Bayer格式转RGB的代码，好像是来自于v4l

/*
bayer第一行
adjacent_bayer第二行
*/
static void convert_border_bayer_line_to_bgr24(const unsigned char *bayer, const unsigned char *adjacent_bayer,
                                               unsigned char *bgr, int width, int start_with_green, int blue_line)
{
    int t0, t1;

    if (start_with_green)
    {
        /* First pixel */
        if (blue_line)
        {
            *bgr++ = bayer[1];
            *bgr++ = bayer[0];
            *bgr++ = adjacent_bayer[0];
        } else {
            *bgr++ = adjacent_bayer[0];
            *bgr++ = bayer[0];
            *bgr++ = bayer[1];
        }
        /* Second pixel */
        t0 = (bayer[0] + bayer[2] + adjacent_bayer[1] + 1) / 3;
        t1 = (adjacent_bayer[0] + adjacent_bayer[2] + 1) >> 1;
        if (blue_line)
        {
            *bgr++ = bayer[1];
            *bgr++ = t0;
            *bgr++ = t1;
        }
        else
        {
            *bgr++ = t1;
            *bgr++ = t0;
            *bgr++ = bayer[1];
        }
        bayer++;
        adjacent_bayer++;
        width -= 2;
    }
    else
    {
        /* First pixel */
        t0 = (bayer[1] + adjacent_bayer[0] + 1) >> 1;
        if (blue_line)
        {
            *bgr++ = bayer[0];
            *bgr++ = t0;
            *bgr++ = adjacent_bayer[1];
        }
        else
        {
            *bgr++ = adjacent_bayer[1];
            *bgr++ = t0;
            *bgr++ = bayer[0];
        }
        width--;
    }

    if (blue_line)
    {
        for ( ; width > 2; width -= 2)
        {
            t0 = (bayer[0] + bayer[2] + 1) >> 1;
            *bgr++ = t0;
            *bgr++ = bayer[1];
            *bgr++ = adjacent_bayer[1];
            bayer++;
            adjacent_bayer++;

            t0 = (bayer[0] + bayer[2] + adjacent_bayer[1] + 1) / 3;
            t1 = (adjacent_bayer[0] + adjacent_bayer[2] + 1) >> 1;
            *bgr++ = bayer[1];
            *bgr++ = t0;
            *bgr++ = t1;
            bayer++;
            adjacent_bayer++;
        }
    }
    else
    {
        for ( ; width > 2; width -= 2)
        {
            t0 = (bayer[0] + bayer[2] + 1) >> 1;
            *bgr++ = adjacent_bayer[1];
            *bgr++ = bayer[1];
            *bgr++ = t0;
            bayer++;
            adjacent_bayer++;

            t0 = (bayer[0] + bayer[2] + adjacent_bayer[1] + 1) / 3;
            t1 = (adjacent_bayer[0] + adjacent_bayer[2] + 1) >> 1;
            *bgr++ = t1;
            *bgr++ = t0;
            *bgr++ = bayer[1];
            bayer++;
            adjacent_bayer++;
        }
    }

    if (width == 2)
    {
        /* Second to last pixel */
        t0 = (bayer[0] + bayer[2] + 1) >> 1;
        if (blue_line) {
            *bgr++ = t0;
            *bgr++ = bayer[1];
            *bgr++ = adjacent_bayer[1];
        }
        else
        {
            *bgr++ = adjacent_bayer[1];
            *bgr++ = bayer[1];
            *bgr++ = t0;
        }
        /* Last pixel */
        t0 = (bayer[1] + adjacent_bayer[2] + 1) >> 1;
        if (blue_line) {
            *bgr++ = bayer[2];
            *bgr++ = t0;
            *bgr++ = adjacent_bayer[1];
        }
        else
        {
            *bgr++ = adjacent_bayer[1];
            *bgr++ = t0;
            *bgr++ = bayer[2];
        }
    }
    else
    {
        /* Last pixel */
        if (blue_line) {
            *bgr++ = bayer[0];
            *bgr++ = bayer[1];
            *bgr++ = adjacent_bayer[1];
        }
        else
        {
            *bgr++ = adjacent_bayer[1];
            *bgr++ = bayer[1];
            *bgr++ = bayer[0];
        }
    }
}

void ConvertBayer2RGB24(const unsigned char *bayer,  unsigned char *bgr,
                        int width, int height,int start_with_green, int blue_line)
{
    /* render the first line */
    convert_border_bayer_line_to_bgr24(bayer, bayer + width, bgr, width,
                                       start_with_green, blue_line);
    bgr += width * 3;


    /* reduce height by 2 because of the special case top/bottom line */
    for (height -= 2; height; height--)
    {
        int t0, t1;
        /* (width - 2) because of the border */
        const unsigned char *bayer_end = bayer + (width - 2);

        if (start_with_green)
        {
            /* OpenCV has a bug in the next line, which was
               t0 = (bayer[0] + bayer[width * 2] + 1) >> 1; */
            t0 = (bayer[1] + bayer[width * 2 + 1] + 1) >> 1;
            /* Write first pixel */
            t1 = (bayer[0] + bayer[width * 2] + bayer[width + 1] + 1) / 3;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = t1;
                *bgr++ = bayer[width];
            }
            else
            {
                *bgr++ = bayer[width];
                *bgr++ = t1;
                *bgr++ = t0;
            }

            /* Write second pixel */
            t1 = (bayer[width] + bayer[width + 2] + 1) >> 1;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = bayer[width + 1];
                *bgr++ = t1;
            }
            else
            {
                *bgr++ = t1;
                *bgr++ = bayer[width + 1];
                *bgr++ = t0;
            }
            bayer++;
        }
        else
        {
            /* Write first pixel */
            t0 = (bayer[0] + bayer[width * 2] + 1) >> 1;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = bayer[width];
                *bgr++ = bayer[width + 1];
            }
            else
            {
                *bgr++ = bayer[width + 1];
                *bgr++ = bayer[width];
                *bgr++ = t0;
            }
        }

        if (blue_line)
        {
            for (; bayer <= bayer_end - 2; bayer += 2)
            {
                t0 = (bayer[0] + bayer[2] + bayer[width * 2] +
                        bayer[width * 2 + 2] + 2) >> 2;
                t1 = (bayer[1] + bayer[width] + bayer[width + 2] +
                        bayer[width * 2 + 1] + 2) >> 2;
                *bgr++ = t0;
                *bgr++ = t1;
                *bgr++ = bayer[width + 1];

                t0 = (bayer[2] + bayer[width * 2 + 2] + 1) >> 1;
                t1 = (bayer[width + 1] + bayer[width + 3] + 1) >> 1;
                *bgr++ = t0;
                *bgr++ = bayer[width + 2];
                *bgr++ = t1;
            }
        }
        else
        {
            for (; bayer <= bayer_end - 2; bayer += 2)
            {
                t0 = (bayer[0] + bayer[2] + bayer[width * 2] +
                        bayer[width * 2 + 2] + 2) >> 2;
                t1 = (bayer[1] + bayer[width] + bayer[width + 2] +
                        bayer[width * 2 + 1] + 2) >> 2;
                *bgr++ = bayer[width + 1];
                *bgr++ = t1;
                *bgr++ = t0;

                t0 = (bayer[2] + bayer[width * 2 + 2] + 1) >> 1;
                t1 = (bayer[width + 1] + bayer[width + 3] + 1) >> 1;
                *bgr++ = t1;
                *bgr++ = bayer[width + 2];
                *bgr++ = t0;
            }
        }

        if (bayer < bayer_end)
        {
            /* write second to last pixel */
            t0 = (bayer[0] + bayer[2] + bayer[width * 2] +
                    bayer[width * 2 + 2] + 2) >> 2;
            t1 = (bayer[1] + bayer[width] + bayer[width + 2] +
                    bayer[width * 2 + 1] + 2) >> 2;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = t1;
                *bgr++ = bayer[width + 1];
            }
            else
            {
                *bgr++ = bayer[width + 1];
                *bgr++ = t1;
                *bgr++ = t0;
            }
            /* write last pixel */
            t0 = (bayer[2] + bayer[width * 2 + 2] + 1) >> 1;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = bayer[width + 2];
                *bgr++ = bayer[width + 1];
            }
            else
            {
                *bgr++ = bayer[width + 1];
                *bgr++ = bayer[width + 2];
                *bgr++ = t0;
            }
            bayer++;
        }
        else
        {
            /* write last pixel */
            t0 = (bayer[0] + bayer[width * 2] + 1) >> 1;
            t1 = (bayer[1] + bayer[width * 2 + 1] + bayer[width] + 1) / 3;
            if (blue_line)
            {
                *bgr++ = t0;
                *bgr++ = t1;
                *bgr++ = bayer[width + 1];
            }
            else
            {
                *bgr++ = bayer[width + 1];
                *bgr++ = t1;
                *bgr++ = t0;
            }
        }

        /* skip 2 border pixels */
        bayer += 2;

        blue_line = !blue_line;
        start_with_green = !start_with_green;
    }

    /* render the last line */
    convert_border_bayer_line_to_bgr24(bayer + width, bayer, bgr, width,
                                       !start_with_green, !blue_line);
}

两个关键参数start_with_green和blue_line,我用的BayerBG格式start_with_green=0，blue_line=0。