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Added sharpness filter #942

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commented Jun 7, 2013

When tiles are resized, a sharpening filter is applied. The sharpness intensity will vary depending on zoom level. This can be adjusted by changing these lines in overviewer_core/

[495] # Intensity of the sharpness filter when zoomed all the way in, range = [0, 1]
[496] initial_sharpness = 0.4
[497] # Reduction in the filter's intensity for each level zoomed out, range = [0, 1]
[498] decay_rate = 0.5

Sharpness can range from 0 (no effect) to 1 (maximum effect). If initial_sharpness = 0, the code for the sharpening filter is never executed. For each level zoomed out, the intensity is multiplied by decay_rate. If the decay_rate is set to 1, the effect intensity will stay fixed regardless of zoom.

Things that should probably be evaluated before being enabled in master:

  • Impact on running time (is it too slow?)
  • Subjective measures of quality (is it ugly, good looking, what?)
  • Best values for intensity/decay (what is the proper balance?)

rakama added some commits Jul 23, 2012

merged with upstream/master, created 'lemon' branch to add flavor, at…
…tempted to optimize base_occluded in base.c, should improve performance by 5% but need to verify that it checks hidden primitives properly

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commented May 6, 2014

(just a quick note: this is being pushed off till it can be integrated into oil, as part of a more general image post-processing step)

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