Questions tagged [image-processing]

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How are epipolar lines useful in computer vision?

Why do use epipolar lines and what are it's benefits in computer vision ?I am unable to find the uses of epiploar lines and how they are helpful although i am aware of epiploar geometry concepts. I ...
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10 views

Why are screen recordings on MacOS unable to be played once copy/pasted to a usb drive? [migrated]

If I take a screen recording in MacOS, (seemingly regardless of file size) and copy/paste it into a usb drive, then try to play the .mov file from the usb (on a Mac)I get the error: ...
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1answer
11 views

Performing semantic segmentation on images on word documents

At the moment, I'm making a comparative analysis between two different neural networks for a class. The problem they are both trying to solve is detecting tables on documents. Below is an example of ...
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1answer
84 views

Applying SVD compression to integral point images

Suppose that we have an $m\times n$ matrix $A$ of rank $n$, whose entries are 8-bit unsigned integers obtained from a grayscale image. Now we want to apply SVD to $A$ and to use the first $k$ singular ...
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confusion regarding mid level image processing task?

I am reading gonzalez chapter1 As shown highlighted in attached snapshot, what is meant by this mid level task: description of those objects to reduce them to a form suitable for computer processing, ...
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1answer
272 views

Why is Scale Space Needed to Detect Scale Invariant Features?

I have been doing research on the SIFT (scale invariant feature transform) algorithm, and while I have repeatedly read that in order to detect image features that do not vary with respect to scales of ...
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1answer
61 views

Comparing variable image to static image

What are Levenshtein distance algorithms, but for images? I will have one static image (the target: what it should look like) and one variable image (actual: what the user has created) For example, ...
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1answer
45 views

Sources on dictionary learning and related algorithms

In the context of signal processing and sparse representation of signals, there is a topic called dictionary learning which is basically about how to's of the selection of basis functions used for ...
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1answer
38 views

How do we fix area of detectors in object detection?

I have gone through various articles on medium and also some from other sites trying to understand SSD. I am able to figure out most of the things from articles except this one. They always say that ...
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21 views

I don't understand formula meaning of computer vision Paper

I am master degree student at Computer Science Department. I started master degree at this year. Now I'm reading two papers about computer vision. Actually before time I didn't have experience about ...
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1answer
67 views

What is an algorithm to find the largest rectangle of white space in an image?

Take an image, (the Google home page) is a good example. I want an algorithm to find the largest white rectangle in this image. That is to say, the largest rectangle that would fit in an area of ...
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10k views

What is the difference between the fundamental matrix and the essential matrix?

Could someone, in plain english, explain the distinction between the fundamental matrix and the essential matrix in multi-view computer vision? How are they different, and how can each be used in ...
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What is the best algorithm for detecting the texture of a person's clothes in real-time for a mobile robot?

I am working on the human following robot. the robot extracts a feature of clothes's texture and distinguishes between the people that they stand up in front of the robot. So, the robot needs that it ...
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1answer
40 views

How to jump directly from level 0 to level 5 in a Gaussian pyramid without having the levels 1, 2, 3, and 4?

I am current studying the Laplacian Pyramid as a compact image code by Peter J Burt and Edawrd Hudson. I understood all the concepts but I am having trouble with the equivalent weighting function. I ...
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1answer
57 views

An algorithm to find the closest match between 2 arrays of RGB pixel tuples

So I'm looking for a bit of an abstract algorithm and I'd appreciate any references to read up on. This is a bit tough to explain but I'll try my best. Suppose we have 2 arrays of ...
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How to do 3D Reconstruction with Photogrammetry?

I recently started experimenting with Photogrammetry and I was wondering what it would take to create a own 3d reconstruction software? The goal would be to take a set of input images of a real world ...
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1answer
34 views

Greyscale image to binary image conversion using operations on pixel

Previously, I tried convert a color image into a greyscale image by using pixel values of an image from a simple formula :- Grey = 0.3*Red + 0.58*Green + 0.11*Blue ...
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43 views

Segmenting a cat's side profile and plotting a line on the edges

My goal is to segment the side profile of a cats head and plot a line on the edges of the cat's face, The cats will have different backgrounds, colour and quality, and the feature (cat's face edges) ...
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35 views

Image/Video deblurring

I am currently working on an algorithm that will help to improve shaken blurry images. I know there are plenty of them, such as deconvolution, that is pretty useful though I don't really know how to "...
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29 views

Why HOG angular bins have values between 0 and 180 degrees?

I have learned that HOG angular bins have values from 0 to 180 since the algorithm uses unsigned gradients. I am failing to understand why. As far as I know gradient orientation is calculated as <...
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Image classification with zero data

Given an image of a biology diagram, I would like to classify the diagram into these 4 categories: Plant Animal Cell Anatomy However, I don't have any training data. I would like to avoid the ...
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2answers
401 views

Image convolution - image darkens

I'm using kernel convolution in python to blur an image, but in addition to blurring it also turns the image darker. Could someone explain why it happens? ...
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1answer
61 views

Image segmentation of a high resolution 2D binary image into clusters, threads and points

I use python3 script to find out the area proportion of pixel clusters, threads and points in my image. They are originally 8-bit greyscale TIFF images with a resolution of 2048x2168 pixels. I have ...
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1answer
13 views

“higher intensity” and “high signal intensity” in images

I'm newbie in Computer Vision and image processing. I'm reading the article "Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR" and it said: 2.2.4. WMH ...
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1answer
36 views

Gaussian noise: Image Processing

As we all know, Gaussian Noise follows Gaussian or Normal distribution, and that distribution follows a $BELL$ $CURVE$. As we can see that most of the values are centered around the mean. Now ...
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15 views

Does white balance correction improve the performance of visual object detection?

Visual object detecion aims to locate and recognize objects of interest in images. I wonder, does white balance correction contribute to better performance of visual object detection? Are there any ...
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1answer
120 views

What is f(x,y) in Digital Image Processing?

I am a novice in Digital Image Processing, and while reading the book of DIP by Gonzalez and Woods, I find that they have represented digital image as $f(x,y)$ but nowhere it is mentioned what is $x$ ...
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8 views

Sparse tiling of image

I have a large image which I tile sparsely with small 32x32 tiles - the entire image is not covered. What is an efficient way of storing these tiles so that, given an arbitrary sub-rectangle in the ...
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1answer
220 views

Hausdorff distance between two binary images according to distance maps

I want to compute the Hausdorff distance between two (very large) binary images X and Y, which is: $$H(X,Y) = \max\left\{\,h(X,Y), h(Y,X)\right\}\!$$ with $$h(X,Y) = \sup_{x \in X} \inf_{y \in Y} d(...
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34 views

Tapered Quantization

In Gonzalez et al it is mentioned that Tapered Quantization is I am unable to figure this thing out. I have searched the whole internet, but nothing of the same appears. I need a help in ...
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2answers
1k views

How to count near circular objects in image

I have a image similar to below. In that I need to find all red circles and count them. So, I am thinking to use MATLAB R2011a with Image Processing Toolkit for it. How could I possibly extract them?
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1answer
38 views

How are image processing and computer vision related to artificial intelligence.?

We have often heard both terms image processing and computer vision in AI sessions But i am confused, how they both are related to artificial intelligence?
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30 views

Partial derivatives of bilinear Sampling

I'm going over the paper Spatial Transformer Networks (link). On section 3.3 they introduce bilinear sampling kernel (Eq. 5) $$ V_{i}^{c}=\sum_{n}^{H} \sum_{m}^{W} U_{n m}^{c} \max \left(0,1-\left|x_{...
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23 views

How can i compare lossy image compression techniques?

I need to find which lossy image compression technique is the best. I chose to test JPEG, WebP and BPG. Which criteria can I choose for comparison apart from quality and speed of compression and how ...
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9 views

Deep Learning Technique for Image to Video Conversion

I'm trying to build an engine for the following task: I have n videos, from which I've taken 1 snapshot each. I am trying to train a classification algorithm on these n snapshots. Till now I have ...
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48 views

Image quantization for grayscale images with alpha channel

I am looking for algorithm that quantize grayscale image that contains alpha to 4-bits (16 colors). I quite like the effect that is used in IrfanView to decrease color depth, however, I dont know the ...
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1answer
55 views

Fitting a polynomial to a set of points or to a skeleton

Available data Available to me is a set of points which can be represented as shown in image 1: Also available to me is a non-continuous path derived from this data. It is not important how this non-...
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40 views

Do image artefacts reveal the original image orientation?

An image is taken and then rotated by an arbitrary angle and cropped. Let us assume that the original image is rather meaningless and is not aligned in any way. Given the rotated image, is it ...
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1answer
82 views

What are some research papers or techniques that deals with fitting clothes on a human?

Given an image of a dress (from different angles), what could be ways to fit it on a human image (again multiple angles corresponding to dress)? Any link to research papers or tutorial regarding this?
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191 views

Compare vectors, photo mosaic

I’m trying to make a photo mosaic web application. I split the main picture in to a number of squares. I split this square up in to 9 squares. Then I calculate the mean color (RGB) of the entire ...
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13 views

Calculating spatial “orderedness” at each position in a binary image: entropy? lacunarity?

Let's say I have image where all pixel values are either 0 or 1. What I'd like to do is to be able to generate a new image with the same dimensions where each pixel represents how "ordered" the area ...
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1answer
406 views

Minimum Bounding Quadrilateral

In an image processing project (using opencv with python), I am trying to detect as precisely as possible the location of a rectangular object in a photograph. My final goal is to output the 4 corners ...
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54 views

Modifying the JPEG compression to use custom block patterns

recently, while watching a video about machine learning, I had an idea about creating an image compression algorithm, that works similar to JPEG, but is based on arbitrary bitmaps as blocks. I should ...
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1answer
3k views

What is the difference between luma and luminance?

I understand the following (correct me if I'm wrong): Statements Luma as the weighted sum of RGB gamma corrected components, but luminance is the weighted sum of RGB linear components. The gamma ...
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Does the illumination color (red/blue/green) has any effect over the disparity map generated from a stereo image?

I have a working model that creates a disparity map using stereoscopic image processing using opencv. I am thinking of improving the disparity map by using illumination and stuck with different ...
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10 views

Constructing a 3D virtual map from 2D Depth Maps and $x, y, z, \theta$ coordinates

Context: I intend on building a quadrotor which can generate a 3D virtual map of an area of which it captures photos with a 2D camera. I plan on first training a Convulational NN to return a depth ...
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82 views

Training of two 3x3 convolution layers vs training one 5x5 convolution layer

I'm not 100% sure this is the right stackexchange, please feel free to redirect me to another one. I know that two 3x3 convolution layers can be equivalent to one 5x5 convolution layer. I also know ...
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29 views

Correct way to downsample a high-res image with jitter?

I'm new to image processing and I'm trying learn about image AA and upsampling algorithms such as those used in game engines. Engines tend to use jitter in order to get multiple samples from the same ...
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1answer
234 views

Efficient Algorithms for Destroyed Document Reconstruction

I am not certain this is the proper site for this question however I am mainly looking for resources on this topic (perhaps code). I was watching TV and one of the characters had a lawyer who ...
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41k views

What are the differences between computer vision and image processing?

What are the differences between computer vision and image processing? For example, in object recognition, what are the roles of computer vision and image processing?

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