STEP_C1           823 3rdparty/libjpeg/jquant2.c     inc1 = inc1 * (2 * STEP_C1) + STEP_C1 * STEP_C1;
STEP_C1           846 3rdparty/libjpeg/jquant2.c         xx1 += 2 * STEP_C1 * STEP_C1;