Looking for faster area sampling downscaling...

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I am scaling a 1280x720px image down to about 20x11 grayscale for analysis of the pixel values. I find that scaling with INTER_AREA provides the best results in terms of stability of the values (lack of jitter/flicker) but is about 10x slower than the next nearest competitor (INTER_LANCZOS4). Just wondering if anyone has any ideas on alternatives that might yield results between these two. The other interpolation options (neartest, linear, cubic) perform faster but provide worse results for this case.