l01_0 = l11_0 = l21_0 = 127; l02_0 = l12_0 = l22_0 = 127; minmax_0 = l02_0; maxmin_0 = l22_0; for (i = 0; i < cols; i++) { l00_0 = *line0++; l10_0 = *line1++; l20_0 = *line2++; // sort l00_0, l10_0, l20_0 l20_1 = l20_0; l10_1 = l10_0; if (l20_0 > l10_0) { l10_1 = l20_0; l20_1 = l10_0; } // swap l00_1 = l00_0; l10_2 = l10_1; if (l10_1 > l00_0) { l00_1 = l10_1; l10_2 = l00_0; } // swap l20_2 = l20_1; l10_3 = l10_2; if (l20_1 > l10_2) { l10_3 = l20_1; l20_2 = l10_2; } // swap if (l01_0 < minmax_0) minmax_0 = l01_0; /* Compute min of max */ if (l00_1 < minmax_0) minmax_0 = l00_1; if (l21_0 > maxmin_0) maxmin_0 = l21_0; /* Comput max of min */ if (l20_2 > maxmin_0) maxmin_0 = l20_2; // sort l10 l11 l12 t0_1 = l10_3; /* Compute median of median */ t1_1 = l11_0; if (l10_3 > l11_0) { t0_1 = l11_0; t1_1 = l10_3; } t1_2 = t1_1; if (t1_1 > l12_0) { t1_2 = l12_0; } medmed_0 = t1_2; if (t0_1 > t1_2) { medmed_0 = t0_1; } // swap // minmax, medmed, maxmin medmed_1 = medmed_0; minmax_1 = minmax_0; if (minmax_0 > medmed_0) { medmed_1 = minmax_0; minmax_1 = medmed_0; } medmed_2 = medmed_1; if (medmed_1 > maxmin_0) { medmed_2 = maxmin_0; } medmed_3 = medmed_2; if (minmax_1 > medmed_2) { medmed_3 = minmax_1; } /* Move data along by one column */ minmax_0 = l01_0; l12_0 = l11_0; maxmin_0 = l21_0; l01_0 = l00_1; l11_0 = l10_3; l21_0 = l20_2; *out_data++ = medmed_3; } }

这段代码是用于图像处理中的中值滤波器，它的作用是去除噪声并平滑图像。在这段代码中，它对图像的每一列进行处理，首先将当前像素点的上下三个像素点按大小排序，然后取中间值作为当前像素点的值。接着，根据当前像素点左侧的像素点和右侧的像素点的大小关系，计算出当前像素点的值与其左侧像素点和右侧像素点的最大值和最小值，最后将处理后的像素点值存储到输出数据中。