Questions tagged [classification]

is a system of grouping objects of study or observation in accordance with their common features. The classification problem is a formalized task in which a set of objects (cases), separated in some way to classes.

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16
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5answers
16k views

Scale and Rotation invariant feature descriptors

Can you list some scale and rotational invariant feature descriptors for use in feature detection. The application is for the detection of cars and humans in video captured by a UAV, using a multi-...
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3answers
26k views

Feature extraction for sound classification

I'm trying to extract features from a sound file and classify the sound as belonging to a particular category (eg : dog bark, vehicle engine e.t.c). I'd like some clarity on the following things : 1) ...
12
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1answer
16k views

Image classification using SIFT features and SVM

I am hoping someone can explain how to use the bag of words model to perform image classification using SIFT/SURF/ORB features and a support vector machine? At the moment I can compute the SIFT ...
12
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3answers
950 views

Texture Classification via DCT

How viable would it be to classify the texture of an image using features from a discrete cosine transform? Googling "texture classification dct" only finds a single academic paper on this topic, ...
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2answers
15k views

How do I retrieve texture using GLCM and classify using SVM Classifier?

I'm on a project of liver tumor segmentation and classification. I used Region Growing and FCM for liver and tumor segmentation respectively. Then, I used Gray Level Co-occurence matrix for texture ...
12
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2answers
518 views

What methodology to use for discrimination of different (musical?) tones

I am trying to research and figure out how best to attack this problem. It straddles music processing, image processing, and signal processing, and so there are a myriad number of ways to look at it. ...
11
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2answers
1k views

Good metric for qualitatively comparing image patches

I am trying to "match" little square patches in an image. At first glance, it seems reasonable to simply do a Euclidean distance style comparison of two of these arrays to get a "similarity" measure. ...
10
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3answers
5k views

Why transforming the data to a high-dimensional feature space in which classes are linearly separable leads to overfitting?

I read in my book (statistical pattern classification by Webb and Wiley) in the section about SVMs and linearly non-separable data: In many real-world practical problems there will be no linear ...
10
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1answer
737 views

How can I automatically classify peaks of signals measured at different positions?

I have microphones measuring sound over time at many different positions in space. The sounds being recorded all originate from the same position in space but due to the different paths from the ...
9
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1answer
341 views

Vehicle segmentation and tracking

I've been working on a project for some time, to detect and track vehicles in video captured from UAV's, currently I am using an SVM trained on bag-of-feature representations of local features ...
9
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1answer
340 views

Recognizing data clustered into shapes

I am working on a project in Python to detect and classify some bird song, and I have found myself in a position where I need to convert a wave file into frequency vs. time data. This hasn't been too ...
7
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3answers
1k views

How to classify accelerometer data?

I am trying to detect if a car did accelerate or did brake by using the accelerometer of the iPhone. In the figure below I plotted the collected data. (To collect the data the phone was laying flat ...
7
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2answers
423 views

How can I distinguish between two similar EEG signals?

I have two EEG signals that are very similar. The difference is only in amplitudes. However, they are coming from two different cognitive processes. What are some methods, beside FFT, for ...
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7answers
11k views

What are characteristics of shadows in an image given an outdoor setting from an image processing point of view?

I'm wondering what basic characteristics of shadows are. I'm looking from a camera image/video processing point of view. I'm considering the case of an outside scene in direct sunlight. These are the ...
5
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2answers
61 views

Finding filaments in high dimensional space

I have unit vectors in a high-dimensional space (~300) that are non-uniformly distributed over this hypersphere. There is physical meaning when the vectors are clustered together, but I'm ...
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4answers
1k views

What Kind of Features Can I Extract from this Signal

I want to monitor (automatic-)gearbox failures on some vehicles. For each vehicle I have a captured signal representing the selected gear at each one millisecond. An example of two signals are shown ...
4
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3answers
12k views

Best way to remove unwanted region from image

I am finding the techniques to remove unwanted regions (small dots) from image. I have an image that includes object and some unwanted region (small dots- see first image). I want to remove it. Hence, ...
4
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3answers
3k views

Detection of wobbling sound with rising notes

In an audio file I would like to find calls of a specific bird specie, one that makes wobbling sound with rising notes. Can you recommend what would be the best audio feature to calculate in time or ...
4
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1answer
2k views

From MFCC to Machine learning. What are the steps?

I was able to get a dataset with MFCC coefficients. However, depending on the length of my sound file I get a different sized matrix. As in, 13 (13 MFCC coefficients) by XXX, where XXX will vary ...
3
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2answers
6k views

Mahalanobis vs Normalization+Euclidean

I'm using a set of features extracted from a signal for classifying the data window with KNN algorithm. Since the features have different value ranges, their influence on distance calculation is ...
3
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1answer
2k views

KNN method for different values of K on a handwritten digit data set

We're supposed to use KNN (K Nearest Neighbor) method for different values of K to classify a handwritten digit data set. The problem is, this is the first time I want to do a project like that in ...
3
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1answer
6k views

MFCC feature vector from wav file

I am trying to implement a spoken language identifier from audio files, using Neural Network. I need to generate one feature vector for each audio file. From what I have read the best features (for ...
3
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1answer
172 views

Recognizing hand-written archaeological signs

I have 75 images of handwritten signs from which I extracted 7 Hu moments and solidity features. How can I find similarities among them to train a classifier and predict the value? I thought SVM was a ...
3
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1answer
2k views

Support Vector Machine: A non-probabilistic binary linear classifier

I read that SVM is a supervised learning method, it is also a non-probabilistic binary linear classifier. I understand why it is binary because it classifies our training pattern to two classes $w_1$ ...
3
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1answer
2k views

Python: Least Squares Support Vector Machine (LS-SVM)

I'm looking for a Python package for a LS-SVM or a way to tune a normal SVM from scikit-learn to a Least-Squares Support Vector Machine for a classification problem. The goal of a SVM is to maximize ...
3
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2answers
254 views

Which parameters should I take care of while converting .au to .wav for Genre Classification

I am learning to develop Music Genre Classification models. I have a dataset in which files are in ".au" format, which I need to convert into ".wav". I used SoX (Sound eXchange) to convert it. With a ...
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3answers
476 views

Low recognition rates using GMM for image classification

I want to use GMM for image classification. So, I have extracted SIFT features from each image in the corpus. Then, I apply EM algorithm to learn GMM parameters (I have coded it in matlab). I get ...
3
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2answers
271 views

Guidance/Brainstorming for a mapping/classification problem

I'm quite new to machine learning/data mining and I'm struggling to find the correct path for my problem and would appreciate some guidance or criticism of my proposed solution i.e. is there a better/...
3
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0answers
127 views

Grouping clusters using Mahalanobis distances

I need to know the "number of clusters" in a dataaset. To find the number of clusters, I am using a Gaussian Mixture model fitting, bear with me, Because the underlying distributions (each cluster) ...
2
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1answer
2k views

How to do people detection from bird eye view?

I'm trying to do people detection from bird eye view. Actually, it is not a normal bird eye view because I don't have RGB images but I have disparity map, depth map as well. In these kind of images, ...
2
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1answer
285 views

Can we determine if a filter is butterworth or chebyshev from its physical topology?

Can all analog filters be classified as Bessel, Elliptic, Butterworth or Chebyshev? Given a physical ladder topology of several stages of {L, C or LC} in {series or parallel}, is it possible to ...
2
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2answers
317 views

Detecting Central Axis (petiole/rachis) of a Pinnated Palm

I'm new in StackExchange and I'd appreciate some help. I'm working in an algorithm for detecting "aguajes", a particular kind of palm. So far, I got good results using a texture feature extractor and ...
2
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1answer
119 views

Pyramid Match Kernel: How to fit grid around data points?

I am planning to use Pyramid Match Kernel method for object recognition from depth images: I am going to extract a set of feature vectors $x \in \mathbb{R}^d$ for each object instance and then I want ...
2
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1answer
145 views

Classifying 2D shapes by the smoothness of their boundaries

I'm doing image analysis, and I want to classify smooth objects (has smooth boundaries) from non-smooth objects (has zigzag-like boundaries). Which feature should be fed into ML framework? What are ...
2
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3answers
211 views

What's a good classification algorithm for a large amount of classes?

My requirements are these: Fast classification of vectors of length 100 to one of 30000 classes Iterative learning (can improve the model after it was first learnt) Preferably available ...
2
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0answers
83 views

Obtaining n values from n-1 sensors

As the questions states, lets consider we have 3 gas sensors giving me data for: A B C Note that only sensors for A and B give absolute values, yet we need the absolute values for all four species:...
2
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0answers
52 views

Supervised instrument recognition

Is it possible to use NMF for a sort of supervised polyphonic instrument recognition? I have training data for a timpani and training data for a bongo (or a bongo, snare and box drum). How can I ...
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3answers
1k views

What does natural scene image data-set mean?

I came across a paper that is trying to classify and detect object(s) present in what they call a natural scene data-set. They have images containing objects like cars, bikes and people. Can anyone ...
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3answers
193 views

Need critical help: How to detect and distinguish two very similar looking signals?

Hi guys I have a really tough signal processing question here. How do you detect and distinguish two very very similar looking waves? I need to distinguish between these two signals for an online ...
1
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1answer
265 views

Missing Data in Machine Learning Classification

I have a training set of 4000 for ML with 36 features, two-class classifier. Consider that due to some discrepancy feature no. 25 is missing for half of the data. But during data acquisition I know ...
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2answers
275 views

Calculate lines of the Inverse of Autocorrelation Matrix

I need to calculate the inverse of a autocorrelation matrix $$\mathbf R_{xx} = E\left\{\mathbf x \mathbf x^T\right\}$$ Where the samples $\mathbf x$ are $266000\times 1$ vectors, which means I'll ...
1
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1answer
437 views

What would the target matrix to train Neural Network?

I'm new at Artificial Neural Network and I'm using MATLAB developing Facial expression recognition and There are six expressions ; I'm not able to understand about How to create a target matrix? My ...
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2answers
210 views

Detecting automobile honking

I'm detecting vehicle honking from environmental sounds (engine noise, speech music, siren etc.) based on binary classification. Common audio features (spectral flux, centroid, mfcc, harmonicity etc.) ...
1
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1answer
425 views

Understand about maximum a posteriori probability (MAP) in classfication task

I have a 2D image defined on a region $\Omega$. Let $I: \Omega \to R$ be a gray image. Assume that the region can be separated into $N$ sub-regions $\Omega_i$ such that $$\forall i,j=1,\ldots ,N:\...
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2answers
1k views

Using ICA on EEG signals for feature extraction

I am attempting to use ICA (FastICA via scikit-learn) on EEG signals from seven electrodes per subject for feature extraction and identity classification – that is to extract signal which is related ...
1
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1answer
338 views

Object Classification using pyramid match kernel

I have been reading up on the pyramid match kernel as an alternative to using the bag-of-words model for object classification using a SVM. The bag-of-words model provides a model for transforming a ...
1
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1answer
71 views

Video processing to detect a logo in frames

I am trying to detect a TV channel logo inside a video file, so simply given an input .mp4 video, detect if it has that logo present in all (or most) of frames or not (or maybe what percentage of ...
1
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1answer
115 views

Generate and Recognize Graphical Patterns

I'd like to develop an algorithm for recognizing and generating graphical designs. As an example, consider these examples from one class: class 1 example 2 http://185.49.85.137/Kave/up/Decorative-...
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1answer
90 views

Separate key-related frequencies from audio signal

I have various samples of various instruments sound, and I'm trying to classify them using pyAudioAnalysis and various Machine Learning algorithms. The samples ...
1
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1answer
2k views

How we calculate Precision-Recall Curve?

As far as I know, precision and recall are two single values. How we can plot a curve from these two single values? I think I should calculate a set of values for each of them but how? afterwards, ...