Signal Processing Stack Exchange
Signal Processing Stack Exchange

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.

Most image-processing techniques involve treating the image as a two-dimensional signal and applying standard signal-processing techniques to it. The output of image processing may be either an image or, a set of characteristics or parameters related to the image. Image processing usually refers to digital image processing, but optical and analog image processing also are possible.

Source: Wikipedia

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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 Transactions, Elsevier, etc?
martjno
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Why are Gaussian filters used as low pass filters in image processing?

In 1d signal processing, many types of low pass filters are used. Gaussian filters are almost never used, though. Why are they so popular in image processing applications? Are these filters a result of optimizing any criterion or are just ad hoc…
nimrodm
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What are the practically relevant differences between various image resampling methods?

Mathematica's ImageResize function supports many resampling methods. Not being familiar with this area, beyond nearest neighbour, bilinear, biquadratic and bicubic (which are obvious from the name), I am lost. Can you point me to some source that…
Szabolcs
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Difference between SNR and PSNR

I understood that SNR is the ratio of signal power to the noise power. In terms of images, how the original image is affected by the added noise. In PSNR, we take the square of the peak value in the image (in case of an 8 bit image, the peak value…
Premnath D
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How can I remove shadows from an image?

I have this image I would like to remove the shadow from the image. I know a lot of different methods like certain morphological operations have been used to remove shadows: I have created this mask for the same image Are there some other methods…
vini
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How do I recover the signal from an ECG image

In my project, I have to digitize an ECG image taken with a normal camera (jpeg). For example, I have the following camera captured image: and I want to get something like this:- and then the digitized data (x,y points), like in this video on…
Deepak
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Measuring length of DNA fibers from an image of single molecules

I am a biologist with very little experience with image processing but have sufficient knowledge of MATLAB and have the image processing toolbox. Ideally I am looking for a MATLAB based solution, but an approach outlining how to go about it would…
Lee Sande
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How to detect edges and rectangles

I try to detect rectangles in images. The background of the images is one color (most of the time). I tried two methods to get an binary image (1 = background, 0 = edges), to do an Hough Transformation later on... Sobel or Canny Filter Smooth image…
patr
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How to match a drawn Chinese character to a database of stroke animations

I have a database of Chinese character stroke animations. Each entry is basically a set of points which shows how and in which order a character should be drawn. To make lookup easier, I would like to allow the user to manually draw a character with…
laurent
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monochrome (1-bit black-and-white) image conversion

When converting scanned text to a 1-bit black-and-white image what are some filters that one can apply in the process to improve the result? Right now I am running into the problem where dithering errors make the image look horrible. Update: I…
m33lky
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Auto-focus estimation?

What kind of analysis might be used on sets of 2D monochrome image matrices or bitmaps to estimate or compare their relative quality of being "in focus"? Is there an efficient way of computing a scalar metric on something like overall contrast,…
hotpaw2
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Wavelet Transform

I want to perform 2D haar discrete wavelet transform and inverse DWT on an image.Will you please explain 2D haar discrete wavelet transform and inverse DWT in a simple language and an algorithm using which I can write the code for 2D haar dwt?The…
user1320483
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How does auto focus in cameras work?

I am just wondering how does camera auto focus work. What kind of processing does it do on images in order to adjust the focus? Is there freely available code that detects the focus level of an image or video?
Cory
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Chroma-Subsampling: How to properly calculate the data-rate

I am having a hard time understanding how to calculate the data rate when leveraging chroma-subsampling in e.g. a Y'UV image: I have the following examples for a calculation: Image resolution: 352*288 Frequency: 25 fps For (4:4:4) the example…
jottr
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Image Processing - Counting nuclei

I am trying to create a program that can count the number of nuclei in such an image: What I've already done is the following, step by step: Apply an Alternating Sequential Filter (closing and opening the image with gradually bigger structuring…
Thiago
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