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diff --git a/tensorflow/contrib/lite/g3doc/tfmobile/index.md b/tensorflow/contrib/lite/g3doc/tfmobile/index.md new file mode 100644 index 0000000000..bd047bfcec --- /dev/null +++ b/tensorflow/contrib/lite/g3doc/tfmobile/index.md @@ -0,0 +1,284 @@ +book_path: /mobile/_book.yaml +project_path: /mobile/_project.yaml + +# Overview + +TensorFlow was designed to be a good deep learning solution for mobile +platforms. Currently we have two solutions for deploying machine learning +applications on mobile and embedded devices: TensorFlow for Mobile and +<a href="../index.md">TensorFlow Lite</a>. + +## TensorFlow Lite versus TensorFlow Mobile + +Here are a few of the differences between the two: + +- TensorFlow Lite is an evolution of TensorFlow Mobile. In most cases, apps + developed with TensorFlow Lite will have a smaller binary size, fewer + dependencies, and better performance. + +- TensorFlow Lite is in developer preview, so not all use cases are covered yet. + We expect you to use TensorFlow Mobile to cover production cases. + +- TensorFlow Lite supports only a limited set of operators, so not all models + will work on it by default. TensorFlow for Mobile has a fuller set of + supported functionality. + +TensorFlow Lite provides better performance and a small binary size on mobile +platforms as well as the ability to leverage hardware acceleration if available +on their platforms. In addition, it has many fewer dependencies so it can be +built and hosted on simpler, more constrained device scenarios. TensorFlow Lite +also allows targeting accelerators through the [Neural Networks +API](https://developer.android.com/ndk/guides/neuralnetworks/index.html). + +TensorFlow Lite currently has coverage for a limited set of operators. While +TensorFlow for Mobile supports only a constrained set of ops by default, in +principle if you use an arbitrary operator in TensorFlow, it can be customized +to build that kernel. Thus use cases which are not currently supported by +TensorFlow Lite should continue to use TensorFlow for Mobile. As TensorFlow Lite +evolves, it will gain additional operators, and the decision will be easier to +make. + + +## Introduction to TensorFlow Mobile + +TensorFlow was designed from the ground up to be a good deep learning solution +for mobile platforms like Android and iOS. This mobile guide should help you +understand how machine learning can work on mobile platforms and how to +integrate TensorFlow into your mobile apps effectively and efficiently. + +## About this Guide + +This guide is aimed at developers who have a TensorFlow model that’s +successfully working in a desktop environment, who want to integrate it into +a mobile application, and cannot use TensorFlow Lite. Here are the +main challenges you’ll face during that process: + +- Understanding how to use Tensorflow for mobile. +- Building TensorFlow for your platform. +- Integrating the TensorFlow library into your application. +- Preparing your model file for mobile deployment. +- Optimizing for latency, RAM usage, model file size, and binary size. + +## Common use cases for mobile machine learning + +**Why run TensorFlow on mobile?** + +Traditionally, deep learning has been associated with data centers and giant +clusters of high-powered GPU machines. However, it can be very expensive and +time-consuming to send all of the data a device has access to across a network +connection. Running on mobile makes it possible to deliver very interactive +applications in a way that’s not possible when you have to wait for a network +round trip. + +Here are some common use cases for on-device deep learning: + +### Speech Recognition + +There are a lot of interesting applications that can be built with a +speech-driven interface, and many of these require on-device processing. Most of +the time a user isn’t giving commands, and so streaming audio continuously to a +remote server would be a waste of bandwidth, since it would mostly be silence or +background noises. To solve this problem it’s common to have a small neural +network running on-device +[listening out for a particular keyword](../tutorials/sequences/audio_recognition). +Once that keyword has been spotted, the rest of the +conversation can be transmitted over to the server for further processing if +more computing power is needed. + +### Image Recognition + +It can be very useful for a mobile app to be able to make sense of a camera +image. If your users are taking photos, recognizing what’s in them can help your +camera apps apply appropriate filters, or label the photos so they’re easily +findable. It’s important for embedded applications too, since you can use image +sensors to detect all sorts of interesting conditions, whether it’s spotting +endangered animals in the wild +or +[reporting how late your train is running](https://svds.com/tensorflow-image-recognition-raspberry-pi/). + +TensorFlow comes with several examples of recognizing the types of objects +inside images along with a variety of different pre-trained models, and they can +all be run on mobile devices. You can try out +our +[Tensorflow for Poets](https://codelabs.developers.google.com/codelabs/tensorflow-for-poets/index.html#0) and +[Tensorflow for Poets 2: Optimize for Mobile](https://codelabs.developers.google.com/codelabs/tensorflow-for-poets-2/index.html#0) codelabs to +see how to take a pretrained model and run some very fast and lightweight +training to teach it to recognize specific objects, and then optimize it to +run on mobile. + +### Object Localization + +Sometimes it’s important to know where objects are in an image as well as what +they are. There are lots of augmented reality use cases that could benefit a +mobile app, such as guiding users to the right component when offering them +help fixing their wireless network or providing informative overlays on top of +landscape features. Embedded applications often need to count objects that are +passing by them, whether it’s pests in a field of crops, or people, cars and +bikes going past a street lamp. + +TensorFlow offers a pretrained model for drawing bounding boxes around people +detected in images, together with tracking code to follow them over time. The +tracking is especially important for applications where you’re trying to count +how many objects are present over time, since it gives you a good idea when a +new object enters or leaves the scene. We have some sample code for this +available for Android [on +GitHub](https://github.com/tensorflow/tensorflow/tree/master/tensorflow/examples/android), +and also a [more general object detection +model](https://github.com/tensorflow/models/tree/master/research/object_detection/README.md) +available as well. + +### Gesture Recognition + +It can be useful to be able to control applications with hand or other +gestures, either recognized from images or through analyzing accelerometer +sensor data. Creating those models is beyond the scope of this guide, but +TensorFlow is an effective way of deploying them. + +### Optical Character Recognition + +Google Translate’s live camera view is a great example of how effective +interactive on-device detection of text can be. + +<div class="video-wrapper"> + <iframe class="devsite-embedded-youtube-video" data-video-id="06olHmcJjS0" + data-autohide="1" data-showinfo="0" frameborder="0" allowfullscreen> + </iframe> +</div> + +There are multiple steps involved in recognizing text in images. You first have +to identify the areas where the text is present, which is a variation on the +object localization problem, and can be solved with similar techniques. Once you +have an area of text, you then need to interpret it as letters, and then use a +language model to help guess what words they represent. The simplest way to +estimate what letters are present is to segment the line of text into individual +letters, and then apply a simple neural network to the bounding box of each. You +can get good results with the kind of models used for MNIST, which you can find +in TensorFlow’s tutorials, though you may want a higher-resolution input. A +more advanced alternative is to use an LSTM model to process a whole line of +text at once, with the model itself handling the segmentation into different +characters. + +### Translation + +Translating from one language to another quickly and accurately, even if you +don’t have a network connection, is an important use case. Deep networks are +very effective at this sort of task, and you can find descriptions of a lot of +different models in the literature. Often these are sequence-to-sequence +recurrent models where you’re able to run a single graph to do the whole +translation, without needing to run separate parsing stages. + +### Text Classification + +If you want to suggest relevant prompts to users based on what they’re typing or +reading, it can be very useful to understand the meaning of the text. This is +where text classification comes in. Text classification is an umbrella term +that covers everything from sentiment analysis to topic discovery. You’re likely +to have your own categories or labels that you want to apply, so the best place +to start is with an example +like +[Skip-Thoughts](https://github.com/tensorflow/models/tree/master/research/skip_thoughts/), +and then train on your own examples. + +### Voice Synthesis + +A synthesized voice can be a great way of giving users feedback or aiding +accessibility, and recent advances such as +[WaveNet](https://deepmind.com/blog/wavenet-generative-model-raw-audio/) show +that deep learning can offer very natural-sounding speech. + +## Mobile machine learning and the cloud + +These examples of use cases give an idea of how on-device networks can +complement cloud services. Cloud has a great deal of computing power in a +controlled environment, but running on devices can offer higher interactivity. +In situations where the cloud is unavailable, or your cloud capacity is limited, +you can provide an offline experience, or reduce cloud workload by processing +easy cases on device. + +Doing on-device computation can also signal when it's time to switch to working +on the cloud. A good example of this is hotword detection in speech. Since +devices are able to constantly listen out for the keywords, this then triggers a +lot of traffic to cloud-based speech recognition once one is recognized. Without +the on-device component, the whole application wouldn’t be feasible, and this +pattern exists across several other applications as well. Recognizing that some +sensor input is interesting enough for further processing makes a lot of +interesting products possible. + +## What hardware and software should you have? + +TensorFlow runs on Ubuntu Linux, Windows 10, and OS X. For a list of all +supported operating systems and instructions to install TensorFlow, see +<a href="https://www.tensorflow.org/install">Installing Tensorflow</a>. + +Note that some of the sample code we provide for mobile TensorFlow requires you +to compile TensorFlow from source, so you’ll need more than just `pip install` +to work through all the sample code. + +To try out the mobile examples, you’ll need a device set up for development, +using +either [Android Studio](https://developer.android.com/studio/install.html), +or [XCode](https://developer.apple.com/xcode/) if you're developing for iOS. + +## What should you do before you get started? + +Before thinking about how to get your solution on mobile: + +1. Determine whether your problem is solvable by mobile machine learning +2. Create a labelled dataset to define your problem +3. Pick an effective model for the problem + +We'll discuss these in more detail below. + +### Is your problem solvable by mobile machine learning? + +Once you have an idea of the problem you want to solve, you need to make a plan +of how to build your solution. The most important first step is making sure that +your problem is actually solvable, and the best way to do that is to mock it up +using humans in the loop. + +For example, if you want to drive a robot toy car using voice commands, try +recording some audio from the device and listen back to it to see if you can +make sense of what’s being said. Often you’ll find there are problems in the +capture process, such as the motor drowning out speech or not being able to hear +at a distance, and you should tackle these problems before investing in the +modeling process. + +Another example would be giving photos taken from your app to people see if they +can classify what’s in them, in the way you’re looking for. If they can’t do +that (for example, trying to estimate calories in food from photos may be +impossible because all white soups look the same), then you’ll need to redesign +your experience to cope with that. A good rule of thumb is that if a human can’t +handle the task then it will be difficult to train a computer to do better. + +### Create a labelled dataset + +After you’ve solved any fundamental issues with your use case, you need to +create a labeled dataset to define what problem you’re trying to solve. This +step is extremely important, more than picking which model to use. You want it +to be as representative as possible of your actual use case, since the model +will only be effective at the task you teach it. It’s also worth investing in +tools to make labeling the data as efficient and accurate as possible. For +example, if you’re able to switch from having to click a button on a web +interface to simple keyboard shortcuts, you may be able to speed up the +generation process a lot. You should also start by doing the initial labeling +yourself, so you can learn about the difficulties and likely errors, and +possibly change your labeling or data capture process to avoid them. Once you +and your team are able to consistently label examples (that is once you +generally agree on the same labels for most examples), you can then try and +capture your knowledge in a manual and teach external raters how to run the same +process. + +### Pick an effective model + +The next step is to pick an effective model to use. You might be able to avoid +training a model from scratch if someone else has already implemented a model +similar to what you need; we have a repository of models implemented in +TensorFlow [on GitHub](https://github.com/tensorflow/models) that you can look +through. Lean towards the simplest model you can find, and try to get started as +soon as you have even a small amount of labelled data, since you’ll get the best +results when you’re able to iterate quickly. The shorter the time it takes to +try training a model and running it in its real application, the better overall +results you’ll see. It’s common for an algorithm to get great training accuracy +numbers but then fail to be useful within a real application because there’s a +mismatch between the dataset and real usage. Prototype end-to-end usage as soon +as possible to create a consistent user experience. |