in image sampling, better handling of numeric precision to avoid roundoff
in image sampling, better handling of numeric precision to avoid roundoff

markraz/vtp,nakijun/vtp,seanisom/vtp,seanisom/vtp,seanisom/vtp,markraz/vtp,nakijun/vtp,markraz/vtp,nakijun/vtp,seanisom/vtp,nakijun/vtp,seanisom/vtp,markraz/vtp,nakijun/vtp,markraz/vtp