added credit for Sven Utcke's Canny code
added credit for Sven Utcke's Canny code

ThomasWalter/vigra,xiwei-zhang/vigra,martinsch/vigra,kod3r/vigra,martinsch/vigra,dagophil/vigra,cbecker/vigra,cbecker/vigra,psteinb/vigra,ThomasWalter/vigra,funkey/vigra,psteinb/vigra,mmuellner/vigra,mmuellner/vigra,kod3r/vigra,ThomasWalter/vigra,kod3r/vigra,dagophil/vigra,hmeine/vigra,DaveRichmond-/vigra,hmeine/vigra,cbecker/vigra,cha007/vigra,capturePointer/vigra,xiwei-zhang/vigra,hmeine/vigra,dagophil/vigra,capturePointer/vigra,DaveRichmond-/vigra,cha007/vigra,timoMa/vigra,funkey/vigra,dagophil/vigra,mmuellner/vigra,funkey/vigra,dstoe/vigra,timoMa/vigra,psteinb/vigra,dstoe/vigra,xiwei-zhang/vigra,dstoe/vigra,DaveRichmond-/vigra,xiwei-zhang/vigra,dagophil/vigra,martinsch/vigra,funkey/vigra,stuarteberg/vigra,cha007/vigra,timoMa/vigra,timoMa/vigra,xiwei-zhang/vigra,martinsch/vigra,ThomasWalter/vigra,stuarteberg/vigra,dstoe/vigra,cbecker/vigra,hmeine/vigra,martinsch/vigra,psteinb/vigra,mmuellner/vigra,psteinb/vigra,DaveRichmond-/vigra,dstoe/vigra,ThomasWalter/vigra,kod3r/vigra,kod3r/vigra,dagophil/vigra,mmuellner/vigra,DaveRichmond-/vigra,funkey/vigra,stuarteberg/vigra,dstoe/vigra,martinsch/vigra,cbecker/vigra,DaveRichmond-/vigra,hmeine/vigra,cha007/vigra,funkey/vigra,stuarteberg/vigra,capturePointer/vigra,stuarteberg/vigra,cha007/vigra,kod3r/vigra,capturePointer/vigra,cha007/vigra,timoMa/vigra,capturePointer/vigra,cbecker/vigra,DaveRichmond-/vigra,mmuellner/vigra,dagophil/vigra,timoMa/vigra,psteinb/vigra,xiwei-zhang/vigra,funkey/vigra,ThomasWalter/vigra,capturePointer/vigra,hmeine/vigra,stuarteberg/vigra,xiwei-zhang/vigra,timoMa/vigra,cha007/vigra,mmuellner/vigra,hmeine/vigra,kod3r/vigra,stuarteberg/vigra,dstoe/vigra,ThomasWalter/vigra,psteinb/vigra,capturePointer/vigra