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jwilk / didjvu

DjVu encoder with foreground/background separation
https://jwilk.net/software/didjvu
GNU General Public License v2.0
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Please explain subsampling and justify the defaults #11

Open jwilk opened 8 years ago

jwilk commented 8 years ago

Issue reported by @jsbien:

Why the default foreground subsampling is larger than the default background one?

jwilk commented 7 years ago

The default settings (--fg-subsample=6, --bg-subsample=3) were chosen so that I can use djvumake to compose DjVu by default. djvumake uses these subsample ratios, and they are not configurable. Intuitively, lower quality for the foreground layer makes sense, because in the typical case it's solid color (most often black).