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-1
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0answers
11 views

OpenCV: How to focus camera only on required area [on hold]

I want to detect the face using VJ's algorithm in OpenCV and it's working fine, but I want to focus only on the region where face is detected not any other thing form the video stream.
0
votes
0answers
24 views

Improving MSE as fitness function for a genetic algorithm

I am implementing an autoencoder neural network in matlab, the weights of which are being optimised by a genetic algorithm. At the moment I am working on the first layer, trying to get an improved ...
3
votes
1answer
46 views

Extracting features for texture classification

I m a beginner in the field of pattern recognition and computer vision. I m working on a project right now to classify t-shirt patterns into three categories i.e. solids, stripes and checks. I have ...
-1
votes
1answer
39 views

Selecting a M.S. in CS focus [closed]

I need to pick a focus in my Masters program. The running candidates are Networking Bioinformatics Data mining Computer Image Recognition In order to avoid this becoming a discussion, I'd be ...
3
votes
1answer
49 views

Training and testing image sizes for classification in computer vision

When training a classifier for object detection using features extracted from images (eg HoG features), how important is it that the images used for training fed into the classifier in their natural ...
2
votes
1answer
98 views

Method to recognize abstract objects such as hand-drawn objects?

My research is in the area of Document Image Analysis. To be specific, the topic of my thesis is to automatically recognize and index characters in a set of hand-drawn objects, e.g. given a volume of ...
5
votes
2answers
47 views

What are all the differences between the Gibbs phenomenon artefects and JPEG artefacts?

I thought the Gibbs phenomenom is the result of Fourier analysis estimation (but was it Fourier Series estimation or can it also be Fourier Transform estimation?) JPEG uses the Discrete cosines ...
2
votes
1answer
40 views

Resizing and aliasing in computer science [closed]

If you resize an 1000x1000 raster image to 10x10 and resize it back to 1000x1000 is this considered to be an example of aliasing?
7
votes
1answer
38 views

Recognizing waterways in an aerial photo — polygons from edge detection images

I am trying to recognize waterways from aerial photographs (say from Google Maps). Local governments often have GIS data that says where the waterways (and roads, buildings etc) are, but the water ...
3
votes
2answers
29 views

How do I apply patch sized features to larger images?

I've been trying to teach myself some machine learning, and I wanted to ask what seems a simple question, but I've not been able to find any resources that explain the next step. Let's say I am doing ...
1
vote
1answer
37 views

How to compute Gabor feature vector?

I'm working on semi automatic texture segmentation using level set and gabor feature vector described by Manjunath und Ma [1]. I consider their feature representation is better than others since I ...
0
votes
1answer
102 views

Number of different output labels in Local Binary Pattern

I'm studying about Local Binary Pattern and I'm having trouble understanding the following part about the number of output labels for binary patterns from Computer Vision using Local Binary Patterns, ...
2
votes
1answer
99 views

How to count near circular objects in image

I have a image similar to below. In that I need to find all red circles and count them. So, I am thinking to use MATLAB R2011a with Image Processing Toolkit for it. How could I possibly extract them? ...
2
votes
1answer
45 views

How to evaluate the accuracy of a method for the extraction of the principal lines of the palmprint

Let's assume that I've implemented a method for the extraction of the principal lines of the palmprint. For instance, let's say that I'm able to do a transformation like the following one (image from ...
2
votes
4answers
80 views

Environment detection - How to detect “city” versus “landscape” background environment in computer vision?

I'm searching for computer vision or machine learning algorithms/methods that are used to classify or differentiate two outdoor environments. Given an image with vehicles, I need to be able to detect ...
1
vote
1answer
68 views

Making feature vector from Gabor filters for classification

My aim is to classify types of cars (Sedans,SUV,Hatchbacks) and earlier I was using corner features for classification but it didn't work out very well so now I am trying Gabor features. code from ...
3
votes
1answer
43 views

Environment requirement in training image dataset for classifier

I have a question about preparing the dataset of positive samples for a cascaded classifier that will be used for object detection. As positive samples, I have been given 3 sets of images: a set of ...
2
votes
1answer
155 views

Which algorithms are usable for heatmaps and what are their pros and cons

This is a cross post from Stack Overflow, and DSP at Stackexchange since I cannot really decide which part of Stackexchange is most fitting. If this is the wrong place please tell me and I'll remove ...
1
vote
1answer
54 views

Job sites for applied/interdisciplinary mathematics related to computer science? [closed]

I'm looking for job sites in applied/interdisciplinary mathematics, more specially, say postdocs or higher positions in mathematics and medical imaging, mathematics and computer vision. I'm aware of ...
2
votes
2answers
150 views

Object recognition - given an image, does it contain a particular 3D object of interest?

I have in mind a particular 3D object. Given an image taken by a camera, I want to check whether that image contains an instance of my object. For instance, let's say that the object is a bathroom ...
5
votes
1answer
288 views

Deriving the Sobel equations from derivatives

Many sites give the Sobel operators as the convolution mask for smoothing an image. However, I haven't found a single site that describes how you can derive the operators from partial first ...
3
votes
5answers
728 views

Where can a student learn image processing?

I am a student of computer science with interest in image processing. I have learned how to apply a few effects to images like making them grayscale, sketching them out of lines, etc. I would like ...
5
votes
1answer
401 views

circle packing algorithm used by Percolator

I was admiring this rendition of the Mona Lisa from quasimondo's Flickr account. He says: Combining circle packing with data visualization. The pie charts show the distribution of the dominant ...
1
vote
1answer
42 views

How can you see which points in the spectrum is from which pixel in the original image?

Take the image and spectrum below. If I look at the spectrum, it just look like noise.... How to make sense of it intuitively? Image: Frequency spectrum of image (using Fourier Transform):
2
votes
1answer
301 views

What the difference between the Fourier Transform of an image and an image histogram?

Consider this small picture of a sunflower, and its histogram: What would the Fourier transform of the first picture look like? Is there any relationship between the histogram and the Fourier ...
0
votes
0answers
79 views

Aproximation algorithm for histogram

This is my first question, so please, be soft on me. I have a following problem: I'm a programmer not a mathematician, I don't often understand pure mathematical language and marks or symbols, I ...
1
vote
0answers
69 views

2D convolution: Flipping the kernel?

Why do we need to flip the kernel in 2D convolution in the first place? What's the benefit of this? So, why can't we leave it unflipped? http://www.songho.ca/dsp/convolution/convolution2d_example.html ...
1
vote
1answer
113 views

Identifying an object in an image based on color (AI ?)

First off, I am not sure if this is the correct stackexchange site to ask this question on, so moderators can feel free to move it. I am working on an application that identifies an object in an ...
4
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0answers
131 views

Space filling between random 2D lines

Note that I had asked this question in GIS forum, although it has gotten many up-votes, still has not received any answer. Hope you can break the silence, some collaboration :) Consider a ...
7
votes
2answers
786 views

Why is the laplace transform not popular for image processing convolution?

Why is the laplace transform not popular for image processing convolution? Most textbooks only conver the Fourier transforms.
2
votes
2answers
99 views

Mathmatical way to represent an image kernel?

How to represent the calculation in this image mathematically? For example: With the discrete convolution $(f * g)[n]\ \stackrel{\mathrm{}}{=}\ \sum_{m=-\infty}^\infty f[m]\, g[n - m]$ and Fourier ...
9
votes
1answer
142 views

How to detect sunshine on a photo

How would you algorithmically detect for any given photo whether the sun was shining when the picture was taken? Examples A sample from this webcam at a mountain top: Clearly the sun is shining. ...
3
votes
0answers
147 views

Stereo images rectification and disparity: which algorithms?

I'm trying to figure out what are currently the two most efficent algorithms that permit, starting from a Left/Right pair of stereo images created using a traditional camera (so affected by some ...
1
vote
1answer
252 views

Image pattern detection - Finding similarities in same image

The problem: Only pattern-like images are supposed to be uploaded and be used as backgrounds to a site, photos should not. How would you detect if an image looks enough like itself to be regarded as a ...
1
vote
1answer
306 views

How do convolution matrices work?

How do those matrices work? Do I need to multiple every single pixel? How about the upperleft, upperright, bottomleft and bottomleft pixels where there's no surrounding pixel? And does the matrix work ...
3
votes
2answers
66 views

How center the eyes of human face at specific pixels?

I am facing a problem with processing some frontal facial images. I need to adjust the centers of the eyes (irises) to be at certain specific pixels in the image. In other words, i need to transform ...
1
vote
1answer
33 views

Transform inverse result

let us assume that: f is a grayscale image of size NxN, and F is the Fourier transform of f. G is a 2Nx2N transform obtained by inserting 0 between every value in F: What is the inverse transform ...
0
votes
2answers
302 views

median filter one after the other

Operate on an image by performing Median Filtering in a 3x3 window. Operate on the resulting image by performing, again, Median Filtering in a 3x3 window. Can the resulting image be obtained from a ...
1
vote
1answer
69 views

Contrast vs. Brightness question

As part of my homework I need to prove or disprove that changing the contrast and than changing the brightness is, or isn't the same as changing the brightness and after that changing the contrast. ...
2
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0answers
125 views

Compare vectors, photo mosaic

I’m trying to make a photo mosaic web application. I split the main picture in to a number of squares. I split this square up in to 9 squares (See picture) Then I calculate the mean color (RGB) of the ...
5
votes
2answers
4k views

DIfferences between computer vision and image processing

I am basically an Electronics and Communication Engineering student. My relevant coursework include Probability Theory and Stochastic Processes, Engineering Mathematics, Signals and Systems, Digital ...
0
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0answers
37 views

Contrasting object and background

When dealing with thresholding in digital image processing, what do the following terms mean? contrasting object contrasting background
6
votes
3answers
3k views

Shannon's entropy for an image

Shannon's entropy [plog(1/p)] for an image is a probabilistic method for comparing two pixels or a group of pixels.Suppose an image with a matrix of 3x3 has pixel intensity values ...
3
votes
2answers
311 views

Difference between HSI and YCbCr for pattern recognition by color

I am doing a project on face detection in C#. I want to find the skin area by using skin color segmentation. For that purpose, I have to extract the skin area. I know I can use HSI or YCbCr, but what ...
2
votes
1answer
100 views

Which Is a Better Way of Obtaining Scales, Gaussian Blur or Down Sampling?

In computer vision, scales are important when we carry out a scene analysis. Choosing different scales affect the result of the analysis. For example, if a face is relatively small in the scene, then ...