Android Part 1 April 13

Bernd Girod, David Chen: EE368 Mobile Image Processing – Part 1 no. 1

Mobile image processing – Part 1

Mobile application development on Android Project 1: “Hello Image”, reading/writing/modifying images Project 2: “Viewfinder EE368”, processing viewfinder frames Project 3: “CVCamera”, utilizing OpenCV functions Mobile application examples


http://www.stanford.edu/~gtakacs/publication.html

Mobile landmark recognition


http://www.stanford.edu/~sstsai/research.html

Mobile product recognition


Popular mobile platforms

Symbian

Apple iOS

Windows 7

Nokia N8 HTC Arrive Samsung Focus

iPhone iPad Motorola Droid

Nokia N97

Android

Samsung Galaxy Tab


Spotlight on Android

Open source mobile platform developed by Google Supported by Open Handset Alliance

13 mobile operators 18 handset manufacturers 20 semiconductor companies 16 software makers

Uses an open-source, customizable Linux kernel and a virtual machine designed for mobile hardware

Largest share of smartphone market in the US Android Market now contains over 250k apps


Android software stack

[ Professional Android Application Development ]

Linux Kernel


Programming in Java

Android encourages high-level development Android uses Java as the main programming language Inherits basic classes from conventional Java

String, Container, Math, IO, Network

Adds new classes specific to mobile devices Camera, Telephony, Map, GPS, Speech


Android programming with Eclipse

EclipseIDE

AndroidSDK

JavaRuntime

program installation and execution

system messages

programmer inputs

data and messages Internet


Class tutorials for Android (1)

Android tutorials designed specifically for mobile image processing in the EE368 class

Tutorial #1: Basic Android Setup Image processing-oriented introduction to Android Explains how to download and install the different software

packages (JDK, SDK, Eclipse) on your own computer Shows how to build and run a viewfinder app that computes color

histograms in real time

Tutorial #2: OpenCV for Android Setup Builds on core skills developed in Tutorial #1 Explains how to download and install OpenCV for Android Shows how to build a more advanced viewfinder app that computes

various image feature keypoints supported by OpenCV


Class tutorials for Android (2)

http://ee368.stanford.edu/Android

Support for Windows, Macintosh, and Linux in both tutorials


Eclipse IDE

Project files

Class hierarchy

Text editor

Errors and warnings

Different perspectives


Structure of an Android Project in Eclipse

Programmer-defined Java filesProgram new functions here

Auto-generated Java filesDon’t edit anything here

Android libraryDon’t edit anything here

Resource filesEdit layout, define constants,

import external media files, change program permissions

Java Native Interface filesC/C++ code


“Hello Image” project

Goals of this project Learn how to create a new Android project Learn how to read/write images from/to SD card Learn how to access and modify image bitmaps

Full source available on class website: http://ee368.stanford.edu/Android/HelloImage


Recommended project settings (1)


Recommended project settings (2)


HelloImage Activity class (1)

public class HelloImage extends Activity {Bitmap myBitmap;ImageView myImageView;

public void onCreate(Bundle savedInstanceState) { … }

private void processImage() { … }

private void brighten(int offset) { … }}

Subclass of Activity class will be visible on the phone


public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);

String imageFileName = “/sdcard/test_vga.jpg”;File imageFile = new File(imageFileName);if (imageFile.exists()) {

// Load the image from filemyBitmap = BitmapFactory.decodeFile(imageFileName);

// Display the image in the image viewermyImageView = (ImageView)findViewById(R.id.my_image_view);if (myImageView != null) {

myImageView.setImageBitmap(myBitmap);}

}}


onCreate called when the application first starts

Load image from SD card

Display image in viewer


private void processImage() {brighten(50);

try {String outputPath = "/sdcard/test_vga_output.jpg";int quality = 75;FileOutputStream fileOutStr = new FileOutputStream(outputPath);BufferedOutputStream bufOutStr =

new BufferedOutputStream(fileOutStr);myBitmap.compress(CompressFormat.JPEG, quality, bufOutStr);bufOutStr.flush(); bufOutStr.close();

} catch (FileNotFoundException exception) { Log.e("debug_log", exception.toString());

} catch (IOException exception) {Log.e("debug_log", exception.toString());

}

myImageView.setImageBitmap(myBitmap);}


Apply some image processing operation on the stored bitmap

Save the processed image to the SD card

Catch exceptions

Show the image on the display


private void brighten(int brightenOffset) {// Create new arrayint width = myBitmap.getWidth(); int height = myBitmap.getHeight();int[] pix = new int[width * height];myBitmap.getPixels(pix, 0, width, 0, 0, width, height);

// Apply pixel-by-pixel changeint index = 0;for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) {

int r = (pix[index] >> 16) & 0xff;int g = (pix[index] >> 8) & 0xff;int b = pix[index] & 0xff;r = Math.max(0, Math.min(255, r + brightenOffset));g = Math.max(0, Math.min(255, g + brightenOffset));b = Math.max(0, Math.min(255, b + brightenOffset));pix[index++] = 0xff000000 | (r << 16) | (g << 8) | b;

} // x } // y

// Change bitmap to use new arraymyBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);myBitmap.setPixels(pix, 0, width, 0, 0, width, height);

}


Extract RGB Values

Pack RGB Values


Running the program on an Android device

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“Hello Image” application running on device

http://ee368.stanford.edu/Android/HelloImage


Class Project: Plant Leaf Classification

D. Knight, J. Painter, and M. Potter, Spring 2010http://ee368.stanford.edu/Project_10


Class Project: Jigsaw Puzzle Solver

L. Liang and Z. Liu, Spring 2010http://ee368.stanford.edu/Project_10


Mobile image processing – Part 1

Mobile application development on Android Project 1: “Hello Image”, reading/writing/modifying images Project 2: “Viewfinder EE368”, processing viewfinder frames Project 3: “CVCamera”, utilizing OpenCV functions Mobile application examples

Android Part 1 April 13

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Transcript of Android Part 1 April 13