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@gmx.at>
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04bb26e3ee
@ -72,6 +72,7 @@ typedef struct {
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Point *point_cache;
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Point *next_cache;
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double (*zyklus)[2];
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uint32_t dither;
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} MBContext;
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#define OFFSET(x) offsetof(MBContext, x)
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@ -224,6 +225,8 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
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double zr=cr;
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double zi=ci;
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uint32_t c=0;
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double dv= mb->dither / (double)(1LL<<32);
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mb->dither= mb->dither*1664525+1013904223;
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if(color[x + y*linesize] & 0xFF000000)
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continue;
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@ -267,7 +270,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
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c= ((c<<5)&0xE0) + ((c<<16)&0xE000) + ((c<<27)&0xE00000);
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}
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}else if(mb->inner==CONVTIME){
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c= (i*255/mb->maxiter)*0x010101;
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c= floor(i*255.0/mb->maxiter+dv)*0x010101;
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} else if(mb->inner==MINCOL){
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int j;
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double closest=9999;
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@ -278,7 +281,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize,
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closest_index= j;
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}
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closest = sqrt(closest);
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c= lrintf((mb->zyklus[closest_index][0]/closest+1)*127) + lrintf((mb->zyklus[closest_index][1]/closest+1)*127)*256;
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c= lrintf((mb->zyklus[closest_index][0]/closest+1)*127+dv) + lrintf((mb->zyklus[closest_index][1]/closest+1)*127+dv)*256;
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}
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}
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c |= 0xFF000000;
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