/*# proc: calc_skew - takes a 1 pixel per byte image and returns an angle# proc:             of skew in degrees.# proc: sumlineexps - calculates a sum exponentials of slanted row sums. # proc:                  used to determine angle of skew in the image.*/#include <stdio.h>#include <values.h>#include <math.h>#include <defs.h>#include <deskew.h>static unsigned char *inp;static int iw, ih;/***************************************************************************/double calc_skew(pinp, piw, pih, linefunc)unsigned char *pinp; int piw, pih; double (*linefunc)();{double theta, resonance, ax, bx, cx, tol, brent();   inp = pinp; iw = piw; ih = pih;   ax  = -HIGH_ANGLE/SCALE_ANGLE;   bx  = 0.0;   cx  =  HIGH_ANGLE/SCALE_ANGLE;   tol = INCR_ANGLE / SCALE_ANGLE;   resonance = brent(ax, bx, cx, linefunc, tol, &theta);   linefunc(MAXFLOAT); /* free the internal space */   return(theta);}/***************************************************************************/double sumlineexps(theta)double theta;{unsigned char *base;static int nbres = 0, *xlist, *ylist;int ystart, yfinal, ylef, yrit;int j, n, y, num, *address, bx, by, bw, bh;double rsp, yimax, tantheta;static double pcave;   if (!nbres)                          /* first time through but only  */   {                                    /*   !!--for this image--!!     */      find_corners8(&bx, &by, &bw, &bh, inp, iw, ih);      pcave = (double)pixelcnt8(inp, iw*ih) / (double)bh;   }   if (theta > MAXFLOAT / 1000.0)       /* a huge theta value indicates */   {                                    /* the last call for this image */      nbres = 0;                        /* time to prepare for next one */      free(xlist); free(ylist);      return MAXFLOAT;   }   tantheta = tan(PIBY180 * (double)theta);      /* rad  */   yimax  = (double)iw * tantheta;   ystart = (int)max(0, -yimax);   yfinal = (int)min(ih-1, ih-1-yimax);   ylef = ystart;   yrit = ystart + (int)yimax;   bres_line_alloc(0,ylef, iw-1,yrit, &xlist, &ylist, &num, &nbres);   /* overwrite ylist with addresses in the raster, calling it address  */   for ( j = 0, address = ylist ; j < num ; j++ )      address[j] = ylist[j]*iw + xlist[j];   for ( rsp = 0.0, base = inp, y = ystart ; y <= yfinal ; y++ )   {      for ( j = n = 0 ; j < num ; j++ )         if (*(base + address[j]))            n++;      rsp += exp((double)n / pcave);      base += iw;   }   return(-rsp);        /* minimize function rather than maximizing it   */}