The first algorithm mentioned in the article is not a one-pass Paeth algorithm. The first algorithm in the article is a pure trigonometry algorithm. A one pas

The first algorithm mentioned in the article is not a one-pass Paeth algorithm. The first algorithm in the article is a pure trigonometry algorithm. A one pass Paeth algorithm produces identical results to the typical three pass implementation, because there is only one round of trigonometry up front, so there is only one round of round-off. Once the shear amounts are calculated, the rest is just integer pixel shears.