See attached test program. With pixman-0.9.6-43-gddfb69a, which includes Søren's "adjust" fix, the first row of pixels is 8d8d8d8d bebebebe bebebebe bebebebe bebebebe bebebebe bebebebe bebebebe 00000000 00000000 So I wonder why in this case we're sampling outside the source image. I thought the purpose of "adjust" was to subtract an amount equal to half the size of a *source* pixel from 'v', but it appears to not be doing that. Rob -- "He was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was upon him, and by his wounds we are healed. We all, like sheep, have gone astray, each of us has turned to his own way; and the LORD has laid on him the iniquity of us all." [Isaiah 53:5-6]