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Get and save color components

The red, green, and blue values for the same pixel location in each of the pictures are obtained and saved.

Compute a new set of color values

A new set of red, green, and blue color values are computed as the sum of scaled versions of the pixel colors from the rabbit image pixel and the penguinimage pixel.

The nature of the scaling

The scaling is such that the pixel colors from the rabbit image contribute most heavily to output pixels to the left of center and pixel colors from thepenguin image contribute most heavily to output pixels to the right of center.

You can see the effect of this scaling algorithm in Figure 3 .

The pixels in the horizontal center

The pixels along a vertical line at the center of the output image contain equal contributions of colors from both images.

End of discussion

That concludes the explanation of the code in this program.

You can view the drawSun and crop methods in Listing 6 near the end of the module.

Run the program

I encourage you to copy the code from Listing 6 . Compile the code 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.

Click Prob05a.jpg and Prob05b.jpg to download the required input image files.

Summary

In this module, you learned how to merge two pictures.

While not a requirement of the course, you can select the following link to view an optional online video lecture on the material in this module.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java OOP: Merging Pictures
  • File: Java3030.htm
  • Published: 08/07/12
Disclaimers:

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.

Complete program listing

A complete listing of the program discussed in this module is provided in Listing 6 below.

Listing 6 . Complete program listing.
/*File Prob05 Copyright 2008 R.G.Baldwin *********************************************************/import java.awt.Color; import java.awt.Graphics2D;import java.awt.Graphics; import java.awt.GradientPaint;import java.awt.geom.Ellipse2D; public class Prob05{//DO NOT MODIFY THE CODE IN THIS CLASS DEFINITION. public static void main(String[]args){ new Prob05Runner().run();}//end main method }//end class Prob05//======================================================// class Prob05Runner{public Prob05Runner(){ System.out.println("Display your name here.");}//end constructor //----------------------------------------------------//public void run(){ Picture penguin = new Picture("Prob05a.jpg");Picture hare = new Picture("Prob05b.jpg"); merge(hare,penguin);hare = crop(hare,6,58,330,252); hare.addMessage("Display your name here.",10,20);drawSun(hare); hare.show();System.out.println(hare); }//end run//----------------------------------------------------// private void drawSun(Picture pic){Graphics2D g2d = (Graphics2D)(pic.getGraphics()); int width = 75;int height = 50; int center = pic.getWidth()/2;int xCoor = center - width/2; int yCoor = 75;//Create the gradient for painting from yellow to red // with yellow at the left of the sun and red at the// right. GradientPaint gPaint = new GradientPaint(xCoor, yCoor+height/2, Color.YELLOW,xCoor+width,yCoor+height/2, Color.ORANGE);//Set the gradient and draw the ellipse g2d.setPaint(gPaint);g2d.fill(new Ellipse2D.Double( xCoor,yCoor,width,height));}//end drawSun //----------------------------------------------------////Assumes both pictures have the same dimensions. // Does a linear merge on two pictures based on the// distance of each pixel from the left side of the // picture.private void merge(Picture left,Picture right){ int width = left.getWidth();int height = left.getHeight(); double scaleL = 0;double scaleR = 0; int redL = 0;int greenL = 0; int blueL = 0;int redR = 0; int greenR = 0;int blueR = 0; Pixel pixelL = null;Pixel pixelR = null; for(int row = 0;row<height;row++){ for(int col = 0;col<width;col++){ scaleR = (double)col/width;scaleL = 1.0 - scaleR; pixelL = left.getPixel(col,row);pixelR = right.getPixel(col,row); redL = pixelL.getColor().getRed();greenL = pixelL.getColor().getGreen(); blueL = pixelL.getColor().getBlue();redR = pixelR.getColor().getRed(); greenR = pixelR.getColor().getGreen();blueR = pixelR.getColor().getBlue(); redL = (int)(redL*scaleL + redR*scaleR);greenL = (int)(greenL*scaleL + greenR*scaleR); blueL = (int)(blueL*scaleL + blueR*scaleR);pixelL.setColor(new Color(redL,greenL,blueL)); }//end inner loop}//end outer loop }//end merge//----------------------------------------------------// //Crops a Picture object to the given width and height// with the upper-left corner located at startCol and // startRow.private Picture crop(Picture pic,int startCol, int startRow,int width, int height){Picture output = new Picture(width,height); int colOut = 0;int rowOut = 0; int col = 0;int row = 0; Pixel pixel = null;Color color = null; for(col = startCol;col<startCol+width;col++){ for(row = startRow;row<startRow+height;row++){ color = pic.getPixel(col,row).getColor();pixel = output.getPixel(colOut,rowOut); pixel.setColor(color);rowOut++; }//end inner looprowOut = 0; colOut++;}//end outer loop return output;}//end crop }//end class Prob05Runner

-end-

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