LAB 10 – Modifying Pictures Using Loops (part 1 –Manipulating Pictures)

Lab Exercises

Topics

n To manipulate pictures

Exercises

4.2 Manipulating Pictures

Type in the following code in the Interactions window:

> String fileName;

> fileName = FileChooser.pickAFile();             // note that this pops up a window to select a jpg file

> Picture picture1;

> picture1 = new Picture(fileName);

> picture1.show();

>int width, height;

>width = picture1.getWidth();

>height = picture1.getHeight();

>System.out.println(“The pictures size is : ” + width + “ by “ + height);

//Get a pixel

>Pixel pixel1;

>pixel1 = picture1.getPixel (2,3);

>System.out.println(pixel1);

Try with different values for x and y.

//Get a row of pixels

>Pixel[] pixelArray;

>pixelArray = picture1.getPixels();        //notice the spelling of the method {is plural}

>System.out.println(pixelArray[5]);

//get the properties of a pixel

>System.out.println(pixel1.getX());

>System.out.println(pixel1.getY());

>System.out.println(pixel1.getColor());

>System.out.println(pixel1.getRed());

What was displayed?

You can also set the colors with

>pixel1.setRed(0);        //Note this removes the red for this pixel

You can also create new colors, but should first import the Color class

> import java.awt.Color;

>Color color1;

>color1 = new Color (0, 100, 0);         // light green

>System.out.println(color1);

>pixel1.setColor(color1);

>System.out.println(pixel1.getColor());

To see the changes, use repaint or show to redisplay the picture with the changes

>picture1.show();

You can adjust the colors by brightening or darkening the color:

>Color testColor;

>testColor = new Color(168, 131, 105);

>System.out.println(testColor);

>testColor = testColor.darker();

>System.out.println(testColor);

>testColor = testColor.brighter();

>System.out.println(testColor);

You can also pick a color:

> Color pickColor;

> pickColor = ColorChooser.pickAColor();

>System.out.println(pickColor);

You can write our modified picture to a file by typing:

>picture1.write(“newPicture.jpg”);

4.2.1 Exploring Pictures

Type in the following:

> import java.awt.Color;

> String fileName = "C:/intro-prog-java/mediasources/caterpillar.jpg";

> Picture pictureObj = new Picture(fileName);

> pictureObj.show();

> pictureObj.getPixel(10,100).setColor(Color.black);

> pictureObj.getPixel(11,100).setColor(Color.black);

> pictureObj.getPixel(12,100).setColor(Color.black);

> pictureObj.getPixel(13,100).setColor(Color.black);

> pictureObj.getPixel(14,100).setColor(Color.black);

> pictureObj.getPixel(15,100).setColor(Color.black);

> pictureObj.getPixel(16,100).setColor(Color.black);

> pictureObj.getPixel(17,100).setColor(Color.black);

> pictureObj.getPixel(18,100).setColor(Color.black);

> pictureObj.getPixel(19,100).setColor(Color.black);

> pictureObj.repaint();

> pictureObj.explore();