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Questions tagged [image-processing]

In general, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame.

12
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2answers
5k views

Bitmap alpha bevel algorithm?

I am looking to create an algorithm which adds a bevel effect to a bitmap using it's alpha as a bump map. How would I go doing something like this? I have tried specular lighting but I only get the ...
8
votes
2answers
4k views

How to implement a gradient based Hough transform

I am trying to use the Hough transform for edge detection, and would like to use gradient images as the basis. What I have done so far, given the image I of size <...
44
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5answers
8k views

Point Pattern Recognition

Having two different size of sets of points (2D for simplicity) dispersed within two different size squares the question are that: 1- how to find any occurrence of the the small one through the ...
4
votes
3answers
2k views

Bitmap border/stroke alogirthm?

I am looking for an algorithm that adds borders to a bitmap image(very much like the photoshop stroke effect) but one that will also have antialiasing to the borders(or one that copies alpha from the ...
52
votes
8answers
7k views

What are some good signal and image processing blogs worth following?

Are there some good sites or blogs where I can keep myself updated on the latest news and papers about image and signal processing research, or I should just check out "classical" providers like IEEE ...
32
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2answers
14k views

What's the difference between the Hough and Radon transforms?

I'm familiar with the Radon transform from learning about CT scans, but not the Hough transform. Wikipedia says The (r,θ) plane is sometimes referred to as Hough space for the set of straight ...
6
votes
1answer
496 views

find a line go through the center mass and that line must be inside object area

I have an object (orange color object) and I know its centroid/center mass C. I want program to automatically find another point ( can be point 1, point 2, point 3 or point 4 and so on) such that the ...
29
votes
5answers
2k views

Detecting Trail in Forest Images

Is anyone aware of any research/papers/software for identifying a trail (as a line or point-to-point curve) in an image of a forest scene (from the perspective of the camera standing somewhere along ...
16
votes
1answer
2k views

Removing Glare from Image

Disclaimer: I am in NO way engaged in signal processing. Just very curious... Ny question is, very simply: is it possible to apply software processing to an image to remove or reduce headlight glare?...
1
vote
3answers
530 views

Skip corrupt part of jpeg

Is it possible to read a JPEG file and skip parts that are corrupt? I have three corrupt JPEG files and I can detect the first corrupt block, but can I skip it and continue with the next block? I ...
13
votes
4answers
9k views

How to detect corners in a binary images with OpenGL?

I have binary 160x120 images such as: I would like to detect corners of those white blobs. They are previously closed by mathematical morphology so there shouldn't have any inner corners. In this ...
13
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2answers
5k views

Why is the difference of gaussians scale space scale invariant?

I'll use the Scale-invariant feature transform algorithm as an example here. SIFT creates a scale space based on scaled gaussian filtering of an image, and then computes the difference of gaussians ...
5
votes
2answers
113 views

How to statistically quantify the coverage of features in the data?

I have an image. I find features on it using different methods. I want to quantify that which method performs the best. The creteria is how many features per unit area of the image are and how they ...
173
votes
5answers
61k views

“River” detection in text

Over on the TeX stackexchange, we have been discussing how to detect "rivers" in paragraphs in this question. In this context, rivers are bands of white space that result from accidental alignment ...
8
votes
2answers
2k views

YV12 to RGB - What is wrong with my algorithm?

I am attempting to convert YV12 to RGB using the following fragment shader: ...
10
votes
1answer
154 views

Data decomposition method invariant to small shift and scale?

Is there a data decomposition method similar to eigenvalue that estimates projection matrix to reduce dimensionality but does not project similar vectors too far away in euclidian distance terms from ...
39
votes
6answers
5k views

What Properties Make Certain Wavelets “Better” Than Others In Image Compression?

I am trying to teach myself more about image compression using the wavelet transform method. My question is: What is it about certain wavelets that make them preferable when compressing images? Are ...
2
votes
2answers
190 views

Is there an algorithm to compare several pictures?

I'm looking for an algorithm to store small dimensions of some pictures and later search on the stored data for matches similar to a new picture. Maybe something with Self Organizing Map in machine ...
6
votes
1answer
857 views

How does google map put together satellite pictures?

Just out of curiousity, does anyone know how does google map put together all those massive quantity of satellite pictures with with high accuracy? What advanced computer science technology has it ...
16
votes
2answers
15k views

Wiener Filter for Image Noise Reduction (Image Denoising)

I'm trying to get my head round the operation of the Wiener filter for the purpose of image noise reduction. In my case I'll have used another noise reduction filter first and will then use the result ...
2
votes
1answer
74 views

Given some parameters, how do you determine how much of an image sensor an object will consume? [closed]

If I have the details of a scene and a camera, how can I tell how much of my camera's image sensor will be taken by a certain object in space? For example, if I have a painting that is 1m by 1m, it ...
15
votes
2answers
16k views

Downsampling an image by an integer factor

When downsampling an image by an integer factor $n$, the obvious method is to set the pixels of the output image to the average of the corresponding $n \times n$ blocks in the input image. I remember ...
20
votes
3answers
9k views

Fastest Algorithm for Distance Transform

I am looking for the fastest available algorithm for distance transform. According to this site http://homepages.inf.ed.ac.uk/rbf/HIPR2/distance.htm, it describes: The distance transform can be ...
6
votes
1answer
1k views

Skel to infinity morphological operations on 3D volume

I have a 3D volume image that consists of 2D tomographic images. In MatLab, for 2D images, we can use bwmorph and call for 'skel' operation to infinity to get a pixel thick overall outline of the ...
10
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3answers
456 views

Image analysis - fiber recognition

I am completely new to image analysis. Do you know how to binarize this image in such a way to get the fibers only? A step by step procedure would be awesome, but any hint is appreciated as well. I ...
14
votes
1answer
5k views

What distance metric can I use for comparing images?

I usually use the mean squared error (MSE) or peak signal-to-noise ratio (PSNR) to compare two images, but this isn't good enough. I need to find a formula that returns a very big distance between an ...
22
votes
3answers
12k views

How do I remove motion blur?

Is there a generically accepted method of removing motion blur from an image. For a simple case, we can assume that motion happens in a straight line. I assume that it's a two part process composed of ...
24
votes
3answers
2k views

How can I reconstruct a 3D structure from a set of images?

I have a set of contours (set of line segments) grouped in the following way: $S_i = \{I^0, I^\frac{\pi}{4}, I^\frac{2\pi}{4}, \ldots, I^\frac{7\pi}{4} \}$ where $S_i$ denote sequence of photos of ...
16
votes
2answers
819 views

How do you measure “detail” of a signal?

I have an image and I would like to measure the amount of detail in it. Another way to look at it is to measure how blurry an image is. One way is to analyse the high frequency components in the ...
31
votes
5answers
3k views

What Factors Should I Consider in Choosing an Edge Detection Algorithm?

I've learned about a number of edge detection algorithms, including algorithms like Sobel, Laplacian, and Canny methods. It seems to me the most popular edge detector is a Canny edge detector, but is ...
15
votes
2answers
2k views

How can I lowpass filter by only reducing peak data?

I have a 2D image, which I want to lowpass filter, with these constraints / quality metrics: I can not "add" light to the image, so each pixel in the result should be <= the corresponding pixel in ...
7
votes
2answers
869 views

How to apply a filter kernel

A filter that can be used for digital signals like audio, video or image processing can be defined using a matrix ("kernel") that weights the surrounding area (this is a description I read in lecture ...
13
votes
3answers
5k views

Image Processing: How to detect a quadrialteral signboard in image?

How can I detect a quadrilateral signboard from an image captured using a mobile phone? How can i detect shapes like rectangle? rounded rectangle (rounded corners instead of shape corners)? I am ...