#ifndef BLACKBARS_H
#define BLACKBARS_H
/* Calibrated preset-0 edge probes on this G4. Return -1 for an ambiguous
 * or dark frame so darkness alone cannot switch the active capture mode. */
static inline int letterbox_candidate(const unsigned black[16],const unsigned char color[16][3]) {
 const unsigned interior[]={2,6,10,15};unsigned lit=0;
 for(unsigned i=0;i<4;i++){
  unsigned r=interior[i],peak=color[r][0];
  for(unsigned c=1;c<3;c++)if(color[r][c]>peak)peak=color[r][c];
  if(black[r]<20 && peak>35)lit++;
 }
 if(lit<2)return -1;
 unsigned top=(black[3]+black[11]+black[12])/3;
 unsigned bottom=(black[1]+black[5]+black[9])/3;
 if(top>=55 && bottom>=25)return 1;
 if(top<20 && bottom<20)return 0;
 return -1;
}
#endif