Questions tagged [image-processing]

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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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7 views

Tensorflow Image segmentation [closed]

For my Image colorization project, I am trying to be able to get the class label for a given pixel in an image. For example, I want to be able to know if a given pixel of the image belongs to sky, ...
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1answer
60 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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17 views

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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13 views

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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18 views

Automatically detect Object points and Image points from a Single Grid for Camera Calibration?

What is the best generalised algorithm suited for detecting Object points and image points automatically from a single grid image with different line thickness and luminance intensity? Link defining ...
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1answer
32 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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1answer
50 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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42 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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34 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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26 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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21 views

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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1answer
48 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
34 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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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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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
67 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
170 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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18 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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29 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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43 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
51 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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39 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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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
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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1answer
325 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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50 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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14 views

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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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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8 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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63 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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28 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
233 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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40 views

How to do mathematical morphology manually? Erosion, dilation, open, close

How do you do mathematical morphology manually? If you have a kernel or structuring element B1 do you move the origin of B1 to every pixel in the matrix A1 and see if it is a perfect match, partial ...
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0answers
17 views

impact of the single pixel in disparity

Disparity essentially means the distance of a corresponding pixel in another image ( in pixels). This is clear and understood. When I looked after how the depth is related to disparity, then I found ...
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13 views

Similarity of images with tree shape drawn objects

I'm trying to find the best algorithm for my task. I have images looking like this one: I want to find the most similar ones from a set of such images. I tried several algorithms to compute the ...
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1answer
29 views

Image segmentation generates inclusions and is not smooth

I am performing segmentation using opencv, but the segmented image has regions with breaks and also the border isn't smooth. How can I handle this problems?
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1answer
727 views

How does a predictive coding aid in lossless compression?

I'm working on this lab where we need to apply a lossless predictive coding to an image before compressing it (with Huffman, or some other lossless compression algorithm). From the example seen ...
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1answer
29 views

Given two data feeds, find out if they capture the same information

Say, there are two camera feeds, how can I establish if they were filming the same scene? It seems plausible that there are algorithms that somehow calculate mutual information and detect "causality ...
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2answers
335 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
46 views

what is meant by support of a filter?

what is meant by support of a filter in context of image processing? In the attached link of a short tutorial for detecting bar in an image by gabor filter,it is said that γ=1 helps in finding the ...
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51 views

Why is sparsity useful in dictionary learning?

What is the particular reason for which we use sparse matrix X in dictionary learning equation Y=DX where Y is the signal matrix, D is dictionary and X is the coefficient matrix?
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2answers
42 views

identify abrupt frame changes in a video

The frames of live streams or videos, in general, do not flow smoothly. A sports game would have multiple cameras recording the game and hence, there will be camera switches in the stream. I am ...
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1answer
84 views

what the mean and median filters with an n x n kernel (neighborhood) do to the grey-levels of the image? [closed]

sorry i haven't found a good title for these three questions i'm wondering if someone could give me explaination with proof (if possible ) of these three questions : Given a grey-level image stored ...
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1answer
34 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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0answers
98 views

Transform Image Point to Azimuth and Elevation

I'm working on an object tracker where I need to report the azimuth and elevation of targets. Both values should be scaled from degrees to unsigned 32-bit integers. For now I can ignore lens ...
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0answers
53 views

How to find corresponding points between two photos when there's a repeated pattern?

Suppose that I have two photos, I1 and I2 and I want to find a set of corresponding points between the two photos to define a homography between them. There are many algorithms for this purpose, ...

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