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FFmpeg/doc/scaler.texi
Øyvind Kolås 3e6016622e swscale: add two spatially stable dithering methods
Both of these dithering methods are from http://pippin.gimp.org/a_dither/ for
GIF they can be considered better than bayer (provides more gray-levels), and
spatial stability - often more than twice as good compression and less visual
flicker than error diffusion methods (the methods also avoids error-shadow
artifacts of diffusion dithers).

These methods are similar to blue/green noise type dither masks; but are
simple enough to generate their mask on the fly. They are still research work
in progress; though more expensive to generate masks (which can be used in a
LUT) like 'void and cluster' and similar methods will yield superior results
2014-03-25 13:48:06 +01:00

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@anchor{scaler_options}
@chapter Scaler Options
@c man begin SCALER OPTIONS
The video scaler supports the following named options.
Options may be set by specifying -@var{option} @var{value} in the
FFmpeg tools. For programmatic use, they can be set explicitly in the
@code{SwsContext} options or through the @file{libavutil/opt.h} API.
@table @option
@anchor{sws_flags}
@item sws_flags
Set the scaler flags. This is also used to set the scaling
algorithm. Only a single algorithm should be selected.
It accepts the following values:
@table @samp
@item fast_bilinear
Select fast bilinear scaling algorithm.
@item bilinear
Select bilinear scaling algorithm.
@item bicubic
Select bicubic scaling algorithm.
@item experimental
Select experimental scaling algorithm.
@item neighbor
Select nearest neighbor rescaling algorithm.
@item area
Select averaging area rescaling algorithm.
@item bicublin
Select bicubic scaling algorithm for the luma component, bilinear for
chroma components.
@item gauss
Select Gaussian rescaling algorithm.
@item sinc
Select sinc rescaling algorithm.
@item lanczos
Select lanczos rescaling algorithm.
@item spline
Select natural bicubic spline rescaling algorithm.
@item print_info
Enable printing/debug logging.
@item accurate_rnd
Enable accurate rounding.
@item full_chroma_int
Enable full chroma interpolation.
@item full_chroma_inp
Select full chroma input.
@item bitexact
Enable bitexact output.
@end table
@item srcw
Set source width.
@item srch
Set source height.
@item dstw
Set destination width.
@item dsth
Set destination height.
@item src_format
Set source pixel format (must be expressed as an integer).
@item dst_format
Set destination pixel format (must be expressed as an integer).
@item src_range
Select source range.
@item dst_range
Select destination range.
@item param0, param1
Set scaling algorithm parameters. The specified values are specific of
some scaling algorithms and ignored by others. The specified values
are floating point number values.
@item sws_dither
Set the dithering algorithm. Accepts one of the following
values. Default value is @samp{auto}.
@table @samp
@item auto
automatic choice
@item none
no dithering
@item bayer
bayer dither
@item ed
error diffusion dither
@item a_dither
arithmetic dither, based using addition
@item x_dither
arithmetic dither, based using xor (more random/less apparent patterning that
a_dither).
@end table
@end table
@c man end SCALER OPTIONS