bool UFUnion(int p, int q)
{
int i = UFFind(p), j = UFFind(q);
if (i == j) return false;
if (size[i] > size[j])
id[j] = i;
else if (size[i] < size[j])
id[i] = j;
else
{
id[j] = i;
size[i]++;
}
count--;
return true;
}
int RemoveBackground(Image *thresholded_image)
{
// Dimension Space for label image and LabelSets
Image *label_image = malloc(sizeof(Image)) ;
UnionFind *LabelSets = malloc(sizeof(UnionFind)) ;
if(LabelSets == NULL || label_image == NULL)
{
return(0) ;
}
// Create the Union Find to have 255 distinct sets
UFCreate(255,LabelSets) ;
int A[4],i,j,k,row,col ;
GetSize(thresholded_image,&row,&col) ;
SetSize(label_image,row,col) ;
// Initialize the label image to 0
Color clr,pixel ;
for(i=0;i<row;i++)
{
for(j=0;j<col;j++)
{
clr.red=0 ;
clr.blue=0 ;
clr.green=0 ;
SetPixel(label_image,i,j,clr) ;
}
}
// LabelCounter will count how many labels I have set
int LabelCounter=1 ;
// Loop over the inner rows and columns
for(i=1;i<row-1;i++)
{
for(j=1;j<col-1;j++)
{
// For each inner pixel, check to see if it is a
// background pixel
clr = GetPixel(thresholded_image,i,j) ;
if(clr.red != 0)
{
// If it then get the labels of the pixels in the
// 1,2,3,4 positions. These get stored in the A array.
pixel=GetPixel(label_image,i-1,j-1) ;
A[0]=pixel.red ;
pixel=GetPixel(label_image,i-1,j) ;
A[1]=pixel.red ;
pixel=GetPixel(label_image,i-1,j+1) ;
A[2]=pixel.red ;
pixel=GetPixel(label_image,i,j-1) ;
A[3]=pixel.red ;
// Now count how many zero labels you have and find the
// minimum non-zero label.
int zerocount=0 ;
int minval = 255 ;
for(k=0;k<4;k++)
{
if(A[k]==0)
{
zerocount++ ;
}
else
{
if(A[k] < minval)
{
minval = A[k] ;
}
}
}
// if all the labels are zero, then the i,jth pixel is
// set to a new label
if(zerocount==4)
{
pixel.red = LabelCounter ;
SetPixel(label_image,i,j,pixel) ;
LabelCounter++ ;
}
else
{
// if there are non-zero labels then set the pixel's
// label to the smallest non-zero one. Union the sets
// as you go also.
pixel.red = minval ;
SetPixel(label_image,i,j,pixel) ;
for(k=0;k<4;k++)
{
if(A[k] != 0 && A[k] != minval)
{
UFUnion(A[k],minval,LabelSets) ;
}
}
}
}
}
}
// Find which label each pixel should be. Keep a count of how many of
// each label are used
int label[255] ;
for(i=0;i<255;i++)
{
label[i]=0 ;
}
for(i=0;i<row;i++)
{
for(j=0;j<col;j++)
{
pixel = GetPixel(label_image,i,j) ;
if(pixel.red != 0)
{
label[UFFind(pixel.red, LabelSets)]++ ;
pixel.red = (5*(1+UFFind(pixel.red, LabelSets)))%255 ;
pixel.green = (5*pixel.red)%255 ;
pixel.blue = (10*pixel.red)%255 ;
SetPixel(label_image, i, j, pixel) ;
}
}
}
// Which label represents the majority of non-background pixels
int max = 0 ;
int maxi = -1 ;
int secondi = -1 ;
for(i=0;i<255;i++)
{
if(label[i] > max)
{
secondi = maxi ;
max = label[i] ;
maxi = i ;
}
}
// Write out the color if it is not the largest label or if it is a
// background pixel.
secondi = (5*(1+maxi))%255 ;
for(i=0;i<row;i++)
{
for(j=0;j<col;j++)
{
pixel=GetPixel(label_image,i,j) ;
if(pixel.red != secondi && pixel.red != 0)
{
pixel.red=0 ;
pixel.blue=0 ;
pixel.green=0 ;
SetPixel(thresholded_image, i, j, pixel) ;
}
else
{
pixel.red=255 ;
pixel.blue=255 ;
pixel.green=255 ;
SetPixel(thresholded_image, i, j, pixel) ;
}
}
}
// free up some memory declared here.
free(label_image) ;
free(LabelSets) ;
return(1) ;
}
int UFFind(int p)
{
if (p == id[p]) return;
return id[p] = UFFind(id[p]);
}