For some time, I have been using OpenCV. It satisfied all my needs of feature extraction, matching and clustering(k-means till now) and classification(SVM). Recently, I came across Apache Mahout. But, most of the algorithms for machine learning are already available in OpenCV as well. Are there any advantages of using Mahout over OpenCV if the work relates to Videos and Images ?
This question might be put on hold since it is opinion based. I still want to add a basic comparison.
OpenCV is capable of anything about vision and ml that is possibly researched, or invented. The vision literature is based on it, and it develops according to the literature. Even the newborn ml algorithms -like TLD, originated on MATLAB- (http://www.tldvision.com/) can also be implemented using OpenCV (http://gnebehay.github.io/OpenTLD/) with some effort.
Mahout is capable, too and specific to ml. It includes not only the well known ml algorithms, but also the specific ones. Say you came across to a paper "Processing Apples with K-means Orientation Filtering". You can find OpenCV implementations of this paper all around the web. Even the actual algorithm might be open source and developed using OpenCV. With OpenCV, say it takes 500 lines of code, but with Mahout, the paper might be already implemented with a single method making everything easier
An example about this case is http://en.wikipedia.org/wiki/Canopy_clustering_algorithm, which is harder to implement using OpenCV right now.
Since you are going to work with image data sets you will need to learn about HIPI, too.
To sum up, here is a simple pro-con table:
know-how (learning curve): OpenCV is easier, since you already know about it. Mahout+HIPI will take more time.
examples: Literature + vision community commonly use OpenCV. Open source algorithms are mostly created with C++ api of OpenCV.
ml algorithms: Mahout is only about ml, whereas OpenCV is more generic. Still OpenCV has access to basic ml algorithms.
development: Mahout is easier to work with in terms of coding and time complexity (I am not sure about the latter, but I reckon it is).
Related
I have started using Julia.I read that it is faster than C.
So far I have seen some libraries like KNET and Flux, but both are for Deep Learning.
also there is a command "Pycall" tu use Python inside Julia.
But I am interested in Machine Learning too. So I would like to use SVM, Random Forest, KNN, XGBoost, etc but in Julia.
Is there a native library written in Julia for Machine Learning?
Thank you
A lot of algorithms are just plain available using dedicated packages. Like BayesNets.jl
For "classical machine learning" MLJ.jl which is a pure Julia Machine Learning framework, it's written by the Alan Turing Institute with very active development.
For Neural Networks Flux.jl is the way to go in Julia. Also very active, GPU-ready and allow all the exotics combinations that exist in the Julia ecosystem like DiffEqFlux.jl a package that combines Flux.jl and DifferentialEquations.jl.
Just wait for Zygote.jl a source-to-source automatic differentiation package that will be some sort of backend for Flux.jl
Of course, if you're more confident with Python ML tools you still have TensorFlow.jl and ScikitLearn.jl, but OP asked for pure Julia packages and those are just Julia wrappers of Python packages.
Have a look at this kNN implementation and this for XGboost.
There are SVM implementations, but outdated an unmaintained (search for SVM .jl). But, really, think about other algorithms for much better prediction qualities and model construction performance. Have a look at the OLS (orthogonal least squares) and OFR (orthogonal forward regression) algorithm family. You will easily find detailed algorithm descriptions, easy to code in any suitable language. However, there is currently no Julia implementation I am aware of. I found only Matlab implementations and made my own java implementation, some years ago. I have plans to port it to julia, but that has currently no priority and may last some years. Meanwhile - why not coding by yourself? You won't find any other language making it easier to code a prototype and turn it into a highly efficient production algorithm running heavy load on a CUDA enabled GPGPU.
I recommend this quite new publication, to start with: Nonlinear identification using orthogonal forward regression with nested optimal regularization
I am doing a project on expression recognition in opencv and have successfully extracted the face region,i am having trouble building my own algorithm for the feature points extraction of a face,can someone help me with it?
since this is my first try to answer question, I will try to do my best. I cannot post more than two links, so I will try at least to give some hints.
Your question is quite broad. It depends on the type of application and requirements. Are you doing on-line detection, is it static etc.? Based on that, you should consider keypoint detection algorithm. I do not think it is a good idea to build your own algorithm, because OpenCV already has a lot of methods that you can choose from. All you have to do in most cases is to do some pre-processing, but it depends as well.
Most popular feature detection methods are: SURF (Opencv SURF), SIFT, ORB, FAST etc. Keep in mind that SURF and SIFT ar non-free. SURF and SIFT brings a lot of features and are quite accurate, somewhat scale and rotation invariant, but also a bit slow (especially on online tracking). FAST and ORB are fast, but they are more sensitive to noise and have their own disadvantages (see descriptions on OpenCV documentation). If I were you, I would try most of them and see which one does the best job (it is not difficult to test them).
Secondly, you have to choose descriptors. Very goog introduction is here:
Descriptors tutorial. There you will find all basic info. It is important to say, that you can mix various keypoint detection algorithms and feature description algorithms (but keep in mind that not all are compatible, tutorial will explain this).
I am out of links for this post, but OpenCV documentation provides a lot of sample code for this problem, so go ahead and have a look.
Hope you succeed. Good luck.
I am implementing active ASM/AAM using OpenCV for segmentation of face images using OpenCV (to be further used in face recognition). I am pretty much done with the canonical implementation of ASM (as per T. Cootes papers) and result I get is not ideal, it does not always converge and when it does some boundaries are not captured, which I believe is a problem in the modeling of a local structure - i.e. gradient profile matching.
Now I am a bit unsure what to do next. ASM is a simpler and computationally less intensive algorithm compared to AAM. Should I continue improving ASM(say for example using 2D profiles rather than 1D profiles, or use different profile structure for different type of lanmarks) or get my hands straight on AAM?
Edit: Also, what are the papers you could recommend that improve on the original work by T.Cootes? I know there are so many of them, but maybe there are techniques that are considered canonical today?
You can find clarifications and implemented AAM whith 2D profiles in the book "Mastering OpenCV with Practical Computer Vision Projects" by Packt Publishing 2012. A lot of projects described in this book are open source and can be downloaded here: GitHub. They are more advanced than T.Cootes implementation.
I can say that AAM (as existing implementation you can look also at vosm) have good convergence (better than ASM) only if you train it on the same man (very good results for example for FRANCK (Talking Face Video) sequence) in other cases ASM works better.
I am currently working on a project where I have to extract the facial expression of a user (only one user at a time) like sad or happy.
There are a lot of programs/APIs to do face detection but I did not find any one to do automatic expression recognition.
The best possibility I found so far:
-Using Luxand FaceSDK, which will give me access to 66 different points within the face, so I would still have to manually map them to expressions.
I used OpenCV for face detection earlier, which was working great, so If anyone has some tips on how to do it with OpenCV, that would be great!
Any programming language is welcome (Java preferred).
Some user on a OpenCV board suggested looking for AAM (active apereance models) and ASM (active shape models), but all I found were papers.
You are looking for machine learning solutions. FaceSDK looks like a good feature extractor. I don't think that there will be an available library to solve your specific problem. Your best bet is to:
choose a machine learning framework (SVM, PCA) with a java implementation
take a serie of photos and label them yourself with the target expression (happy or sad)
compute your model and test it
This involves some knowledge about machine learning.
I was trying to build a basic Face Recognition system (PCA-Eigenfaces) using OpenCV 2.2 (from Willow Garage). I understand from many of the previous posts on Face Recognition that there is no standard open source library that can provide all the face recognition for you.
Instead, I would like to know if someone has used the functions(and integrated them):
icvCalcCovarMatrixEx_8u32fR
icvCalcEigenObjects_8u32fR
icvEigenProjection_8u32fR
et.al in the eigenobjects.cpp to form a face recognition system, because the functions seem to provide much of the required functionality along with cvSvd?
I am having a tough time trying to understand to do so since I am new to OpenCV.
Update: OpenCV 2.4.2 now comes with the very new cv::FaceRecognizer. Please see the very detailed documentation at:
http://docs.opencv.org/trunk/tutorial_face_main.html
I worked on a project with CV to recognize facial features. Most people don't understand the difference between Biometrics and Facial Recognition. There is a huge difference based on the fact that Biometrics is mainly based on histogram density matching while Facial Recognition implements this and vector support based on feature recognition from density. Check out the following link. This is the library you want to use if you are pursuing CV and Facial Recognition: www.betaface.com . Oleksander is awesome and based out of Germany, but he answers questions which is nice.
With OpenCV it's easy to get started with face detection. It comes with some predefined sets for feature detection, including face detection.
You might already know this one: OpenCV Wiki, FaceDetection
The important functions in this example are cvLoad and cvHaarDetectObjects. The first one loads the classifier and the second one applies it to an image.
The standard classifiers work pretty well. Of course you can train your own classifiers, if the standard ones don't fit your purpose.
As you said there are a lot of algorithms for face detection. Some of them might provide better results, but OpenCV is definitively a good start.