This tag covers signal processing where input is an image, such as a photograph or video frame and the output could be an improved or altered image, parameters related to the image or information about features within the image.

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19 views

Fit a plane on a 2d picture

My supervisor gave me the hint, to fit a plane on a 2 dimensional image and substract it from it before doing the fast fourier transformation to reduce low frequencies. I get the low frequencies ...
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1answer
38 views

How to calculate the luminance of an image?

Is there any method for calculating luminance of an image? As from wiki got to know Luminance is an amount of energy perceived by the observer and LUX is different from brightness. But still is ...
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16 views

Coherence of specific area of an image

I have to detect an object in an image. The manner that I am using gives me a number of possible areas of the image that may contain the object. I want to check which is the most coherence area of ...
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5 views

Image format for partial rendering [closed]

I'm developing an artist portfolio website and displaying a lot of paintings on it organized by collections. To speed up loading time, I'm looking for a progressive image compression format that would ...
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1answer
39 views

How to find out whether guassian or salt& pepper noise present in an image, Is there any algorithm

Is there any algorithm for identifying the noise in an image I have to identify whether the noise present in a mammogram image is guassian or salt& pepper.
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1answer
24 views

How matching pusuit algorithm works

I could infer from books and wiki that a matching pursuit finds signal approximations from a redundant dictionary. Let f be the signal, ai be the basis and Ri be the residue.. here we choose the inner ...
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1answer
18 views

Dark image separation

So I have an image. I take it into HSV format and v has its intensity values. now the intensity values of v vary from ...
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1answer
78 views

What is the type of noise in this image?

what reason could make the noise/effect in this image? Below is the original Thanks!
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1answer
42 views

Can a digital image be considered as a tensor ? or have a tensor like structure?

I am wondering if one can assume that a digital image has a tensor structure. I mean for example when we talk about isotropy in image processing, we are talking about the intensity arranged in a ...
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2answers
78 views

Transformation of coordinate set

I have a problem in which i have a video that was taken from the side of the subject, something like this and i need to transform the coordinates of the subject to be as if the photo was taken from ...
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1answer
32 views

Fast Fourier Transformation using parallel processing coding for image processing [closed]

I'm now working in parallel precessing -and i want a full code for fast Fourier transform(FFT) written parallel processing Code for any image processing application
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1answer
29 views

Medical Image quality assessment

How to objectively assess the quality of a medical image(CT,PET,MRI)? What factors should be considered?
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1answer
40 views

homography matrix problem

i have mini project to do about homography , but i am really a beginner in matlab . i have calculated the homography matrix easily by taking a set pixels from both images but the problem is how to ...
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1answer
35 views

Upscaling detection approach

I'm trying to implement a solution that would, to some extent, evaluate a picture telling what are the chances that it was upscaled from the smaller image. My approach is as follows: Take a picture ...
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1answer
46 views

What preprocessing technique can help me to filter the background text noises using matlab…the image is shown below?

Can anyone help me to improve the degradation of the following image....i am working on OCR system in Amharic language and what is the best image filtering technique that can help me to separate ...
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0answers
17 views

How to programatically perform image segmentation in real-time

I am currently trying to segment ultrasound images of blood vessels (video frames), such as the one directly below. Using a simple binary filter on the saturation channel (code below), I can get a ...
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2answers
100 views

How to apply a 2D -2D homography matrix on an image?

i have mini project to do about homography , but i am really a beginner in matlab . i have calculated the homography matrix easily by taking a set pixels from both images but the problem is how to ...
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0answers
10 views

Need to order a set of colors to build a feature vector

I am working on Computer Vision task of object classification with python and OpenCV. Currently I am extracting some characteristic colors of an image using K-means clustering on all the pixel to ...
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2answers
56 views

imshow command for Gaussian function

I'm trying to plot 2D gaussian function using "imshow" in MATLAB. However I could not see any white points in image. I tried to change sampling values and limits of x and y values. In addition to ...
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0answers
19 views

Equivalent of the Shepp-Logan phantom for video denoising

The Shepp-Logan phantom is a standard test image used in reconstruction algorithms as well as image denoising. Does an equivalent image sequence exist for testing video denoising algorithms? I know ...
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0answers
30 views

How to compute Gradient of an image with kernel in python

Using python numpy or scipy I am trying to perform cross-correlation on each pixel of an image using a 3 dimensional kernel. I am more interested in looping into each pixel and applying the kernel ...
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18 views

What are most often used and effective algorithm to compensate the imaging depth

I hope the picture below says everything: Assume the center of camera lens is aligned with the centroid of target. The left picture shows the ideal positioning, i.e., the target is placed at the ...
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0answers
24 views

DICOM codec for Windows Media Player

I have been searching online for a DICOM codec which allows me to play DICOMs in Windows Media Player. I found Dicom Media Bridge which is not free. Could someone let me know if there is a codec for ...
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0answers
25 views

Creating a texture image from existing image

I have some unusual question. I have searched online and couldn't find something similar to what I want to achieve. I have an image, and I want to create a new image from it (in the same size), so ...
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3answers
25 views

Histogram Equalization - mapping a certain portion of pixels to pure black and white

How can I make sure to map, for example, 7% of the pixels to pure black (0) and pure white (255) in a grayscale image?
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1answer
44 views

Given an image how should I detect this is a day picture or night picture?

I have a 2D image which contains R G and B values. I think this should be purely based on averaging of pixels and selecting the threshold to decided whether this is day picture or night one. Can you ...
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1answer
29 views

Is there a way to perform 2-D image rotation by matrix multiplication?

In my understanding, unlike shifting and scaling, image rotation actually rotates the coordinates whereby interpolating the pixels at discrete positions. It is like a projection that discrete values ...
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1answer
153 views

Denoise images with wavelets

I try to understand what following algorithm from this gimp plugin does to denoise an image: ...
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1answer
106 views

Fourier transform possible on non-rectangular part of an image

Dear Signal Processing readers, I want to introduce 'noise' into parts of images. Until now, I worked with rectangluar images for a similar purpose and did the following, using (inverse) Fourier ...
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1answer
37 views

Problems filtering image with prewitt

I'm trying to filter an image vertically to get the edges, in MATLAB, but I get very different results from convultion and correlation. CODE: ...
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1answer
38 views

How can Recognize handwriting number [closed]

Which algorithms should use to recognize handwriting numbers from an image?
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1answer
198 views

How to detect the exception by SVM with openCV

I have implemented SVM by openCV. However, I have a problem about SVM with openCV. For example, I have six categories, but I just use "five" of them to train my SVM. When testing, I want my system ...
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2answers
82 views

Image Segmentation - Berkeley Dataset

I've been given an image from Berkeley dataset to segmentate. I am an undergrad student and so far I threw everything i know to this thing. But the colors are extremely close. I tried; Clustering ...
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2answers
58 views

How does 3D Time-of-Flight (TOF) camera work?

This is my first post in this forum! So Point me if anything is not clear! I want to know how TOF camera works? So I've done Google & read some nice explanation about How Phase difference between ...
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1answer
63 views

Sub pixel shift causes weird results

I am trying to shift an image on a subpixel level, with the method described here: ...
2
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2answers
59 views

convolution matrix for image scaling

Is there any way how to compute convolution matrix for Nearest Neighbor (bicubic, bilinear) image scaling (upscale/downscale)?
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32 views

SIFT Problem with producing first layer of first octave

[1]Distinctive Image Features from Scale-Invariant Keypoints D. G. Lowe Int. Journal of Computer Vision 60(2) (2004), pp. 91--110' I have read [1] for several times. In Section 3.3, there is a ...
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1answer
39 views

Image Projection with SIFT

Recently, I am thinking about a problem regarding image projection. I have a larger picture as bellow. I want to find the transformation matrix, x'=Hx. When the above image pass the transformation ...
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1answer
22 views

Haar transform definition

I am trying to understand Haar transform of simple vector of numbers. Some references I found say, that first level transform of $ X = (4,6,8,10,13,9,3,3)$ will be $\sqrt{2}(5,9,11,3, -1,-1,2,0)$. ...
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2answers
25 views

Changing camera and image properties to calibrate a camera

Is it OK to calibrate a camera using effects and filters such as increasing contrast and brightness etc. to improve the detection of corners of a chessboard? Even if the used mode for detecting the ...
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0answers
61 views

how to get segmented OPTIC DISC from retinal image?

i have been segmented some image of retina. but the result is not good as i hope. for one image i can get good segmentation, like this image my code is from some reference in internet, in below i ...
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9 views

Registering ensembles of images

I'm pretty new to image processing and have run into a bit of a problem with correcting experimentally-caused drifts in my images. In essence, I have a 2D matrix of images, where each image is ...
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0answers
9 views

What is arithmetic coding and how is it helpful in determining location map in an image?

I would like to know about arithmetic coding technique for location map determination in an image.The theoretical aspect of arithmetic coding and how it can be computed in matlab.
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1answer
76 views

Noise in Digital image

in Digital Image Processing restoration ,from my understanding after reading articles , it's seems that the noise must be dominant in the histogram of the image , which is make it possible , to get ...
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75 views

Image enhancement algorithms for adjusting shadow, exposure, contrast etc

For those who have either used Picasa/Photoshop, they would see different image enhancement options such as: Change exposure Change shadow Change highlights Change vibrance I have searched online ...
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1answer
204 views

How to improve an FFT AM demodulator for NOAA APT satellite imagery?

My question involves proper FFT Technique for AM demodulation, in the special case where the modulation rate exceeds the carrier frequency. This question has a specific hobbyist application, the ...
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1answer
55 views

A question about image compression with SVD - MATLAB

I have to compress an image by using svd. I did a few things but all of them produced gray image. However, Output must be rgb. How can i compress an image without changing its original format?
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1answer
134 views

Who is Barbara (test image)

In recent years I've started doing work in image analysis and have used the Barbara and Lena images. Early on I became aware of the interesting history surrounding the Lena image and that got me ...
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0answers
32 views

High Pass Filter, effect of applying it on this image.

I am having question about the HPF. In particular, it is having a high pass guassian filter which is applied to the original image below. High pass filter should only detect edge (lots of change in ...
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1answer
14 views

compute image contrast

I need to get information about contrast of an image, and I compute its value in this way: contrast=Pmax/Pmin where Pmax is ...