[{"data":1,"prerenderedAt":234},["ShallowReactive",2],{"tag-文件读取-1":3},{"title":4,"articles":5,"hot_article":19,"month_arch":82,"total":230,"cover":231},"文件读取 - 独孤影的博客",[6],{"id":7,"title":8,"uri":8,"author":9,"tags":10,"created_at":16,"view_count":17,"content":18},5,"bmp文件格式分析","duguying",[11,12,13,14,15],"bmp","C语言","二进制","文件读取","格式","2014-07-17 12:41:31",6180,"\u003Cp>bmp格式图片文件由4部分组成：文件头(BitmapFileHeader)，信息头(BitmapInfoHeader)，颜色表(RGBQuad)，像素矩阵(RGB)[即数据区]。\u003C\u002Fp>\u003Cp>文件头(BitmapFileHeader)\u003C\u002Fp>\u003Cpre class=\"brush: cpp;\">typedef struct _BITMAPFILEHEADER\n{\n\tBYTE2  bfType;  \u002F\u002F类型标识0x4d42\n\tBYTE4  bfSize;  \u002F\u002F文件大小(字节)\n\tBYTE2  bfReserved1;  \u002F\u002F保留1(0)\n\tBYTE2  bfReserved2;  \u002F\u002F保留2(0)\n\tBYTE4  bfOffBits;  \u002F\u002F数据区偏移(字节)\n} BitmapFileHeader;\u003C\u002Fpre>\u003Cp>信息头(BitmapInfoHeader)\u003C\u002Fp>\u003Cpre class=\"brush: cpp;\">typedef struct _BITMAPINFOHEADER{ \n\tBYTE4  biSize;  \u002F\u002F本结构的大小，根据不同的操作系统而不同，在Windows中，此字段的值总为0x28字节=40字节\n\tBYTE4  biWidth;  \u002F\u002F图片宽度(px)\n\tBYTE4  biHeight;  \u002F\u002F图片高度(px)\n\tBYTE2  biPlanes;  \u002F\u002F目标设备的级别(1)\n\tBYTE2  biBitCount;  \u002F\u002F每个像素所需的位数，必须是1(双色),4(16色)，8(256色)或24(真彩色)之一\n\tBYTE4  biCompression;  \u002F\u002F是否压缩(0不压缩)\n\tBYTE4  biSizeImage;  \u002F\u002F图像数据区大小\n\tBYTE4  biXPelsPerMeter;  \u002F\u002F水平分辨率，像素每米\n\tBYTE4  biYPelsPerMeter;  \u002F\u002F垂直分辨率，像素每米\n\tBYTE4  biClrUsed;  \u002F\u002FBMP图像使用的颜色，0表示使用全部颜色，对于256色位图来说，此值为0x100=256\n\tBYTE4  biClrImportant;  \u002F\u002F重要的颜色数，此值为0时所有颜色都重要，对于使用调色板的BMP图像来说，\n                                \u002F\u002F当显卡不能够显示所有颜色时，此值将辅助驱动程序显示颜色\n} BitmapInfoHeader;\u003C\u002Fpre>\u003Cp>颜色表(RGBQuad)\u003C\u002Fp>\u003Cpre class=\"brush: cpp;\">typedef struct _RGBQUAD {\n\tBYTE1  rgbBlue;  \u002F\u002F蓝色分量\n\tBYTE1  rgbGreen;  \u002F\u002F绿色分量\n\tBYTE1  rgbRed;  \u002F\u002F红色分量\n\tBYTE1  rgbReserved;  \u002F\u002F保留(0),非0则为alpha通道\n} RGBQuad;\u003C\u002Fpre>\u003Cp>像素\u003C\u002Fp>\u003Cpre class=\"brush: cpp;\">typedef struct _RGBPx\n{\n\tBYTE1  R;  \u002F\u002F红色分量\n\tBYTE1  G;  \u002F\u002F绿色分量\n\tBYTE1  B;  \u002F\u002F蓝色分量\n} RGBPx;\u003C\u002Fpre>\u003Cp style=\"text-align: center;\">\u003Ca href=\"\u002F\u002Fduguying.oss-cn-qingdao.aliyuncs.com\u002F2014\u002F9\u002F8\u002Fimage_matrix.png\">\u003Cimg src=\"\u002F\u002Fduguying.oss-cn-qingdao.aliyuncs.com\u002F2014\u002F9\u002F8\u002Fimage_matrix.png\" title=\"\" alt=\"image_matrix.png\"\u002F>\u003C\u002Fa>\u003C\u002Fp>\u003Cp>当图像颜色为24位时，即为全彩色RGB模式，无颜色表，所有颜色皆为重要色，因此biBitCount=24时文件中没有RGBQuad区域；若biBitCount为其他值，则图像为索引模式，颜色表中包含图像所用到的颜色，RGBQuad区域为RGBQuad结构体数组。文件中文件头(BitmapFileHeader)，信息头(BitmapInfoHeader)，颜色表(RGBQuad)三个区域之后是像素矩阵区域。\u003C\u002Fp>\u003Cp>像素矩阵区中对于24位全色彩文件是RGBQuad区域为RGBQuad结构体数组，对于索引模式图像会将颜色表按照先后顺序编号，例如4位颜色，16色，将会编号0~15号颜色，如此0000b(1)表示第1种颜色，0001b(2)，0010b(3)，0011b(4)，0100b(5)……故一字节可以表示两个像素，如0xa2=10100010b即为11号和2号色。\u003C\u002Fp>\u003Cp>关于像素矩阵中还有一个问题需要注意，那就是“4字节边界”。像素矩阵的存储是遵循4字节边界存储的，也就是说每一行像素的数据字节大小必须是4的倍数，可是实际上有些图片存储后并不能保证每行的字节数是4的倍数；如一幅1366*768的24位图像，这种图像一像素24位即3字节，则每行1366*3=4098字节，而4098%4=2，余2并不是4的倍数，此时应当在最后2字节后面补充2字节(0x0)。故，在读取时应当注意每行像素后面是否有空边界。\u003C\u002Fp>\u003Cp>最后，读取的像素还要进行倒置才能够正确的显示，因为原像素矩阵是上下颠倒，左右颠倒的。\u003C\u002Fp>\u003Cp style=\"text-align: center;\">\u003Ca href=\"\u002F\u002Fduguying.oss-cn-qingdao.aliyuncs.com\u002F2014\u002F9\u002F8\u002Fpaint_picture_reverse_demo.png\">\u003Cimg src=\"\u002F\u002Fduguying.oss-cn-qingdao.aliyuncs.com\u002F2014\u002F9\u002F8\u002Fpaint_picture_reverse_demo.png\" title=\"\" alt=\"paint_picture_reverse_demo.png\"\u002F>\u003C\u002Fa>\u003C\u002Fp>\u003Cp>最后附上我自己实现的零依赖的bmp解析项目，直接读取二进制bmp文件解析，并带有基础图像变换函数\u003Ca href=\"https:\u002F\u002Fgithub.com\u002Forganc\u002Fimage\">https:\u002F\u002Fgithub.com\u002Forganc\u002Fimage\u003C\u002Fa> 。\u003C\u002Fp>",{"title":20,"list":21},"最热文章",[22,28,34,40,46,52,58,64,70,76],{"id":23,"title":24,"uri":25,"author":9,"created_at":26,"view_count":27},28,"docker容器目录与主机目录同步","\u002Farticle\u002Fdocker容器目录与主机目录同步","2014-12-31 12:34:08",15570,{"id":29,"title":30,"uri":31,"author":9,"created_at":32,"view_count":33},21,"beego中使用fis","\u002Farticle\u002Fbeego中使用fis","2014-12-03 10:47:56",9250,{"id":35,"title":36,"uri":37,"author":9,"created_at":38,"view_count":39},20,"用github登录，oauth开发","\u002Farticle\u002F用github登录，oauth开发","2014-11-23 13:33:37",9113,{"id":41,"title":42,"uri":43,"author":9,"created_at":44,"view_count":45},18,"windows服务注册工具nssm","\u002Farticle\u002Fwindows服务注册工具nssm","2014-10-31 21:34:39",9047,{"id":47,"title":48,"uri":49,"author":9,"created_at":50,"view_count":51},49,"用latex排版中文书籍","\u002Farticle\u002F用latex排版中文书籍","2016-10-31 11:12:02",8634,{"id":53,"title":54,"uri":55,"author":9,"created_at":56,"view_count":57},19,"texlive中文书签乱码","\u002Farticle\u002Ftexlive中文书签乱码","2014-11-15 02:54:01",8461,{"id":59,"title":60,"uri":61,"author":9,"created_at":62,"view_count":63},6,"Windows上的软件包管理器chocolatey","\u002Farticle\u002FWindows上的软件包管理器chocolatey","2014-08-10 15:55:22",8009,{"id":65,"title":66,"uri":67,"author":9,"created_at":68,"view_count":69},3,"利用开源和免费资源搭建CI环境","\u002Farticle\u002F利用开源和免费资源搭建CI环境","2014-07-04 16:54:58",7732,{"id":71,"title":72,"uri":73,"author":9,"created_at":74,"view_count":75},16,"php-fpm网站目录权限配置","\u002Farticle\u002Fphp-fpm网站目录权限配置","2014-10-18 01:36:10",7274,{"id":77,"title":78,"uri":79,"author":9,"created_at":80,"view_count":81},27,"sublime text 2插件开发，外部修改文件无法重新加载","\u002Farticle\u002Fsublime text 2插件开发，外部修改文件无法重新加载","2014-12-26 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