Description

CV Project5: Image Compression via Distance Transform Java
Student: Fengzhang Du
Algorithm Steps for Compute Image Compression:
step 0: inFile <- open input file
numRows, numCols, minVal, maxVal <- read from inFile dynamically allocate zeroFramedAry with extra 2 rows and 2 cols dynamically allocate skeletonAry with extra 2 rows and 2 cols open outFile_1, outFile_2
Step 1: skeletonFileName <- args[0] + “_skeleton.txt”
Step 2: skeletonFile <- open( skeletonFileName )
Step 3: decompressedFileName <- args[0] + “_decompressed.txt” Step 4: decompressFile <- open (decompressedFileName)
Step 5: loadImage (inFile, zeroFramedAry)
Step 6: compute8Distance (zeroFramedAry, outFile1)
Step 7: skeletonExtraction (zeroFramedAry, skeletonAry, skeletonFile,
outFile1) // perform lossless compression
Step 8: skeletonExpansion (zeroFramedAry, skeletonFile, outFile2)
// perform decompression
step 9: Output numRows, numCols, newMinVal, newMaxVal to decompressFile
Step 10: ary2File (zeroFramedAry, decompressFile)
Step 11: close all files
Source Code
import java.io.*;
import java.util.Scanner;

public class Main{
public static void main(String[] args) throws IOException, InterruptedException{
String fileName = args[0].replace(“.txt”, “”);
String skeleton_name = fileName+”_skeleton.txt”;
String decompressed_name = fileName+”_decompressed.txt”;
try(
Scanner input = new Scanner(new BufferedReader(new FileReader(args[0])));
// 2 output files
BufferedWriter output1 = new BufferedWriter(new FileWriter(args[1], true));
BufferedWriter output2 = new BufferedWriter(new FileWriter(args[2]));

BufferedWriter skeletonFile = new BufferedWriter(new FileWriter(skeleton_name, true));
BufferedWriter decompressedFile = new BufferedWriter(new
FileWriter(decompressed_name));
// open the compressed skeleton
Scanner skeletonFileReader = new Scanner(new BufferedReader(new
FileReader(skeleton_name)));
){
// Read and store image header.
int header[] = new int[4];
for (int i=0; i<4; i++){
if (input.hasNextInt()) header[i] = input.nextInt();
}
ImageProcessing img = new ImageProcessing(header[0], header[1], header[2], header[3]);
img.loadImg(input);
img.compute8Distance(output1);
img.skeletonExtraction(output1, skeletonFile);
img.skeletonExpansion(output2, skeletonFileReader);
img.ary2File(decompressedFile, output2);
}
}
}

class ImageProcessing{
// field
int numRows=0, numCols=0, minVal=0, maxVal=0, newMin=0, newMax=0;
int[][] zeroFramedAry;
int[][] skeletonAry;
int f = 1; // frame size

// constructor
ImageProcessing(int numRows, int numCols, int minVal, int maxVal){
this.numRows = numRows;
this.numCols = numCols;

this.minVal = minVal;
this.maxVal = maxVal;
}

// methods
void loadImg(Scanner input){
this.zeroFramedAry = new int[this.numRows+2][this.numCols+2];
this.skeletonAry = new int[this.numRows+2][this.numCols+2];
for(int i=f; i<numRows+f; i++){
for(int j=f; j<numCols+f; j++){
if(input.hasNextInt()) zeroFramedAry[i][j] = input.nextInt();
else{
System.out.println( “Corrupted Image input data!”);
System.exit(0);
}
}
}
}

void compute8Distance(BufferedWriter output) throws IOException{
// all 4 methods only involve zeroFramedAry
firstPass8Distance();
reformatPrettyPrint(“1st pass Distance Transform: Result of firstPass8Distance: “,
zeroFramedAry, output);
secondPass8Distance();
reformatPrettyPrint(“2nd pass Distance Transform: Result of secondPass8Distance: “,
zeroFramedAry, output);
}

void firstPass8Distance(){
for (int i=f; i<numRows+f; i++){
for (int j=f; j<numCols+f; j++){
int tempMin = 10000;
if (zeroFramedAry[i][j] > 0){
// loop through all the neighbors
for (int k=i-1; k<=i; k++){
for (int d=j-1; d<=j+1; d++){
if (k >= i && d >=j) break;
else{
tempMin = Math.min(tempMin, zeroFramedAry[k][d]);
}
}
}
zeroFramedAry[i][j] = tempMin+1;
}
}
}
}

void secondPass8Distance(){
newMax = 0;

for (int i=numRows; i>=f; i–){
for (int j=numCols; j>=f; j–){
if (zeroFramedAry[i][j] > 0){
// loop through all the neighbors
for (int k=i+1; k>=i; k–){
for(int d=j+1;d>=j-1; d–){
if(k<=i && d<=j) break;
else{
zeroFramedAry[i][j] = Math.min(zeroFramedAry[i][j],
zeroFramedAry[k][d]+1);
newMin = Math.min(newMin, zeroFramedAry[k][d]);
newMax = Math.max(newMax, zeroFramedAry[k][d]);
}
}
}
}
}
}
}

boolean isLocalMaxima(int i, int j){
// loop through all the neighbors
for (int k=i-1; k<=i+1; k++){
for (int d=j-1; d<=j+1; d++){
if(zeroFramedAry[i][j]<zeroFramedAry[k][d]) {
return false;
}
}
}
return true;
}

void computeLocalMaxima() throws IOException{
for (int i=f; i<numRows+f; i++){
for (int j=f; j<numCols+f; j++){
if (isLocalMaxima(i, j)){
skeletonAry[i][j] = zeroFramedAry[i][j];
}else{
skeletonAry[i][j] = 0;
}
}
}
}

void extractLocalMaxima(BufferedWriter output) throws IOException{
output.write(Integer.toString(numRows) + ” ” + Integer.toString(numCols) + ” “);
output.write(Integer.toString(newMin) + ” ” + Integer.toString(newMax) + ” “);
for (int i=f; i<=numRows; i++){
for(int j=f; j<=numCols; j++){
if (skeletonAry[i][j] > 0){
output.write(i+” ” + j+” “+skeletonAry[i][j]+” “);

}
}
}
output.close();

}

void skeletonExtraction(BufferedWriter output1, BufferedWriter skeletonFile) throws
IOException{
computeLocalMaxima();
reformatPrettyPrint(“Local Maxima: Result of computeLocalMaxima;”, skeletonAry, output1);
extractLocalMaxima(skeletonFile);
}

void skeletonExpansion(BufferedWriter output2, Scanner skeletonFileReader) throws IOException,
InterruptedException{
// set array to all zeros.
this.zeroFramedAry = new int[this.numRows+2][this.numCols + 2];
this.skeletonAry = new int[this.numRows+2][this.numCols + 2];
loadSkeleton(output2, skeletonFileReader);
firstPassExpension();
reformatPrettyPrint(“1st pass Expansion: Result of firstPassExpension:”, zeroFramedAry,
output2);
secondPassExpension();
reformatPrettyPrint(“2nd pass Expansion: Result of secondPassExpension:”, zeroFramedAry,
output2);
}

void loadSkeleton(BufferedWriter output2, Scanner skeletonFileReader) throws IOException{
// load header from compressed skeletonFileReader
output2.write(“Compressed Skeleton: “);
int newHeader[] = new int[4];
for (int i=0; i<4; i++){
if (skeletonFileReader.hasNextInt()) {
newHeader[i] = skeletonFileReader.nextInt();
output2.write(newHeader[i] + ” “);
}
}
output2.write(” “);

while(skeletonFileReader.hasNextInt()){
int i = skeletonFileReader.nextInt();
int j = skeletonFileReader.nextInt();
zeroFramedAry[i][j] = skeletonFileReader.nextInt();
output2.write(i +” ” + j + ” ” + zeroFramedAry[i][j] + ” “);
}
output2.write(” “);
}

void firstPassExpension(){
for(int i=f; i<=numRows; i++){

for(int j=f; j<=numCols; j++){
if (zeroFramedAry[i][j] == 0){
// loop through all neighbors.
for (int k=i-1; k<=i+1; k++){
for (int d=j-1; d<=j+1; d++){
if (k==i && d==j) continue;
else{
zeroFramedAry[i][j] = Math.max(zeroFramedAry[i][j],
zeroFramedAry[k][d]-1);
}
}
}
}
}
}
}

void secondPassExpension(){
for(int i=numRows; i>=f; i–){
for(int j=numCols; j>=f; j–){
// loop through all neighbors for all pixels.
int tempMax = 0;
for (int k=i+1; k>=i-1; k–){
for (int d=j+1; d>=j-1; d–){
if (k==i && d==j) continue;
else{
tempMax = Math.max(tempMax, zeroFramedAry[k][d]);
}
}
}
if(zeroFramedAry[i][j]<tempMax) zeroFramedAry[i][j] = tempMax-1;
}
}
}

void ary2File(BufferedWriter decompressedFile, BufferedWriter output2) throws IOException{ //
to decompressed file
decompressedFile.write(numRows + ” ” + numCols + ” ” + minVal + ” ” + maxVal + ” “);
output2.write(” Decompressed File: “);
output2.write(numRows + ” ” + numCols + ” ” + minVal + ” ” + maxVal + ” “);
for(int i=f; i<=numRows; i++){
for (int j=f; j<=numCols; j++){
if (zeroFramedAry[i][j] >= 1){
decompressedFile.write(“1 “);
output2.write(“1 “);
}else{
decompressedFile.write(“0 “);
output2.write(“0 “);
}
}
decompressedFile.write(” “);
output2.write(” “);
}
}

void reformatPrettyPrint(String title, int [][] arr, BufferedWriter output) throws IOException
{
output.write(title + ” “);
for(int i=f; i<numRows+f; i++){
for(int j=f; j<numCols+f; j++){
if(arr[i][j] == 0){
output.write(” ” + ” “);
}else{
output.write(Integer.toString(arr[i][j]) + ” “);
}
}
output.write(” “);
}
output.write(” “);
}
}
Program Output

image1_output_2.txt
Compressed Skeleton:
30 40 0 7
2 11 1
4 11 2
5 27 5
5 28 5
6 11 3
6 27 5
6 28 5
8 11 4
8 28 6
9 28 6
9 29 6
9 31 5
10 11 5
10 22 1
10 28 6
10 29 6
10 31 5
10 32 5
10 34 4
10 36 3
10 38 2
10 40 1
11 11 5
11 28 6
12 11 5
13 11 5
13 27 5
13 28 5
14 11 5
14 27 5
15 11 5
15 27 5
16 11 5
16 27 5
17 27 5
18 27 5
19 10 7
19 11 7
19 12 7
19 13 7
19 27 5
20 10 7
20 11 7
20 12 7
20 13 7
20 27 5
21 11 7
21 12 7
21 27 5
22 27 5
22 29 4
22 31 3
22 33 2
22 35 1
23 11 6

23 12 6
23 17 4
23 18 4
23 19 4
23 20 4
23 21 4
23 22 4
23 23 4
23 24 4
23 25 4
25 11 5
25 12 5
27 11 4
27 12 4
image1_ decompressed .txt
30 40 0 7
2 11 1
4 11 2
5 27 5
5 28 5
6 11 3
6 27 5
6 28 5
8 11 4
8 28 6
9 28 6
9 29 6
9 31 5
10 11 5
10 22 1
10 28 6
10 29 6
10 31 5
10 32 5
10 34 4
10 36 3
10 38 2
10 40 1
11 11 5
11 28 6 image1_decompressed.txt

12 11 5
13 11 5
13 27 5
13 28 5
14 11 5
14 27 5
15 11 5
15 27 5
16 11 5
16 27 5
17 27 5
18 27 5
19 10 7
19 11 7
19 12 7
19 13 7
19 27 5
20 10 7
20 11 7
20 12 7
20 13 7
20 27 5
21 11 7
21 12 7
21 27 5
22 27 5
22 29 4
22 31 3
22 33 2
22 35 1
23 11 6
23 12 6
23 17 4
23 18 4
23 19 4
23 20 4
23 21 4
23 22 4
23 23 4
23 24 4
23 25 4
25 11 5
25 12 5
27 11 4
27 12 4
Next page for image 2. image2_output_1.txt

image2_output_2.txt
Compressed Skeleton:
45 64 0 7
4 31 1
6 31 2
8 11 1
8 31 3
8 52 4
9 52 4
10 11 2
10 31 4
10 52 4
11 52 4
12 11 3
12 31 5
12 52 4
13 22 1
13 24 2
13 26 3
13 28 4
13 30 5
13 31 5
13 32 5
13 34 4
13 36 3
13 38 2
13 40 1
13 52 4

14 11 4
14 31 5
14 52 4
15 52 4
16 11 5
16 31 4
16 52 4
17 52 4
18 11 6
18 31 3
18 52 4
19 52 4
20 11 7
20 32 2
20 52 4
21 4 4
21 6 5
21 8 6
21 10 7
21 11 7
21 12 7
21 14 6
21 16 5
21 18 4
21 20 3
21 22 2
21 24 1
21 52 4
22 11 7
22 31 1
22 52 4
23 31 1
23 52 4
24 11 6
24 52 4
25 31 2
25 52 4
26 11 5
26 52 4
27 31 3
27 52 4
28 11 4
28 52 4
29 32 4
29 52 4
30 11 3
30 52 4
31 32 5
31 36 3
31 52 4
32 11 2
32 22 1
32 24 2
32 26 3
32 27 3
32 30 5
32 31 5
32 32 5
32 34 4
32 36 3
32 38 2
32 40 1

32 52 4
33 27 3
33 31 5
34 11 1
35 31 4
37 31 3
39 31 2
41 31 1
image2_ decompressed .txt
45 64 0 7
4 31 1
6 31 2
8 11 1
8 31 3
8 52 4
9 52 4
10 11 2
10 31 4
10 52 4
11 52 4
12 11 3
12 31 5
12 52 4
13 22 1
13 24 2
13 26 3
13 28 4
13 30 5
13 31 5
13 32 5
13 34 4
13 36 3
13 38 2
13 40 1
13 52 4
14 11 4
14 31 5
14 52 4
15 52 4
16 11 5
16 31 4
16 52 4
17 52 4
18 11 6
18 31 3
18 52 4
19 52 4
20 11 7
20 32 2
20 52 4
21 4 4
21 6 5 image2_decompressed.txt

21 8 6
21 10 7
21 11 7
21 12 7
21 14 6
21 16 5
21 18 4
21 20 3
21 22 2
21 24 1
21 52 4
22 11 7
22 31 1
22 52 4
23 31 1
23 52 4
24 11 6
24 52 4
25 31 2
25 52 4
26 11 5
26 52 4
27 31 3
27 52 4
28 11 4
28 52 4
29 32 4
29 52 4
30 11 3
30 52 4
31 32 5
31 36 3
31 52 4
32 11 2
32 22 1
32 24 2
32 26 3
32 27 3
32 30 5
32 31 5
32 32 5
32 34 4
32 36 3
32 38 2
32 40 1
32 52 4
33 27 3
33 31 5
34 11 1
35 31 4
37 31 3
39 31 2
41 31 1