HIST_MIN_INDEX
offset[c] = ctrls->hist_minmax[c][HIST_MIN_INDEX];
ctrls->hist_minmax[c][HIST_MIN_INDEX] + 1);
ctrls->hist_minmax[hist_id][HIST_MIN_INDEX] = min;
offset[c] = ctrls->hist_minmax[c][HIST_MIN_INDEX];
ctrls->hist_minmax[c][HIST_MIN_INDEX] + 1);
ctrls->hist_minmax[hist_id][HIST_MIN_INDEX] = min;