progress_log("read %d screenshots.",npages);
}
+static double find_aa_density(const RgbImage *ri, Point p, long background,
+ long foreground, int fg_extra) {
+ Rgb here= ri_rgb(ri, p.x, p.y);
+
+ double alpha[3], alpha_mean=0;
+ int i;
+ for (i=0; i<3; i++) {
+ unsigned char here_chan= here >> (i*8);
+ unsigned char bg_chan= background >> (i*8);
+ unsigned char fg_chan= foreground >> (i*8);
+ double alpha_chan=
+ ((double)here_chan - (double)bg_chan) /
+ ((fg_chan + fg_extra) - (double)bg_chan);
+ alpha[i]= alpha_chan;
+ alpha_mean += alpha_chan * (1/3.0);
+ }
+
+ double thresh= 1.5/AAMAXVAL;
+ double alpha_min= alpha_mean - thresh;
+ double alpha_max= alpha_mean + thresh;
+ for (i=0; i<3; i++)
+ MUST( alpha_min <= alpha[i] && alpha[i] <= alpha_max,
+ MRGB(here);MRGB(background);MRGB(foreground);MI(fg_extra);
+ MF(alpha_min); MI(i);MF(alpha[i]);MF(alpha_max) );
+
+ MUST( 0 <= alpha_mean &&
+ (fg_extra ? alpha_mean < 0.999 : alpha_mean >= 1.0),
+ MRGB(here);MRGB(background);MRGB(foreground);MI(fg_extra);
+ MF(alpha_mean); MF(alpha[0]);MF(alpha[1]);MF(alpha[2]); );
+
+ return alpha_mean;
+}
+
static void find_commodity(int offset, Rect *rr) {
/* rr->tl.x==-1 if offset out of range */
rr->tl.y= commbasey - offset*comminty;
int monochrome= 1;
FOR_P_RECT(p,*cell) {
- Rgb here= ri_rgb(ri, p.x, p.y);
- double alpha[3], alpha_mean=0;
- int i;
- for (i=0; i<3; i++) {
- unsigned char here_chan= here >> (i*8);
- unsigned char bg_chan= background >> (i*8);
- unsigned char fg_chan= foreground >> (i*8);
- double alpha_chan=
- ((double)here_chan - (double)bg_chan) /
- ((fg_chan + fg_extra) - (double)bg_chan);
- alpha[i]= alpha_chan;
- alpha_mean += alpha_chan * (1/3.0);
- }
+ double alpha= find_aa_density(ri,p,background,foreground,fg_extra);
- double thresh= 1.5/AAMAXVAL;
- double alpha_min= alpha_mean - thresh;
- double alpha_max= alpha_mean + thresh;
- for (i=0; i<3; i++)
- MUST( alpha_min <= alpha[i] && alpha[i] <= alpha_max,
- MI(i);MRGB(here);MRGB(background);MRGB(foreground);
- MF(alpha_min);MF(alpha[i]);MF(alpha_max) );
-
- MUST( 0 <= alpha_mean && alpha_mean < 0.999,
- MRGB(here);MRGB(background);MRGB(foreground);
- MF(alpha_mean); MF(alpha[0]);MF(alpha[1]);MF(alpha[2]); );
- int here_int= floor((AAMAXVAL+1)*alpha_mean);
+ int here_int= floor((AAMAXVAL+1)*alpha);
assert(here_int <= AAMAXVAL);
if (!(here_int==0 || here_int==AAMAXVAL)) monochrome=0;
cim->d[p.y * cim->w + p.x]= '0' + here_int;