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Listing 6 computes new values for the red and green components based on the existing color values for the pixel and the scalefactors computed in Listing 5 .
| Listing 6 . Apply the scale factors. |
|---|
pixel.setGreen((int)(green * greenScale));
pixel.setBlue((int)(blue * blueScale));}//end for loop |
Then Listing 6 calls the setGreen and setBlue methods on the Pixel object to set the green and blue color values to the newly computed values.
The end of the for loop
Listing 6 also signals the end of the for loop that began in Listing 4 .
Display the modified image
Finally, Listing 7 calls the explore method again to display the image shown in Figure 2 .
| Listing 7 . Display the modified image. |
|---|
pic.explore();
}//end run method}//end class Prob03Runner |
The end of the run method
Listing 7 also signals the end of the run method and the end of the Prob03Runner class.
Return control to main
The run method terminates and returns control to the main method shown in Listing 1 .
The code in the main method calls a getter method to get a reference to the Picture object.
The reference is passed to the println method, which displays the information about the Picture object in the last line of Figure 3 .
The program terminates
Then the main method terminates, at which time the program terminates and returns control to the operating system.
I encourage you to copy the code from Listing 8 , compile it and execute it. Experiment with the code, making changes, andobserving the results of your changes. Make certain that you can explain why your changes behave as they do.
You can download a copy of the required input image file here .
In this module, I showed you how to implement an algorithm that causes the green and blue color values in an image to change in a linear fashion going fromleft to right across the image.
You will learn more about abstract methods, abstract classes, and overridden methods in the next lesson. Very importantly, you will learn more about overriding the toString method.
While not a requirement of the course, you can select the following links to view optional online video lectures on the material in thismodule.
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
A complete listing of the program discussed in this module is shown in Listing 8 below.
| Listing 8 . Complete program listing. |
|---|
/*File Prob03 Copyright 2008 R.G.Baldwin
*********************************************************/public class Prob03{
public static void main(String[]args){
Prob03Runner obj = new Prob03Runner();obj.run();
System.out.println(obj.getPicture());}//end main
}//end class Prob03//======================================================//
class Prob03Runner{//Instantiate the Picture object.
private Picture pic = new Picture("Prob03.jpg");public Prob03Runner(){//constructor
System.out.println("Dick Baldwin");}//end constructor
//----------------------------------------------------////Accessor method
public Picture getPicture(){return pic;}//----------------------------------------------------//
//This method is where the action is.public void run(){
pic.addMessage("Dick Baldwin",10,20);//Display a PictureExplorer object.
pic.explore();//Get an array of Pixel objects.
Pixel[]pixels = pic.getPixels();
//Declare working variablesPixel pixel = null;
int green = 0;int blue = 0;
int width = pic.getWidth();double greenScale = 0;
double blueScale = 0;//Scale the blue and green color components according
// to the algorithm given above.//Do not scale the red component.
for(int cnt = 0;cnt<pixels.length;cnt++){
//Get blue and green values for current pixel.pixel = pixels[cnt];green = pixel.getGreen();
blue = pixel.getBlue();//Compute the column number and use it to compute
// the scale factor.int col = cnt%width;
greenScale = (double)(width - col)/width;blueScale = (double)(col)/width;
//Apply the scale factor.pixel.setGreen((int)(green * greenScale));
pixel.setBlue((int)(blue * blueScale));}//end for loop
//Display a PictureExplorer object.pic.explore();
}//end run method}//end class Prob03Runner |
-end-
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