1. Nested Loops Circles inside Circles
Picture Two
Nested Loops
Circles inside Circles

2. Lab Review - Problem Extract the red plane of an image.
Display the original image
Display the red plane only of the image
Both should be displayed simulataeously

3. Lab Review - Problem Analysis
orig
setVisible()
getRedPlane()
Instantiates
Picture Class
Returned from
redPlaneImg
setVisible()

4. Lab Review – The Procedure
public Picture getRedPlane() {
// get the pixels of this picture
Pixel [] origPixData = this.getPixels();
// make a blank picture of the same size
Picture newPict = new Picture(this.getWidth(), this.getHeight());
// get the pixels of the new picture
Pixel [] newPixData = newPict.getPixels();
// Set the new picture's pixels to the red value in this picture
// For you to supply
return newPict; }

5. Another Problem
Rotate the picture clockwise by 90 and return the rotated image as a new Picture Image?

6. Java Hint We can treat an image as a 2-D object using nested loops!
for(int col = 0; col < this.getWidth(); col++ {
for(int row = 0; row < this.getHeight(); row++) {
Pixel pix = this.getPixel(col,row);
// do something with pix }

7. Analysis 1 2 3 4 5 6 7 8 9 10 11 Rotate Clockwise (0,0) (0,1) (0,2)1 2 3 4 5 6 7 8 9 10 11
Rotate Clockwise
(0,0)
(0,1)
(0,2)
(1,0)
(1,1)
(1,2)
(2,0)
(2,1) …
(2,1)
(2,2)
(1,2) … 4 8 1 5 9 2 6

8. Group Work
Grab a partner and write out a method rotateClockwist() for the Picture class that will return an image rotated 90 degrees in a clockwise direction.
Can we rotate the image in place?