The wife likes to keep a hard copy of most pictures of the kids, this includes some taken by me and some taken by professional photographers. For the second time we've had prints returned and in only one nostril n each (different sides each time) there's a green/blue colour. I've ruled out my editing as there's some not edited by me. It's can't be the printers deliberately doing it as it's happened several times over a period of months. Pictures taken literally second apart in same light and same position have different nostrils affected. It only ever effects the nostrils of the children, but is always present but only in one nostril, I'm not overly fussed as anything more special goes through a better printer, but it would be nice to understand what causes this. Any ideas?