Creating your own image data files

1. Creating your own image data files

2. Simple ASCII file output in Java import java.io.FileOutputStream; import java.io.PrintWriter; … PrintWriter out = null; try { out = new PrintWriter( new FileOutputStream("fred.txt") ); } catch (Exception e) { System.err.println( "error: " + e ); return; } out.println( "hello" ); … out.close();

3. P2 = ASCII grey PGM • Each pixel has one integer (grey) value. P2 w h maxval v1 v2 v3 … . . . . . . . . . vw*h

4. P3 = ASCII color PPM • Each pixel’s color is represented as three consecutive values, <red,green,blue>. P3 w h maxval v1r v1g v1b v2r v2g v2b . . . . . . . . . vw*hr vw*hg vw*hb

5. Exercise Write a simple program that creates an image of the sin function. • file format: pgm (P2 / grey) • file name: out.pgm • Don’t use code other than your own.

6. Exercise Write a simple program that creates an image of the sin function. • sin function: • width/domain/x: [0..2Pi] • y: real numbers [-1.0..+1.0] • image: • width: 500 pixels ({0,..,499}) • height: 250 pixels (repeat values from sin 250 times) • pixel values: integers {0,…,255}

7. Exercise (cont’d.) Part A. • Download GIMP (gimp.org), and load your PGM file into GIMP. • Email your code (including doxygen/javadoc comments) that produced the image data file to me. • The email subject must be: CV sin A assignment. Same values across each line repeated over and over and over for every line.

8. Transfer files to and from the Android and PCs • When you connect the Android to a PC, it will mount the Android file system on the PC. • From the PC, click on Computer. Then click on the Android (mounted as Portable Media Player). Then click on Tablet. Then click on Download. • Copy images to and from the Android’s Download folder. • On the Android, Apps --> My Files. Then navigate to /storage/sdcard0/Download. • These are the same Download folder.

9. Exercise (cont’d.) Part B. • Download and build Albie. • Copy your pgm file from PC to Albie Download folder. • Run Albie. (Note: Loading this ASCII file on a Samsung Galaxy Tab 3 takes 30 seconds.) • Use Albie’s Save option, and email the resulting JPEG to me. • The email subject must be: CV sin B assignment. Same values across each line repeated over and over and over for every line.