Realtime Data augmentation in Lasagne - machine-learning

I need to do realtime augmentation on my dataset for input to CNN, but i am having a really tough time finding suitable libraries for it. I have tried caffe but the DataTransform doesn't support many realtime augmentations like rotating etc. So for ease of implementation i settled with Lasagne. But it seems that it also doesn't support realtime augmentation. I have seen some posts related to Facial Keypoints detection where he's using Batchiterator of nolearn.lasagne. But i am not sure whether its realtime or not. There's no proper tutorial for it. So finally how should i do realtime augmentation in Lasagne either through nolearn or otherwise?

You can use Keras framework for real time data augmentation for CNN training. Here is the example code for CIFAR10 dataset from github. You can also change it to adapt your needs or copy source code and add to lasagne project but I have not tried importing to lasagne before. Basic idea behind this is randomly augmenting data in every batch. If you have for loop of batches that fits network, you can call your augmentation function before sending data to network.

Yes you can do real-time data augmentation in Lasagne. The simplest way is using the GaussianNoiseLayer. Simply insert it after your input layer. If Gaussian noise is not what you need, then at least you have GaussianNoiseLayer as an example for how to implement your own.
Note how the deterministic parameter is used in Lasagne. It is off by default, and so during training the noise is added. During testing you set deterministic=True and the augmentation is simply avoided.

Yes, the Facial Keypoints Recognition tutorial that you mention does use real-time (on the fly) augmentation to flip the input images (and target coordinates) at random.
The nolearn-utils library has a ton of examples of iterators that do several types of augmentation. E.g. AffineTransformBatchIteratorMixin does random affine transforms on the fly.

Related

What is the fastest way to use Tensorflow Object Detection API as a flat image recognizer?

I am new to computer vision but I am trying to code an android/ios app which does the following:
Get the live camera preview and try to detect one flat image (logo or painting) in that. In real-time. Draw a rect around the logo if found. If there is no match, dont draw the rectangle.
I found the Tensorflow Object Detection API as a good starting point. And support was just announced for importing TensorFlow models into Core ML.
I followed a lot of tutorials to train my own object detector. The training data is the key. I found a pretty good library to generate augmented image. I have created hundreds of variation of my image source (rotation, skew etc ...).
But it has failed! This dataset is probably good for image classification (with my image in full screen) but not in context (the room).
I think transfer-learning is the key, In my case, I used the ssd_mobilenet_v1_coco model as a base. I tried to fake the context of my augmented image with the Random Erasing Data Augmentation technique without success.
What are my available solutions? Do I tackle the problem rightly? I need to make the model training as fast as possible.
May I have to use some datasets for indoor-outdoor image classification and put my image randomly above? How important are the perspectives?
Thank you!
I have created hundreds of variation of my image source (rotation, skew etc ...). But it has failed!
So that mean your model did not converge or the final performance was bad? If your model did not converge then add more data. "Hundred of samples" is very few. So use more images and make more samples, and make your sample s dispersed as possible.
I think transfer-learning is the key, In my case, I used the ssd_mobilenet_v1_coco model as a base. I tried to fake the context of my augmented image with the Random Erasing Data Augmentation technique without success.
You mean fine-tuning. Did you reduced the label to 2 (your image and background) and did fine-tuning. If you didn't then you surely failed. Oh man, you should at least show me your model definition.
What are my available solutions? Do I tackle the problem rightly? I need to make the model training as fast as possible.
To make training converge faster, just add more GPUs and train on multiple GPUs. If you don't have money, rent some GPU cluster on Azure. Believe me, it is not that expensive.
Hope that help

It's possible to do object detection (one-class) in images retraining Inception model?

There is a way to do object detection, retraining Inception model provided by Google in Tensorflow? The goal is to predict wheter an image contains a defined category of objects (e.g. balls) or not. I can think about it as a one-class classification or multi-class with only two categories (ball and not-ball images). However, in the latter I think that it's very difficult to create a good training set (how many and which kind of not-ball images I need?).
Yes, there is a way to tell if something is a ball. However, it is better to use Google's Tensorflow Object Detection API for Tensorflow. Instead of saying "ball/no ball," it will tell you it thinks something is a ball with XX% accuracy.
To answer your other questions: with object detection, you don't need non-ball images for training. You should gather about 400-500 ball images (more is almost always better), split them into a training and an eval group, and label them with this. Then you should convert your labels and images into a .record file according to this. After that, you should set up Tensorflow and train.
This entire process is not easy. It took me a good couple of weeks with an iOS background to successfully train a single object detector. But it is worth it in the end, because now I can rapidly switch out images to train a different object detector whenever an app needs it.
Bonus: use this to convert your new TF model into a .mlmodel usable by iOS/Android.

Face recognition with a small number of samples

Can anyone advise me way to build effective face classifier that may be able to classify many different faces (~1000)?
And i have only 1-5 examples of each face
I know about opencv face classifier, but it works bad for my task (many classes, a few samples).
It works alright for one face classification with small number of samples. But i think that 1k separate classifier is not good idea
I read a few articles about face recognition but methods from these articles reqiues a lot of samples of each class for work
PS Sorry for my writing mistakes. English in not my native language.
Actually, for giving you a proper answer, I'd be happy to know some details of your task and your data. Face Recognition is a non-trivial problem and there is no general solution for all sorts of image acquisition.
First of all, you should define how many sources of variation (posing, emotions, illumination, occlusions or time-lapse) you have in your sample and testing sets. Then you should choose an appropriate algorithm and, very importantly, preprocessing steps according to the types.
If you don't have any significant variations, then it is a good idea to consider for a small training set one of the Discrete Orthogonal Moments as a feature extraction method. They have a very strong ability to extract features without redundancy. Some of them (Hahn, Racah moments) can also work in two modes - local and global feature extraction. The topic is relatively new, and there are still few articles about it. Although, they are thought to become a very powerful tool in Image Recognition. They can be computed in near real-time by using recurrence relationships. For more information, have a look here and here.
If the pose of the individuals significantly varies, you may try to perform firstly pose correction by Active Appearance Model.
If there are lots of occlusions (glasses, hats) then using one of the local feature extractors may help.
If there is a significant time lapse between train and probe images, the local features of the faces could change over the age, then it's a good option to try one of the algorithms which use graphs for face representation so as to keep the face topology.
I believe that non of the above are implemented in OpenCV, but for some of them you can find MATLAB implementation.
I'm not native speaker as well, so sorry for the grammar
Coming to your problem , it is very unique in its way. As you said there are only few images per class , the model which we train should either have an awesome architecture which can create better features within an image itself , or there should be an different approach which can achieve this task .
I have four things which I can share as of now :
Do data pre-processing and then create a bigger dataset and train on a neural network ideally. Here, we can do pre-processing like:
- image rotation
- image shearing
- image scaling
- image blurring
- image stretching
- image translation
and create atleast 200 images per class. Please checkout opencv documentation which provides many more methods on how you can increase the size of your dataset. Once you do this, then we can apply transfer learning , which is a better approach than training a neural network from scratch.
Transfer learning is a method where we train a network on our own custom classes , and this network is already pre-trained on 1000's of classes. Since our data here is very less, I would prefer transfer learning only. I have written a blog on how you can approach this using tranfer learning after you have the required amount of data. It is linked here. Face recognition also is a classification task itself, where each human is a separate class. So, follow the instructions given in the blog , may be it would help you create your own powerful classifer.
Another suggestion would be , after creating a dataset , encode them properly. This encoding would help you preserve the features in an image and can help you train better networks. VLAD ,Fisher , Bag of Words are few encoding techniques. You can search few repositories online which have implemented these already on ORL database. Once you encode , train the network on the encodings , you will obviously see a better performance.
Even do check out , Siamese network here which is meant for this purpose I feel . Here they compare two images with similar characteristics on different networks and there by achieve better classification accuracies . Git repository is here.
Another standard approach would be using SVM , Random forests since the data is less. If you still prefer neural networks the above methods would serve you the purpose. If you intend to go with encodings , then I would suggest random forests , as it is highly preferrable in learning and flexible too.
Hopefully , this answer would help you proceed in the right direction of achieving things.
You might want to take a look at OpenFace, a Python and Torch implementantion of face recognition with deep neural networks: https://cmusatyalab.github.io/openface/

Image classification/recognition open source library

I have a set of reference images (200) and a set of photos of those images (tens of thousands). I have to classify each photo in a semi-automated way. Which algorithm and open source library would you advise me to use for this task? The best thing for me would be to have a similarity measure between the photo and the reference images, so that I would show to a human operator the images ordered from the most similar to the least one, to make her work easier.
To give a little more context, the reference images are branded packages, and the photos are of the same packages, but with all kinds of noises: reflections from the flash, low light, imperfect perspective, etc. The photos are already (manually) segmented: only the package is visible.
Back in my days with image recognition (like 15 years ago) I would have probably tried to train a neural network with the reference images, but I wonder if now there are better ways to do this.
I recommend that you use Python, and use the NumPy/SciPy libraries for your numerical work. Some helpful libraries for handling images are the Mahotas library and the scikits.image library.
In addition, you will want to use scikits.learn, which is a Python wrapper for Libsvm, a very standard SVM implementation.
The hard part is choosing your descriptor. The descriptor will be the feature you compute from each image, intended to compute a similarity distance with the set of reference images. A good set of things to try would be Histogram of Oriented Gradients, SIFT features, and color histograms, and play around with various ways of binning the different parts of the image and concatenating such descriptors together.
Next, set aside some of your data for training. For these data, you have to manually label them according to the true reference image they belong to. You can feed these labels into built-in functions in scikits.learn and it can train a multiclass SVM to recognize your images.
After that, you may want to look at MPI4Py, an implementation of MPI in Python, to take advantage of multiprocessors when doing the large descriptor computation and classification of the tens of thousands of remaining images.
The task you describe is very difficult and solving it with high accuracy could easily lead to a research-level publication in the field of computer vision. I hope I've given you some starting points: searching any of the above concepts on Google will hit on useful research papers and more details about how to use the various libraries.
The best thing for me would be to have a similarity measure between the photo and the reference images, so that I would show to a human operator the images ordered from the most similar to the least one, to make her work easier.
One way people do this is with the so-called "Earth mover's distance". Briefly, one imagines each pixel in an image as a stack of rocks with height corresponding to the pixel value and defines the distance between two images as the minimal amount of work needed to transfer one arrangement of rocks into the other.
Algorithms for this are a current research topic. Here's some matlab for one: http://www.cs.huji.ac.il/~ofirpele/FastEMD/code/ . Looks like they have a java version as well. Here's a link to the original paper and C code: http://ai.stanford.edu/~rubner/emd/default.htm
Try Radpiminer (one of the most widely used data-mining platform, http://rapid-i.com) with IMMI (Image Mining Extension, http://www.burgsys.com/mumi-image-mining-community.php), AGPL licence.
It currently implements several similarity measurement methods (not only trivial pixel by pixel comparison). The similarity measures can be input for a learning algorithm (e.g. neural network, KNN, SVM, ...) and it can be trained in order to give better performance. Some information bout the methods is given in this paper:
http://splab.cz/wp-content/uploads/2012/07/artery_detection.pdf
Now-a-days Deep Learning based framworks like Torch , Tensorflow, Theano, Keras are the best open source tool/library for object classification/recognition tasks.

machine learning - svm feature fusion techique

for my final thesis i am trying to build up an 3d face recognition system by combining color and depth information. the first step i did, is to realign the data-head to an given model-head using the iterative closest point algorithm. for the detection step i was thinking about using the libsvm. but i dont understand how to combine the depth and the color information to one feature vector? they are dependent information (each point consist of color (RGB), depth information and also scan quality).. what do you suggest to do? something like weighting?
edit:
last night i read an article about SURF/SIFT features i would like to use them! could it work? the concept would be the following: extracting this features out of the color image and the depth image (range image), using each feature as a single feature vector for the svm?
Concatenation is indeed a possibility. However, as you are working on 3d face recognition you should have some strategy as to how you go about it. Rotation and translation of faces will be hard to recognize using a "straightforward" approach.
You should decide whether you attempt to perform a detection of the face as a whole, or of sub-features. You could attempt to detect rotation by finding some core features (eyes, nose, etc).
Also, remember that SVMs are inherently binary (i.e. they separate between two classes). Depending on your exact application you will very likely have to employ some multi-class strategy (One-against-all or One-against-many).
I would recommend doing some literature research to see how others have attacked the problem (a google search will be a good start).
It sounds simple, but you can simply concatenate the two vectors into one. Many researchers do this.
What you arrived at is an important open problem. Yes, there are some ways to handle it, as mentioned here by Eamorr. For example you can concatenate and do PCA (or some non linear dimensionality reduction method). But it is kind of hard to defend the practicality of doing so, considering that PCA takes O(n^3) time in the number of features. This alone might be unreasonable for data in vision that may have thousands of features.
As mentioned by others, the easiest approach is to simply combine the two sets of features into one.
SVM is characterized by the normal to the maximum-margin hyperplane, where its components specify the weights/importance of the features, such that higher absolute values have a larger impact on the decision function. Thus SVM assigns weights to each feature all on its own.
In order for this to work, obviously you would have to normalize all the attributes to have the same scale (say transform all features to be in the range [-1,1] or [0,1])

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