Can someone take a look at this code for me and tell me what I need to change to get my negateRed method working properly. It is supposed to change every third element in the array( starting at 0, 3, 6, 9, etc ) but instead it changes every single value in my array. Thanks.

import java.util.Scanner;

import java.io.File; import java.io.PrintWriter;

public class PPM { public static void main ( String args[] ) { try { System.out.print ( " PPM Image Processor " ); Scanner keyboard = new Scanner ( System.in ); System.out.print ( " Enter input filename: " ); String inFile; inFile = keyboard.next(); File file = new File( inFile ); Scanner input = new Scanner ( file );

String first = input.next(); int columns = input.nextInt(); int row = input.nextInt(); int max = input.nextInt(); int x = ( columns * 3 ); int y = 0; int buffer[] = new int [x];

Scanner keyboardTwo = new Scanner ( System.in ); String outFile; System.out.print ( "Enter output filename: " ); outFile = keyboardTwo.next();

PrintWriter writer = new PrintWriter ( outFile ); writer.println ( first ); writer.print ( columns ); writer.printf ( " %d", row ); writer.printf ( " %d ", max ); while ( input.hasNext() ) { if ( y < x ) { int v = input.nextInt(); buffer[y] = v; negateRed ( buffer, columns ); writer.println ( buffer[y++] ); } else { int k = 0; int v = input.nextInt(); buffer[k] = v; negateRed ( buffer, columns ); while ( k < x ) { writer.println ( buffer[k++] ); } } y = 0; }

writer.close(); }

catch ( Exception ex ) { System.out.println ( "An error has occurred!" ); ex.printStackTrace(); } }

/** * negateRed * * This method negates the red value in the image. All P3-format * PPM images have an image depth of 255, which are used in * the method's calculations. * * @param buffer an integer array containing the image buffer * @param columns an integer w/ the number of columns in the image * @return NONE */ public static void negateRed ( int [] buffer, int columns ) { int x = columns * 3; for ( int i = 0; i < x; i++ ) { if ( i % 3 == 0 ) { buffer[i] = 255 - buffer[i]; }

}

} }