struct QuantizedValue *FindQNode(struct QuantizedValue const *q, int32 code) { if (! (q->Children[0])) if (code==q->value) return (struct QuantizedValue *) q; else return 0; else { struct QuantizedValue *found=FindQNode(q->Children[0],code); if (! found) found=FindQNode(q->Children[1],code); return found; } }
void ColorQuantize(uint8 const *Image, int Width, int Height, int flags, int ncolors, uint8 *out_pixels, uint8 *out_palette, int firstcolor) { int Error[MAX_QUANTIZE_IMAGE_WIDTH+1][3][2]; struct Sample *s=AllocSamples(Width*Height,N_DIMENSIONS); int x,y,c; for(y=0;y<Height;y++) for(x=0;x<Width;x++) { for(c=0;c<3;c++) NthSample(s,y*Width+x,N_DIMENSIONS)->Value[c]=PIXEL(x,y,c); // now, let's generate extra values to quantize on for(int i=0;i<N_EXTRAVALUES;i++) { int val1=0; for(c=0;c<3;c++) val1+=PIXEL(x,y,c)*ExtraValueXForms[i*3+c]; val1>>=8; NthSample(s,y*Width+x,N_DIMENSIONS)->Value[c]=(uint8) (MIN(255,MAX(0,val1))); } } struct QuantizedValue *q=Quantize(s,Width*Height,N_DIMENSIONS, ncolors,Weights,firstcolor); delete[] s; memset(out_palette,0x55,768); for(int p=0;p<256;p++) { struct QuantizedValue *v=FindQNode(q,p); if (v) for(int c=0;c<3;c++) out_palette[p*3+c]=v->Mean[c]; } memset(Error,0,sizeof(Error)); for(y=0;y<Height;y++) { int ErrorUse=y & 1; int ErrorUpdate=ErrorUse^1; for(x=0;x<Width;x++) { uint8 samp[3]; for(c=0;c<3;c++) { int tryc=PIXEL(x,y,c); if (! (flags & QUANTFLAGS_NODITHER)) { tryc+=Error[x][c][ErrorUse]; Error[x][c][ErrorUse]=0; } samp[c]=(uint8) MIN(255,MAX(0,tryc)); } struct QuantizedValue *f=FindMatch(samp,3,Weights,q); out_pixels[Width*y+x]=(uint8) (f->value); if (! (flags & QUANTFLAGS_NODITHER)) for(int i=0;i<3;i++) { int newerr=samp[i]-f->Mean[i]; int orthog_error=(newerr*3)/8; Error[x+1][i][ErrorUse]+=orthog_error; Error[x][i][ErrorUpdate]=orthog_error; Error[x+1][i][ErrorUpdate]=newerr-2*orthog_error; } } } if (q) FreeQuantization(q); }