Ported r2576 from ZXing
Ported r2576 from ZXing

Original commit message: "Better take on InvertedLuminanceSource --
allow possibility of rotation and efficient un-inversion"

SinnerSchraderMobileMirrors/ZXingObjC,peacemoon/ZXingObjC,davidjackman/ZXingObjC,Kevin775263419/ZXingObjC,adan016/ZXingObjC,jebai0521/ZXingObjC,YotrolZ/ZXingObjC,jianwoo/ZXingObjC,zilaiyedaren/ZXingObjC,wuxsoft/ZXingObjC,davidjackman/ZXingObjC,TheLevelUp/ZXingObjC,zeffon/ZXingObjC,tejesh-alimilli/ZXingObjC,benjohnde/ZXingObjC,elegion/ios-pods-ZXingObjC,Kevin775263419/ZXingObjC,Stocard/ZXingObjC,JeremyPacker/ZXingObjC,cortices/ZXingObjC,adan016/ZXingObjC,xuxubin/ZXingObjC,cortices/ZXingObjC,rowliny/ZXingObjC,sdhzwm/ZXingObjC,benjohnde/ZXingObjC,rkpant/ZXingObjC,tejesh-alimilli/ZXingObjC,YotrolZ/ZXingObjC,Kalvar/ZXingObjC,trsathya/ZXingObjC,ufs-slizhik/ZXingObjC,sdhzwm/ZXingObjC,elegion/ios-pods-ZXingObjC,zilaiyedaren/ZXingObjC,fanwenkai/ZXingObjC,rowliny/ZXingObjC,ufs-slizhik/ZXingObjC,jebai0521/ZXingObjC,rkpant/ZXingObjC,TheLevelUp/ZXingObjC,RockyAo/ZXingObjC,fanwenkai/ZXingObjC,peacemoon/ZXingObjC,RockyAo/ZXingObjC,trsathya/ZXingObjC,zeffon/ZXingObjC,wuxsoft/ZXingObjC,fuzhiqiang1989/ZXingObjC,fuzhiqiang1989/ZXingObjC,SinnerSchraderMobileMirrors/ZXingObjC,jianwoo/ZXingObjC,xuxubin/ZXingObjC,Stocard/ZXingObjC,JeremyPacker/ZXingObjC,SinnerSchraderMobileMirrors/ZXingObjC,Kalvar/ZXingObjC,SinnerSchraderMobileMirrors/ZXingObjC