3.7 Java3006: implementing a space-wise linear color-modification

Revised: Sat Apr 02 16:43:04 CDT 2016

This page is included in the following Books:

• ITSE 2321 - Object-Oriented Programming (Java)
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
  • Viewing tip
    • Figures
    • Listings
• Preview
• Discussion and sample code
• Run the program
• Summary
• What's next?
• Online video links
• Miscellaneous
• Complete program listing

Preface

This module is one of a series of modules designed to teach you about Object-Oriented Programming (OOP) using Java.

The program described in this module requires the use of the Guzdial-Ericson multimedia class library. You will find download, installation, and usageinstructions for the library at Java OOP: The Guzdial-Ericson Multimedia Class Library .

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the Figures and Listings while you are reading about them.

Figures

• Figure 1 . The raw image.
• Figure 2 . The modified image.
• Figure 3 . Text output on the command-line screen.

Listings

• Listing 1 . The driver class named Prob03.
• Listing 2 . Beginning of the class named Prob03Runner.
• Listing 3 . The beginning of the run method.
• Listing 4 . Beginning of the for loop.
• Listing 5 . Compute the column number and scale factors.
• Listing 6 . Apply the scale factors.
• Listing 7 . Display the modified image.
• Listing 8 . Complete program listing.

Preview

The program that I will explain in this module is designed to be used as a test of the student's understanding of programming using Java andEricson's media library.

The student is provided an image file named Prob03.jpg along with a written specification of a space-wise linear image modification algorithm.

Implement the algorithm

The primary purpose of the test is to determine if the student can implement the algorithm and also satisfy some requirements for text output on the commandline screen. Among other things, this requires that the student be able to:

• Create a Picture object from an image file.
• Write an accessor method to return a reference to the Picture object.
• Modify the pixels in the picture according to the specified algorithm.
• Display the raw picture and the modified picture in PictureExplorer objects by calling the explore method on the Picture object before and after it is modified.

The algorithm

Scale the blue and green color components by a scale factor that is less than or equal to 1.0. The green scale factor:

• Is equal to 1.0 on the left side of the image
• Is equal to 0.0 on the right side of the image
• Decreases linearly with distance going from left to right across the image.

The blue scale factor

• Is 0.0 on the left side of the image
• Is 1.0 on the right side of the image
• Increases linearly with distance going from left to right across the image.

Do not scale the red color component.

The program output

The program produces the images shown in Figure 1 and Figure 2 and produces the output text shown in Figure 3 on the command line screen.

Figure 1 - The raw image.