[FFmpeg-cvslog] mandelbrot: add dither to convergence & mincol colorings.
Michael Niedermayer
git at videolan.org
Tue Nov 15 23:01:05 CET 2011
ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Tue Nov 15 21:33:11 2011 +0100| [04bb26e3ee50a3506af924ff83bf83e13ebef9b0] | committer: Michael Niedermayer
mandelbrot: add dither to convergence & mincol colorings.
This avoids banding artifacts.
Note, low end TFTs still show some banding.
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=04bb26e3ee50a3506af924ff83bf83e13ebef9b0
---
libavfilter/vsrc_mandelbrot.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/libavfilter/vsrc_mandelbrot.c b/libavfilter/vsrc_mandelbrot.c
index f575fb1..194d866 100644
--- a/libavfilter/vsrc_mandelbrot.c
+++ b/libavfilter/vsrc_mandelbrot.c
@@ -72,6 +72,7 @@ typedef struct {
Point *point_cache;
Point *next_cache;
double (*zyklus)[2];
+ uint32_t dither;
} MBContext;
#define OFFSET(x) offsetof(MBContext, x)
@@ -224,6 +225,8 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
double zr=cr;
double zi=ci;
uint32_t c=0;
+ double dv= mb->dither / (double)(1LL<<32);
+ mb->dither= mb->dither*1664525+1013904223;
if(color[x + y*linesize] & 0xFF000000)
continue;
@@ -267,7 +270,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
c= ((c<<5)&0xE0) + ((c<<16)&0xE000) + ((c<<27)&0xE00000);
}
}else if(mb->inner==CONVTIME){
- c= (i*255/mb->maxiter)*0x010101;
+ c= floor(i*255.0/mb->maxiter+dv)*0x010101;
} else if(mb->inner==MINCOL){
int j;
double closest=9999;
@@ -278,7 +281,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
closest_index= j;
}
closest = sqrt(closest);
- c= lrintf((mb->zyklus[closest_index][0]/closest+1)*127) + lrintf((mb->zyklus[closest_index][1]/closest+1)*127)*256;
+ c= lrintf((mb->zyklus[closest_index][0]/closest+1)*127+dv) + lrintf((mb->zyklus[closest_index][1]/closest+1)*127+dv)*256;
}
}
c |= 0xFF000000;
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