yuv二值化操作

UV是色差分量，UV爲0就會全是綠色，全爲0x80的時候才能看到灰度圖。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

int show_hex(char* begin, int len)
{
    int i = 0;
    for (i = 0; i < len; i++)
    {
        printf("%02x ", begin[i]);
    }
    printf("\n");

    return 0;
}

int write_file(const char* path, char* buffer, int len)
{
    FILE* fp = fopen(path, "w+");
    assert(fp);
    int ret = fwrite(buffer, 1, len, fp);
    assert(ret == len);
    fclose(fp);

    return 0;
}

int cover(char* dst, int d_width, int d_height, int x, int y, char* src, int s_width, int s_height)
{
    int i = 0;
    int j = 0;

    for (i = 0; i < s_height; i++)
    {
        int idx = x*d_width + y;
        for (j = 0; j < s_width; j++)
        {
            dst[idx++] = src[i*s_width+j];
        }
        x++;
    }

    return 0;
}

int main()
{
    int width = 1280;
    int height = 720;
    int size = width*height*1.5;
    char* buffer = (char*)malloc(size);
    assert(buffer);
    memset(buffer, 0x80, size);// uv 需設置爲0x80
    memset(buffer, 0xff, width*height); // 設置Y 爲0xff(白色)

    char tmp[16*16];
    memset(tmp, 0, 16*16); // 設置cover 爲0(黑色)
    cover(buffer, width, height, 0, 0, tmp, 16, 16);

    write_file("test.yuv", buffer, size);
    free(buffer);

    return 0;
}