PNG Encoder MK-II

//Encoder Class
package com.ignatieff.tepng;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class Encoder {

    BufferedImage img;

    public Encoder(BufferedImage image){
        img = image;
    }

    public Encoder(String path) throws IOException{
        this(loadImage(path));
    }

    private static BufferedImage loadImage(String path) throws IOException{
        File f = new File(path);
        BufferedImage i = ImageIO.read(f);
        return i;
    }

    public void saveImage(String path) throws IOException{
        File f = new File(path);
        ImageIO.write(img, "png", f);
    }

    public static int getBit(int input, int bit){
        if((input & (1 << bit)) != 0)return 1;
        return 0;
    }

    private boolean writeChar(char c, int x, int y){
        int i = translateChar(c);
        if(i==-1)return false;
        encodeData(i, x, y);
        return true;
    }

    private char readChar(int x, int y){
        return translateInt(decodeData(x,y));
    }

    public void encodeMessage(String message){
        encodeMessage(message, 1);
    }

    public void encodeMessage(String message, String key){
        encodeMessage(message, key.hashCode());
    }

    public String getMessage(){
        return getMessage(1);
    }

    public String getMessage(String key){
        return getMessage(key.hashCode());
    }

    public void encodeMessage(String message, int key){
        int max = img.getHeight() * img.getWidth();
        if(message.length()+5 >= max){return;}
        Group g = new Group(max, key);
        char[] c = (message+"'.!.'").toCharArray();
        int x = 0, y = 0;
        for(int i=0;i<c.length;i++){
            if(writeChar(c[i],x,y)){
                x+=g.PRIME;
                while(x>=img.getWidth()){x-=img.getWidth();y++;}
                if(y>=img.getHeight()){y%=img.getHeight();}
            }
        }
    }

    public String getMessage(int key){
        String r = "";
        Group g = new Group(img.getHeight() * img.getWidth(), key);
        int x=0, y=0;
        while(!r.contains("'.!.'")){
            while(x>=img.getWidth()){x-=img.getWidth();y++;}
            if(y>=img.getHeight()){y%=img.getHeight();}
            r+=readChar(x,y);
            x+=g.PRIME;
        }
        return r.substring(0,r.length()-5);
    }

    private int decodeData(int x, int y){
        int argb = img.getRGB(x, y);

        int r = (argb)&0xFF;
        int g = (argb>>8)&0xFF;
        int b = (argb>>16)&0xFF;

        int rDec = (getBit(r, 1) << 1) | getBit(r, 0);
        int gDec = getBit(g, 0);
        int bDec = (getBit(b, 1) << 1) | getBit(b, 0);

        int data = (bDec << 3)|(gDec << 2)|rDec;

        return data;
    }

    private void encodeData(int data, int x, int y){
        if(data>=32){return;}

        int rEnc = (getBit(data, 1) << 1)|getBit(data, 0);
        int gEnc = getBit(data, 2);
        int bEnc = (getBit(data, 4) << 1)|getBit(data, 3);
        int argb = img.getRGB(x, y);

        int r = (((argb)&0xFF) >> 2) << 2;
        int g = (((argb>>8)&0xFF) >> 1) << 1;
        int b = (((argb>>16)&0xFF) >> 2) << 2;

        int newR = r | rEnc;
        int newG = g | gEnc;
        int newB = b | bEnc;

        int newARGB = (newB << 16)|(newG << 8)|newR;

        img.setRGB(x, y, newARGB);
    }

    public static char translateInt(int i){
        if(i <= 25)return (char)(i+65);
        switch(i){
            case 26:
                return ' ';
            case 27:
                return '.';
            case 28:
                return ',';
            case 29:
                return '!';
            case 30:
                return '?';
            case 31:
                return '\'';
        }
        return '#';
    }

    public static int translateChar(char c){
        if((int)c >= 65 && (int)c <=90){
            return (int)c-65;
        }
        if((int)c >= 97 && (int)c <=122){
            return (int)c-97;
        }
        switch(c){
            case ' ':
                return 26;
            case '.':
                return 27;
            case ',':
                return 28;
            case '!':
                return 29;
            case '?':
                return 30;
            case '\'':
                return 31;
        }
        return -1;
    }

}


//Group Class
package com.ignatieff.tepng;

import java.math.BigInteger;

public class Group {
    public int PRIME;

    public Group(int size, int hash){
        int p = (int)Math.abs(hash % size);
        int i=0;
        BigInteger b = BigInteger.valueOf(p);
        while(!b.isProbablePrime(10)){
            int m = 1;++i;
            if(i%2==0){m*=-1;}
            b = BigInteger.valueOf(p+m*i);
        }
        PRIME = b.intValue();
    }
}