I cropped the following image from a tutorial.
this diagram shows a rough structure of a standard neural network. takes one image as input and make a prediction.
what I am thinking about is some kind of parallel structure. think about something like the following image.
not exactly as in the above image. But you can see I am trying to use two images to make one prediction. this image is for you to get an idea about what I am trying to ask.
is it possible to use more than one (two, three ..) images like this or any other way in order to make one prediction. now, this is not to be used in actual photo classification. But I think such a technique can be used in a file like audio classification where a graphical representation of data is used with image classification techniques.
any advice, guidance or opinion on this?
if we consider implementing exactly what is in the diagram, if I use a high-level API like Keras (Keras.model.sequential) all we can do is keep adding a layer one after the other.
so what kind of technology can I use to implement the parallel structure
Yes, you can use more than one image as input. See for example the Siamese Neural Network which takes as input 2 images and passes them through a shared network architecture.
If instead you want to have an arbitrary and variable number of images as input you can use an architecture based on Recurrent Neural Networks like Convolutional LSTM, which essentially applies a CNN to every image of the input sequence using an LSTM recurrent network.
Related
I have data-set regarding chocolates. I need to detect whether it has scratches or not. I am planning to detect from Convolution Neural Network using Caffe. But how to define which neural network architecture will suit to my data-set?
Also how to generate heat values when there is any scratches in image?
I have tried detect normal image processing algorithms and it did not work.
Abnormal Image
Normal Image
Based on the little info you provide, the network architecture choice should be the last of your concerns. Also "trying normal image processing algorithms" is quite a vague statement.
A few points to consider
How big is the dataset? Are the chocolate photos taken in a controlled setting where they are always similar to your example photos or are they taken in the wild, i.e. where they could have different lighting conditions, positions, etc.? Is the dataset balanced?
How is the dataset labelled? Is it just a class for the whole image specifying normal vs abnormal? If so, you'd just be doing classification, and one way to potentially just visualise the location of the scratches (if they turn out to be the most prominent feature for the classification) is to use gradient-weighted class activation maps. On the other hand, if your dataset has labelled scratch points over images, then you can directly train your network to output heatmaps.
Once your dataset is properly set up with a training and validation set, you can just start with a baseline simple small convolutional network architecture, and then you can try out different and bigger network architectures like VGG16, ResNet, etc., and check whether they improve performance on your validation set.
I'm not looking for a chunk of code as a solution, just the name of the model I'd need to implement or some links would be nice.
My problem is I have a dataset I've made of a few hundred 128x128 images (abstract paintings) - I'd like to simply generate more images similar to these images using a neural network (preferably no input needed for the network, except maybe random values?), but it's unclear as to how I'd go about this.
One solution I've thought about but haven't tried out yet is making an LSTM neural network, turning the paintings into 1D arrays of pixel values, and feeding the arrays to the network (LSTM networks are real good at learning sequences) - but if I'd want to work with larger images, this might not be very practical.
Any info is greatly appreciated. Thanks!
GANs (generative adversarial networks) would be appropriate in this case. GANs rely on two separate neural networks and, when properly trained, can be used to generate new images (a process known as hallucinating) that are similar to a collection of known images.
there are many examples of using GANs to generate new images of numbers from the canonical mnist dataset. naturally, you can replace mnist with your abstract paintings.
I want to use pre-trained model for the face identification. I try to use Siamese architecture which requires a few number of images. Could you give me any trained model which I can change for the Siamese architecture? How can I change the network model which I can put two images to find their similarities (I do not want to create image based on the tutorial here)? I only want to use the system for real time application. Do you have any recommendations?
I suppose you can use this model, described in Xiang Wu, Ran He, Zhenan Sun, Tieniu Tan A Light CNN for Deep Face Representation with Noisy Labels (arXiv 2015) as a a strating point for your experiments.
As for the Siamese network, what you are trying to earn is a mapping from a face image into some high dimensional vector space, in which distances between points reflects (dis)similarity between faces.
To do so, you only need one network that gets a face as an input and produce a high-dim vector as an output.
However, to train this single network using the Siamese approach, you are going to duplicate it: creating two instances of the same net (you need to explicitly link the weights of the two copies). During training you are going to provide pairs of faces to the nets: one to each copy, then the single loss layer on top of the two copies can compare the high-dimensional vectors representing the two faces and compute a loss according to a "same/not same" label associated with this pair.
Hence, you only need the duplication for the training. In test time ('deploy') you are going to have a single net providing you with a semantically meaningful high dimensional representation of faces.
For a more advance Siamese architecture and loss see this thread.
On the other hand, you might want to consider the approach described in Oren Tadmor, Yonatan Wexler, Tal Rosenwein, Shai Shalev-Shwartz, Amnon Shashua Learning a Metric Embedding for Face Recognition using the Multibatch Method (arXiv 2016). This approach is more efficient and easy to implement than pair-wise losses over image pairs.
I have some questions about how to actually interact with a pre-trained Caffe model. In my case I'm using a model for scene recognition.
In the caffe git repository, there are some code examples in Python and C++ on the implementations of Image Classifiers. However, those do not apply to my use case (since they only classify the input image as ONE class).
My goal is an application that takes an input image (jpg) and outputs the highest predicted class label for each pixel in the input image (e.i., indices for sky, beach, road, car).
Could anyone give me some pointers on how to proceed?
There already seem to exist implementations for this. This demo (http://places.csail.mit.edu/demo.html) is kind of what I what.
Thank you!
What you are looking for is not image classification, but rather semantic segmentation.
A recent work, by Jonathan Long, Evan Shelhamer and Trevor Darrell is based on Caffe, and can be found here. It uses fully convolutional network, that is, a network with no "InnerProduct" layers only convolutional layers, thus capable of producing outputs with different sizes for different sizes of inputs.
If I've understood correctly, when training neural networks to recognize objects in images it's common to map single pixel to a single input layer node. However, sometimes we might have a large picture with only a small area of interest. For example, if we're training a neural net to recognize traffic signs, we might have images where the traffic sign covers only a small portion of it, while the rest is taken by the road, trees, sky etc. Creating a neural net which tries to find a traffic sign from every position seems extremely expensive.
My question is, are there any specific strategies to handle these sort of situations with neural networks, apart from preprocessing the image?
Thanks.
Using 1 pixel per input node is usually not done. What enters your network is the feature vector and as such you should input actual features, not raw data. Inputing raw data (with all its noise) will not only lead to bad classification but training will take longer than necessary.
In short: preprocessing is unavoidable. You need a more abstract representation of your data. There are hundreds of ways to deal with the problem you're asking. Let me give you some popular approaches.
1) Image proccessing to find regions of interest. When detecting traffic signs a common strategy is to use edge detection (i.e. convolution with some filter), apply some heuristics, use a threshold filter and isolate regions of interest (blobs, strongly connected components etc) which are taken as input to the network.
2) Applying features without any prior knowledge or image processing. Viola/Jones use a specific image representation, from which they can compute features in a very fast way. Their framework has been shown to work in real-time. (I know their original work doesn't state NNs but I applied their features to Multilayer Perceptrons in my thesis, so you can use it with any classifier, really.)
3) Deep Learning.
Learning better representations of the data can be incorporated into the neural network itself. These approaches are amongst the most popular researched atm. Since this is a very large topic, I can only give you some keywords so that you can research it on your own. Autoencoders are networks that learn efficient representations. It is possible to use them with conventional ANNs. Convolutional Neural Networks seem a bit sophisticated at first sight but they are worth checking out. Before the actual classification of a neural network, they have alternating layers of subwindow convolution (edge detection) and resampling. CNNs are currently able to achieve some of the best results in OCR.
In every scenario you have to ask yourself: Am I 1) giving my ANN a representation that has all the data it needs to do the job (a representation that is not too abstract) and 2) keeping too much noise away (and thus staying abstract enough).
We usually dont use fully connected network to deal with image because the number of units in the input layer will be huge. In neural network, we have specific neural network to deal with image which is Convolutional neural network(CNN).
However, CNN plays a role of feature extractor. The encoded feature will finally feed into a fully connected network which act as a classifier. In your case, I dont know how small your object is compare to the full image. But if the interested object is really small, even use CNN, the performance for image classification wont be very good. Then we probably need to use object detection(which used sliding window) to deal with it.
If you want recognize small objects on large sized image, you should use "scanning window".
For "scanning window" you can to apply dimention reducing methods:
DCT (http://en.wikipedia.org/wiki/Discrete_cosine_transform)
PCA (http://en.wikipedia.org/wiki/Principal_component_analysis)