I believe the problem is that we are flip flopping between vertical
first and horizontal first in the resampling passes, based on the area
of the intermediate representation. The horizontal and vertical passes
are very different speed on Panther. Vertical is much slower. The speed
difference is greatly improved on Tiger. We used the one with the
larger intermediate area. It may be we should reexamine that decision.
856 x 1080:
Area for H first: 1728*1080 = 1866240 <---
Area for V first: 856*2180 = 1866080
857 x 1081:
Area for H first: 1728*1081 = 1867968
Area for V first: 857*2180 = 1868260 <---
If you want to take matters into your own hands, you can do the scale
yourself by calling the two unidimensional shear bottleneck functions
to do the resampling. This would allow you to do things like always do
the horizontal pass first.
