[geekmaster]

(reserved for more content)

For now, here is my older dither logic that uses a dither table, but does take kindle variations into account:

PHP Code:

// global vars
u8 *fb0=NULL;   // framebuffer pointer
int fdFB=0;    // fb0 file descriptor
u32 fs=0;     // fb0 stride
u32 MX=0;    // xres (visible)
u32 MY=0;   // yres (visible)
u8 blk=0;  // black
u8 wht=0; // white
u8 pb=0; // pixel bits

//========================================
// setpx - draw pixel using ordered dither
// x,y: screen coordinates, c: color(0-64).
// (This works on all eink kindle models.)
//----------------------------------------
void inline setpx(int x,int y,int c) {
    static int dt[64] = { 1,33,9,41,3,35,11,43,49,17,57,25,51,19,59,27,13,45,5,
    37,15,47,7,39,61,29,53,21,63,31,55,23,4,36,12,44,2,34,10,42,52,20,60,28,50,
    18,58,26,16,48,8,40,14,46,6,38,64,32,56,24,62,30,54,22 }; // dither table
    fb0[pb*x/8+fs*y]=((128&(c-dt[(7&x)+8*(7&y)]))/128*(blk&(240*(1&~x)|
        15*(1&x)|fb0[pb*x/8+fs*y])))|((128&(dt[(7&x)+8*(7&y)]-c))/128*wht|
        (blk&((240*(1&x)|15*(1&~x))&fb0[pb*x/8+fs*y]))); // geekmaster formula 42
} 


I will let you meditate on that until I add more here later...