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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32 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
25 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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52 views

Denoise images with wavelets

I try to understand what following algorythm from this gimp plugin does to denoise an image: ...
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1answer
70 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
17 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
35 views

How can Recognize handwriting number [closed]

Which algorithms should use to recognize handwriting numbers from an image?
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1answer
61 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
67 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
53 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
55 views

Sub pixel shift causes weird results

I am trying to shift an image on a subpixel level, with the method described here: ...
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2answers
55 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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23 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
32 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
24 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
40 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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0answers
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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8 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
73 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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0answers
49 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
128 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
41 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
103 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
30 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
12 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 ...
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1answer
55 views

Avoiding edge repeats in a FFT convolution

I am trying to use FFT as a fast way to convolve a image, however one of the downsides of this is that the "kernel" image will repeat when reaching the edges of the sample. Is there a way to avoid ...
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1answer
63 views

Explain Shift property of DFT

Please check the link What effect does a delay in the time domain have in the frequency domain? Here it is said that if you delay your input signal by D samples, then each complex value in ...
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0answers
374 views

Radon Transform Implementation In Matlab

I know MATLAB has a built in Radon function, but I am working on implementing the radon transform in order to perform filtered back projection. As I started, my idea was multiple nested for loops for ...
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0answers
21 views

Using morphological operations for color images processing

Have you ever seen any articles about using morphological-like technique for denoising color images?
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0answers
15 views

Image Registration Accuracy

I am doing image registration of aerial images with ground reference image. To extract the accuracy measure, one would have to obtain some sort of ground truth manually via selecting tie-points ...
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2answers
146 views

Calculation of sampling rate and its effect on an Image?

I know that for a given signal, the sampling frequency $F_s$ must be twice or more than maximum frequency of the signal $F_m$. It is easy to understand the concept for a 1D signal. But I don't know ...
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3answers
64 views

float image to integer type image

I have a multispectral satellite image and I would like to "transform" each of the image bands into one with integer values. For example to stretch? the image between 0 and 255. Not sure how to ...
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0answers
37 views

What filters used in this picture?

What filters are used to get an image like one on the left? I need to find body pose of a person in a picture.
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2answers
161 views

2D-otsu algorithm in Digital image processing

I'm working on image project using Matlab & I heard about 2D-otsu algorithm as effective segmentation with low SNR and low contrast images, but I can't find enough information about it or how to ...
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0answers
9 views

image recording

Can I know the delay between the time the PC receives the image and the time when it was acquired? I will record video with time stamp, which software it better for recording? Thank you!
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2answers
60 views

Ship detection from aerial image

I have an aerial image, like this I want to detect the outline of the ship without shadow. How can I do it? I tried threshold in both graylevel, RGB and HSV. It doesn't work perfectly.
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3answers
92 views

How to filter noise from continuous path in image

Problem statement In the dataset above, you can notice a continuous path and then a noise-band at around 320-400 on the x-axis. I want to be able to apply a filter that amplifies the continuous ...
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1answer
55 views

How to detect a inhomogeneity region in image

I have an image that includes object and background. However, the object appears some inhomogeneity region due to illumination. My work is that how to detect inhomogeneity region. Which is feature can ...
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2answers
171 views

Draw outline of a text in an image

I need to draw an outline of text in an image. Consider the below image as an example. Can anyone suggest me a direction to achieve this? I don't have experience in image processing. Any tools/lib ...
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0answers
28 views

Affine Parameter Optimization using simulated annealing

I am working on a project to compare images in the database. I use color and gradient orientation as features of the image and these features are not rotation invariance, therefore to compare well I ...
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1answer
188 views

An alternative algorithm for blob detection

Here's a sample image of my experiment which is to be processed for finding the information of all the blobs (centre, dimension etc.). Basically the image contains some noise, few bold lines, and of ...
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1answer
56 views

Longest line inside of 3D object

I have a 3D object which I have segmented and represented as a 3D binary array. I need to find the longest line which fits inside of the object in three dimensional space. What would be an efficient ...
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1answer
30 views

which spatio-temporal properties does dynamic textures exhibits?

know that dynamic textures are spatially repetitive and temporally varying patterns. 1.I read one sentence in one paper i.e. They are sequences of frames exhibiting certain stationarity properties ...
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0answers
43 views

Impact of different padding schemes in Frequency domain image filtering

I understand, that image padding is necessary in order to prevent wrap-around effects due to circular convolution. My set of questions are related to different padding schemes. Zero Padding is easy ...
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2answers
140 views

How can I go forward with this image processing task?

0 down vote favorite I am totally new to Image processing. I just started my Master thesis in the area of Computer vision and Machine learning. My background is Informatics. Now, my first task is to ...
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0answers
48 views

what is the starting time of FRAME VALID in CMOS MT9V131 Sensor?

I am going to start my project with CMOS MT9V131 Image sensor. In that, data output timing diagram, I have some doubts. Actually, I am going to interface this sensor with LPC1768 by the use of I2C ...
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1answer
93 views

What is the Difference between Texture and Image?

I am beginner in the image processing I want to know what is difference between Texture and Image? or whether they are same? can anyone explain it. Also,if i want to do texture segmentation,can i ...
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0answers
31 views

What is weakness of entropy image

I often see that entropy is used in image segmentation area. Hence, I have a question about entropy. What is weakness of entropy image. Which case is fail when apply entropy image? Thank you so much
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1answer
48 views

Thresholding a difference image with a very high kurtosis

I have an difference image produced by substracting two images of a certain location taken a two different time steps. The resulting image of this operation shows a histogram with a very large peak ...
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1answer
80 views

Dynamic Textures

i know that texture refers to surface characteristics and appearance of an object given by the size, shape, density, arrangement, proportion of its elementary parts. But i am more interested in ...