#ifndef __IMG_THIN_CPP__#define __IMG_THIN_CPP__#include "fvstypes.h"#include "fvsimage.h"#include "img_thin.h"#define REMOVE_P    { img[x][y]=0x80; changed = TRUE; }/*From     : Nadeem Ahmed (umahmed@cc.umanitoba.ca)Subject  : Thinning AlgorithmNewsgroup: borland.public.cppbuilder.graphicsDate :1998/02/23 Here is that thinning algorithm:                            9 2 3                            8 1 4                            7 5 6For each pixel(#1, above), we have 8 neighbors (#'s 2-8).Step 1:a) Make sure pixel 1, has 2 to 6 (inclusive) neighborsb) starting from 2, go clockwise until 9, and count the   number of 0 to 1 transitions.  This should be equal to 1.c) 2*4*6=0  (ie either 2,4 ,or 6 is off)d) 4*6*8=0if these conditions hold, remove pixel 1.Do this for the entire image.Step 2a) same as aboveb) same as abovec) 2*6*8=0d) 2*4*8=0if these hold remove pixel 1.*//* defines to facilitate reading */#define P1 img[x-1][y-1]#define P2 img[x][y-1]#define P3 img[x+1][y-1]#define P4 img[x-1][y]#define P5 img[x+1][y]#define P6 img[x-1][y+1]#define P7 img[x][y+1]#define P8 img[x+1][y+1]/* a) Make sure it has 2 to 6 neighbours */#define STEP_A  n = 0; /* number of neighbours */ \                if (P2) n++; if (P3) n++; if (P5) n++; if (P8) n++; \                if (P7) n++; if (P6) n++; if (P4) n++; if (P1) n++; \                if (n>=2 && n<=6)/* b) count number 0 to 1 transsitions */#define STEP_B  t = 0; /* number of transitions */ \                if (!P1 && P2) t++; if (!P2 && P3) t++; \				if (!P3 && P5) t++; if (!P5 && P8) t++; \                if (!P8 && P7) t++; if (!P7 && P6) t++; \                if (!P6 && P4) t++; if (!P4 && P1) t++; \                if (t==1) template <class itemType>FvsError_t ImageThin(FvsImage<itemType> & img){    uint32_t x, y, n, t;    bool_t changed = TRUE;    while (changed==TRUE)    {        changed = FALSE;        for (y=1; y<img.height()-1; y++)        for (x=1; x<img.width()-1; x++)        {            if (img[x][y]==0xFF)            {                STEP_A                {                    STEP_B                    {                        /*                        c) 2*5*7=0  (ie either 2,5 ,or 7 is off)                        d) 5*7*4=0                        */                        if (P2*P5*P7==0 && P5*P7*P4==0)                            REMOVE_P;                    }                }            }        }        for (y=1; y<img.height()-1; y++)        for (x=1; x<img.width()-1; x++)            if (img[x][y]==0x80)                img[x][y] = 0;        for (y=1; y<img.height()-1; y++)        for (x=1; x<img.width()-1; x++)        {            if (img[x][y]==0xFF)            {                STEP_A                {                    STEP_B                    {                        /*                        c) 2*7*4=0                        d) 2*5*4=0                        */                        if (P2*P7*P4==0 && P2*P5*P4==0)                            REMOVE_P;                    }                }            }        }        for (y=1; y<img.height()-1; y++)        for (x=1; x<img.width()-1; x++)            if (img[x][y]==0x80)                img[x][y] = 0;    }    return FvsOk;}#endif // __IMG_THIN_CPP__