void Private_Impl::retrieve ( unsigned char *data,RASPICAM_FORMAT type ) {
     if ( callback_data._buffData.size==0 ) return;
     if ( type!=RASPICAM_FORMAT_IGNORE ) {
         cerr<<__FILE__<<":"<<__LINE__<<" :Private_Impl::retrieve type is not RASPICAM_FORMAT_IGNORE as it should be"<<endl;
     }
     memcpy ( data,callback_data._buffData.data,getImageTypeSize ( State.captureFtm ) );
 }
size_t Private_Impl::getImageBufferSize() const {
    return getImageTypeSize ( getFormat() );
}