/******************************************************************************************
* labelBinaryImage
******************************************************************************************/
int labelBinaryImage(Image *im) {
int nRows, nCols, levels;
int i, j;
nRows = im->getNRows( );
nCols = im->getNCols( );
/* FIRST RUN */
/* read pixel row by row, label starting from 1 */
int nextLabel = 0;
DisjSets labels;
for(i=0; i<nRows; i++) {
for(j=0; j<nCols; j++) {
/* 0 is black, 255 is white */
if (im->getPixel(i, j) != 0) {
int NW, N, W;
/* most pixels--except for top row and left column */
if (i!=0 && j!=0) { /* check pixels in the following order: NW, N, W */
NW = im->getPixel(i-1,j-1);
N = im->getPixel(i-1,j);
W = im->getPixel(i,j-1);
if (NW!=0) {
im->setPixel(i,j,NW);
if (N!=0 && W==0 && N!=NW) {
labels.unionSets(NW,N);
}
if (W!=0 && N==0 && W!=NW) {
labels.unionSets(NW,W);
}
if (W!=0 && N!=0 && W!=N) {
labels.unionSets(N,W);
}
}
else {
if (N!=0 && W==0) {
im->setPixel(i,j,N);
}
else if (N==0 && W!=0) {
im->setPixel(i,j,W);
}
else if (N==0 && W==0) {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
else if (N!=0 && W!=0) {
if (N==W) {
im->setPixel(i,j,N);
}
else {
labels.unionSets(N,W);
im->setPixel(i,j,N);
}
}
}
}
/* top left corner */
if (i==0 && j==0) {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
/* top row */
if (i==0 && j!=0) {
W = im->getPixel(i,j-1);
if (W!=0) {
im->setPixel(i,j,W);
}
else {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
}
/* left column */
if (i!=0 && j==0) {
N = im->getPixel(i-1,j);
if (N!=0) {
im->setPixel(i,j,N);
}
else {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
}
}
}
}
/* save # levels (num of objects) */
levels = labels.getNumberOfLevels( );
im->setColors(levels);
//printf("Number of objects: %d\n", levels);
/* SECOND RUN */
/* create a finalLabels vector with labels of all sets */
vector<int> finalLabels;
finalLabels.push_back(-1);
vector<int> listOfLevels = labels.getLevels( );
int label, numOfLabels = labels.getNumberOfLabels( );
for (i=1; i<=numOfLabels; i++) {
label = labels.find(i);
for (j=0; j < listOfLevels.size(); j++) {
if (label==listOfLevels[j]) {
label = j+1;
}
}
finalLabels.push_back(label);
}
/* relabel the image */
int l;
for(i=0; i<nRows; i++) {
for(j=0; j<nCols; j++) {
l = im->getPixel(i,j);
if (l>0 && l<=finalLabels.size( )) {
im->setPixel(i,j,finalLabels[l]);
}
}
}
return 0; /* OK */
}
/******************************************************************************************
* readAndLabelBinaryImage
******************************************************************************************/
int readAndLabelBinaryImage(Image *im, const char *fname) {
FILE *input;
char line[1024];
int nCols,nRows;
int levels;
int i, j;
/* open it */
if (!fname || (input=fopen(fname,"r"))==0) {
printf("readImage: Cannot open file\n");
return -1;
}
/* check for the right "magic number" */
if (fread(line,1,3,input)!=3 || strncmp(line,"P5\n",3)) {
fclose(input);
printf("readImage: Expected .pgm file\n");
return -1;
}
/* skip the comments */
do {
fgets(line,sizeof line,input);
}
while (*line=='#');
/* read the width and height */
sscanf(line,"%d %d\n",&nCols,&nRows);
im->setSize(nRows, nCols);
/* read line with # of gray levels, check if binary image */
fgets(line,sizeof line,input);
sscanf(line,"%d\n",&levels);
if (levels!=1) {
fclose(input);
printf("readImage: Expected binary .pgm file\n");
return -1;
}
/* FIRST RUN */
/* read pixel row by row, label starting from 1 */
int nextLabel = 0;
DisjSets labels;
for(i=0; i<nRows; i++) {
for(j=0; j<nCols; j++) {
int byte = fgetc(input);
if (byte==EOF) /* short file */ {
fclose(input);
printf("readImage: short file\n");
return -1;
}
else {
/* 0 is black, 255 is white */
if (byte!=0) {
int NW, N, W;
/* most pixels--except for top row and left column */
if (i!=0 && j!=0) { /* check pixels in the following order: NW, N, W */
NW = im->getPixel(i-1,j-1);
N = im->getPixel(i-1,j);
W = im->getPixel(i,j-1);
if (NW!=0) {
im->setPixel(i,j,NW);
if (N!=0 && W==0 && N!=NW) {
labels.unionSets(NW,N);
}
if (W!=0 && N==0 && W!=NW) {
labels.unionSets(NW,W);
}
if (W!=0 && N!=0 && W!=N) {
labels.unionSets(N,W);
}
}
else {
if (N!=0 && W==0) {
im->setPixel(i,j,N);
}
else if (N==0 && W!=0) {
im->setPixel(i,j,W);
}
else if (N==0 && W==0) {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
else if (N!=0 && W!=0) {
if (N==W) {
im->setPixel(i,j,N);
}
else {
labels.unionSets(N,W);
im->setPixel(i,j,N);
}
}
}
}
/* top left corner */
if (i==0 && j==0) {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
/* top row */
if (i==0 && j!=0) {
W = im->getPixel(i,j-1);
if (W!=0) {
im->setPixel(i,j,W);
}
else {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
}
/* left column */
if (i!=0 && j==0) {
N = im->getPixel(i-1,j);
if (N!=0) {
im->setPixel(i,j,N);
}
else {
im->setPixel(i,j,++nextLabel);
labels.addElement( );
}
}
}
}
}
}
/* save # levels (num of objects) */
levels = labels.getNumberOfLevels( );
im->setColors(levels);
printf("Number of objects: %d\n", levels);
/* SECOND RUN */
/* create a finalLabels vector with labels of all sets */
vector<int> finalLabels;
finalLabels.push_back(-1);
vector<int> listOfLevels = labels.getLevels( );
int label, numOfLabels = labels.getNumberOfLabels( );
for (i=1; i<=numOfLabels; i++) {
label = labels.find(i);
for (j=0; j < listOfLevels.size(); j++) {
if (label==listOfLevels[j]) {
label = j+1;
}
}
finalLabels.push_back(label);
}
/* relabel the image */
int l;
for(i=0; i<nRows; i++) {
for(j=0; j<nCols; j++) {
l = im->getPixel(i,j);
if (l>0 && l<=finalLabels.size( )) {
im->setPixel(i,j,finalLabels[l]);
}
}
}
/* close the file */
fclose(input);
return 0; /* OK */
}