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

learn more… | top users | synonyms

0
votes
1answer
10 views

Why doesn't JPEG use 1D DCT for image compression?

I know that JPEG uses 2D dct and splits the images in 8x8 blocks. Why doesn't it simply split the image in one-dimensional vectors in $\mathbb{R}^{64}$? Wouldn't it simplify the math? My guess is that ...
1
vote
0answers
28 views

Laplacian Operator with and without diagonal direction

This is a general question on the laplacian operator, which has two different versions. The first version is : \begin{matrix} 0 & 1 & 0 \\ 1 & -4 & 1 \\ 0 & 1 & 0 ...
1
vote
0answers
28 views

Size obtained by applying Linear convolution

We know that applying a filter on an image is called correlation or convolution depending on the filter angle. In Gonzalez I have read that we can apply linear convolution on an image. Here I have a ...
0
votes
0answers
3 views

What does non-parametric sampling mean in Texture Synthesis?

can I get a simple explanation of what non-parametric sampling mean in the area of texture synthesis? I can't get a relevant explanation of it. For example, the paper by Heeger and Bergen (1995) is ...
-1
votes
1answer
15 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?
1
vote
2answers
103 views

[2D fourier transform]: Most people can't explain this

I am confuse of 2d magnitude plot of the spectrum frequency. So we have 2 images, the first one is shown at the top, and the expand version of the white box is shown at the second row. For the ...
0
votes
1answer
71 views

Inverse fourier transform by using a random phase and an original magnitude (matlab)

I want a image. Firstly I want to do fourier transform and get the magnitude and phase information. And then make a new random phase, finally use the changed random phase and original magnitude to ...
1
vote
2answers
25 views

LoG filter creating additional maxima in scale space

To create a scale space, I applied a Laplacian of Gaussian filter on the following image: After the scale space was created, I plotted circles around local maxima in scale space. However, instead ...
0
votes
1answer
19 views

Smooth X,Y,Z data with discontinuous, artificial jumps

I have some data $(X,Y,Z)$, which is a set of measurements $Z$ over a $2D$ space $X$,$Y$. The $Z$ data on this space is continuous except for some discontinuous jumps in certain domains of $X$,$Y$ ...
1
vote
2answers
53 views

how to detect corner in a digital image using MATLAB? [on hold]

I am designing an algorithm for image processing. I am using MATLAB for the processing of the images(video). How I can detect the position of the corners in the image?
0
votes
1answer
40 views

Computer Vision / Speech Recognition

I am not sure if the question is off topic but I need some input before I can finalize anything. Actually to do my higher studies (in research) I wanted to make sure that I land my career in Digital ...
0
votes
1answer
44 views

Beginner's Books [duplicate]

I come from a background of computer science and I got interested in image processing but it requires a lot of signal processing, so could someone provide me a good beginner's book, that maybe first ...
0
votes
0answers
18 views

watermark embedding using 2d arrays

I have LL2 in a 2D array.(extracted after a 2-level DWT). And watermark W1 also in a 2D array.(a binary image, which only contains 0s and 255s). I need help regarding embedding the W1 in LL2 according ...
0
votes
1answer
30 views

Frequency of the wave in frequency domain

If we have a 1-dimensional wave in time domain, it can be represented in frequency domain with x axis indicating the frequency of the wave and y axis indicating amplitude/magnitude of the wave. But ...
0
votes
0answers
23 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 ...
1
vote
1answer
42 views

Frequency Spectrum of an image

I have been studying about Frequency Domain from many days but still i am not able to clear one of the confusion. We say that in frequency domain an image is represented as waves. What I am able to ...
0
votes
1answer
20 views

Skeleton from distance map

Can anyone give some tips how to obtain Skeleton from distance map? I already managed to obtain skeleton using erased method (e.g. zhang suen) but it's time consuming because it's an iterative method ...
0
votes
1answer
38 views

Classifying animated GIFs as animation or film

Is there any known way of differentiating between frames of real footage and animated content? It seems like there's probably range of colors more likely to appear in a histogram for real footage, or ...
0
votes
0answers
25 views

Getting error in PSNR calculation using Matlab

I want to find out PSNR and SNR values of two images A and B of same dimension in Matlab.I used the following code [peaksnr, snr] = psnr(A,B) and getting an ...
0
votes
0answers
10 views

Switching gradient computation in Lucas-Kanade pyramidal feature tracking

The following refers to pyramidal Lucas-Kanade. Given two images $I$ and $J$, we wish to find point $v$ in $J$ which corresponds to point $u$ in $I$. The initial step of the algorithm requires ...
0
votes
1answer
30 views

Image getting completely white on downsampling

I performed an image downsampling with averaging operation(The image is divided into 2 by 2 blocks,then it is downsampled by 4 times.New pixel values od downsampled image is replaced with the mean of ...
0
votes
0answers
20 views

DCT Quantization Dark Image

I am trying to quantize a image after applying dct to a raw image.. But i am getting a dark image as the output.. What am i doing wrong.... I thought that adding a constant value across the whole ...
0
votes
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 ...
0
votes
1answer
9 views

Equal contribution criteria during image pyramid construction

In their paper on Image Pyramids, Burt and Adelson state the following about pyramid generation. An additional constraint is called equal contribution. This stipulates that all nodes at a ...
2
votes
1answer
49 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 ...
0
votes
0answers
16 views

Sliding Windows, Global Image, Clustering and …?

Imagine that you have an algorithm that must detect some feature in an image. Right now, I know three "families" of search algorithms. Sliding Windows: You take a patch of some size (e.g. 15x15 ...
0
votes
1answer
50 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 ...
-1
votes
2answers
28 views

Implementing image chroma keying with FIR filter in MATLAB

Is there any way I can apply the concept of FIR filters in chroma key composition, where I will remove a green background to focus on a subject and replace a different image on the removed part, sort ...
0
votes
1answer
28 views

Stopping Viola Jones Face Detection early

I want to try to improve an image processing technique for finding faces in images. I want to stop the Viola Jones face detector before it finds all faces, and do histogram equalization and other ...
0
votes
2answers
34 views

What is a translation property in DFT

Hi someone please explain me the translation property of DFT. I am not able to understand it neither from Gonzalez nor from internet. I have done extensive study on this but not able to get it. Really ...
2
votes
2answers
47 views

Would the locations of SIFT features generally agree with features detected by Shi-Tomasi method?

I am having a comparison of different feature detection methods. So if we compare the SIFT (Scale-invariant feature transform) and Shi-Tomasi method, will their feature locations agree and why? Are ...
0
votes
2answers
31 views

image processing in matlab

We try to multiplication operation bw(black-white) image with rgb image in same image but it's class is not same(bw-> logical, rgb->uint8) so not complated successfully. How can do convert from ...
0
votes
0answers
16 views

Stationary wavelet transfrom: diagonal detail response

I am using the PyWavelets library to take the stationary wavelet transform of some images. By looking at the documentation for the stationary wavelet transform, I notice that for each scale level it ...
-1
votes
0answers
34 views

Removal of skull stripe from MR image

How to remove the skull stripe from an MR image and to get the csf part from the image clearly? ...
1
vote
1answer
29 views

Image correlation confidence measure

I am trying to calculate the disparity between stereo image pairs. I'm using what appears to be the standard approach of correlating between a window of pixels from one image and a sliding window ...
2
votes
1answer
85 views

Bicubic Interpolation

I'm trying to do bicubic interpolation on an 8*8 matrix(image) shown below. ...
1
vote
3answers
149 views

Discrete version of pillbox function

This is an image processing question. In 2-D Euclidean space a pillbox function, $f(x)$ is given by: $$f(x,y) = 1\text{ if } x^2 + y^2 < R, 0 \text{ otherwise } $$ $R$ is come constant. If I ...
0
votes
0answers
19 views

Bhattacharyya distance for image segmentation explanation

I have a question need some your suggestion. I spent 2 months to resolve that problem but the result is not so good. Hence, I would like ask you some thing about my implementation. My goal is that I ...
0
votes
0answers
24 views

Gabor filter bank spatial frequency parameters

I've been trying to learn about using Gabor filters to extract features from an image. There are some research papers that list their spatial frequency parameter in the form of x:y cycle per pixels in ...
0
votes
0answers
14 views

Using morphological operations for color images processing

Have you ever seen any articles about using morphological-like technique for denoising color images?
0
votes
1answer
28 views

Avoid saturated pixels in cross-correlation computation

I am doing template maching using Normalized Cross-Correlation for measuring similarity between template and image. However, some images from my dataset contain saturated pixels (overshoot) which ...
0
votes
0answers
30 views

Image Processing - Identifing/locating Random Solid Blocks of Colour

I am not overly familiar with image processing. I know a little about it from University, but I have not really done any for a while and I have found myself with a problem that requires it. What I ...
0
votes
0answers
17 views

Detecting inset images/videos from a video

I want to detect multiple rectangles in a video, each of which features a different content, but running simultaneously. This is typically seen during debates on news channels. For example, in the ...
3
votes
2answers
41 views

Algorithms for deformable image registration

I need to perform a deformable image registration (DIR) for delineation of the different brain parts on the brain MRI 3D image. I faced with a problem that there are a lot of different approaches for ...
1
vote
2answers
70 views

how can i get to know the frequency of a speech signal?

What is the actual meaning of frequency? what if the signal is aperiodic?? In general, we say that frequency means the repeatition of an event in unit time. But what about a speech signal? how can we ...
0
votes
0answers
23 views

Is pixel with resolution 100mX100m equal to four 50mX50m while covering same area?

I take an image with spatial resolution 100mX100m,I take the same image with spatial resolution 50mX50m then each pixel value in first image equal to some of four images when covering same area with ...
0
votes
0answers
15 views

Stegnography and cryptography

I am last year student working on the project: Separable reversible data hiding technique In encrypted image. What are the algorithms that we can apply on jpeg/png image for compression which ...
2
votes
1answer
85 views

O(1) peak segmentation algorithm in matlab?

I have an intensity image, similar to the image below. I would like to very quickly, segment this image, into separate peaks. Where each peak is labelled, and segmented. A notional segmentation of ...
1
vote
0answers
38 views

Gonzalez question solution

If I have the histogram of an input image as Gaussian probability density function of the form: $$P_r(r)=\dfrac{1}{\sqrt{2\pi}\sigma}e^{-\dfrac{(r-\mu)^2}{2\sigma^2}} $$ where: $\mu$ and $\sigma$ ...
-3
votes
1answer
37 views

What is difference between Taylor series and Legendre polynomial?

As i know, taylor series is used for analysis f(x). So if i have many orders, i can approximate f(x). In this point of view, what is difference Legendre Polynomials?