similar to MP3?

I know that MP3 uses a compression heuristic that allows it to exclude storing frequency data outside a certain range due to the limits of human hearing. Does JPEG employ some sort of non-linear ...
12
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2answers
3k views

Why is the laplace transform not popular for image processing convolution?

Why is the laplace transform not popular for image processing convolution? Most textbooks only conver the Fourier transforms.
4
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1answer
193 views

perspective transformation of a grid

A perspective transformation of a point is defined as follows: $ x' = \frac{M_{11}x + M_{12}y +M_{13}}{M_{31}x + M_{32}y +M_{33}} $ $ y' = \frac{M_{21}x + M_{22}y +M_{23}}{M_{31}x + M_{32}y +M_{33}} ...