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.

learn more… | top users | synonyms

0
votes
0answers
4 views

Error in Visual Studio while trying to load image using OpenCV

I was trying to load an Image in Visual Studio 2013 (on 32-bit Windows machine), using OpenCV 2.4.10, but came across an error as: "Unable to start program 'C:\\Documents\Visual Studio ...
0
votes
0answers
10 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 ...
0
votes
1answer
20 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 ...
1
vote
1answer
29 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 ...
0
votes
0answers
9 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 ...
0
votes
2answers
34 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 ...
-1
votes
0answers
13 views

Embed a link within the Image [closed]

How can I embed a 3rd party link within an image which is automatically called once the image is opened through a web browser or website? The link literally calls out everytime the image is refreshed. ...
0
votes
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 ...
1
vote
2answers
43 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 ...
1
vote
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 ...
0
votes
0answers
24 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 ...
0
votes
0answers
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 ...
0
votes
0answers
15 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 ...
0
votes
0answers
22 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 ...
0
votes
3answers
21 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?
0
votes
1answer
40 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 ...
0
votes
1answer
27 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 ...
3
votes
1answer
147 views

Denoise images with wavelets

I try to understand what following algorithm from this gimp plugin does to denoise an image: ...
0
votes
1answer
89 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 ...
0
votes
1answer
26 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: ...
0
votes
1answer
37 views

How can Recognize handwriting number [closed]

Which algorithms should use to recognize handwriting numbers from an image?
0
votes
1answer
126 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 ...
1
vote
2answers
75 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 ...
0
votes
2answers
55 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 ...
1
vote
1answer
58 views

Sub pixel shift causes weird results

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

convolution matrix for image scaling

Is there any way how to compute convolution matrix for Nearest Neighbor (bicubic, bilinear) image scaling (upscale/downscale)?
0
votes
0answers
26 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 ...
1
vote
1answer
35 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 ...
0
votes
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 $\sqrt{2}(5,9,11,3, -1,-1,2,0)$. ...
1
vote
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 ...
1
vote
0answers
50 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 ...
0
votes
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 ...
0
votes
0answers
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.
0
votes
1answer
75 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 ...
0
votes
0answers
61 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 ...
1
vote
1answer
158 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 ...
-1
votes
1answer
49 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
1answer
117 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 ...
0
votes
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 ...
0
votes
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 ...
2
votes
1answer
56 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
1answer
69 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 ...
0
votes
0answers
532 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 ...
0
votes
0answers
28 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
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 ...
2
votes
2answers
172 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 ...
1
vote
3answers
69 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 ...
0
votes
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.
0
votes
3answers
209 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 ...
0
votes
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!