saucecontrol

The old bilinear filter did not sample all pixels when downscaling -- it behaves more like a point filter with a 4px square window instead of 1. A proper bilinear filter is expected to blur because that's the nature of linear resampling. The Adaptive mode does use a sharpening kernel, because if you sample all input pixels, you must choose a balance between blurring and ringing. Depending on resampling ratio, you'll get either a Catmull-Rom cubic filter or a 3-lobed spline filter that has the same visual characteristics. You can read more about the math behind those filters here at https://legacy.imagemagick.org/Usage/filter/#cubics . There is no "edge sharpening pass" -- the sharpening is part of the cubic resampling kernel.