MATLAB读取一张RGB图片转成YUV格式

转载：https://www.cnblogs.com/hythink/p/5421720.html

1.读入照片

控制输出的标志定义

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clc;close all;clear YES = 1; NO = 0; %YES表示输出该文件，请用户配置 yuv444_out_txt = 1;   yuv444_out_yuv = 0;   yuv422_out_txt = 0; yuv422_out_yuv = 0;   yuv420_out_txt = 0; yuv420_out_yuv = 1;

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filename = 'Koala.jpg'; filestr = filename(1:findstr(filename,'.jpg')-1); filepath = ['.\' filestr 'out\'] mkdir(filepath); filestr = [filepath filestr]; RGBimg =imread(filename); figure;imshow(RGBimg);

 1）读入的照片由filename 配置，这里照片必须放在该目录下。如：filename = 'Koala.jpg'

 2）filename找到字符串的起始位置。findstr('Koala.jpg','.jpg') = 6，所以就可以取到去掉后缀名的文件名

 3）得到一个 .\文件名out\的目录

 4）创建该目录

 5）filestr = 目录+文件名，用于后面的数据输出，方便输出到 .\文件名out\目录下。这里 filestr = '.\Koalaout\Koala'

2. 调用matlab函数将rgb转换成yuv

1 2	YUVimg = rgb2ycbcr(RGBimg);     %%% rgb -> yuv figure;imshow((YUVimg));

3.分别取出YUV

　　Y,U,V数据保留矩阵存储方式，方便后面的4:2:2，4:2:0采样，更加直观

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[imgHeight imgWidth imgDim] = size(YUVimg);         %% len = imgHeight*imgWidth*imgDim; yuvimout = zeros(1,len); Y = YUVimg(:,:,1);     % Y 矩阵 U = YUVimg(:,:,2);     % U 矩阵 V = YUVimg(:,:,3);     % V 矩阵 Yvec = reshape(YUVimg(:,:,1)',1,[]); % 矩阵整理成行向量 Uvec = reshape(YUVimg(:,:,2)',1,[]); Vvec = reshape(YUVimg(:,:,3)',1,[]); yuvimout(1:3:len) = Yvec; yuvimout(2:3:len) = Uvec; yuvimout(3:3:len) = Vvec;

 注意：reshape矩阵时，需要对结果做转置，保证是按行来将矩阵整理成行向量的

4.输出YUV444的数据到文件

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%% % 输出图像的yuv数据到 .txt % if yuv444_out_txt == YES     filename = [filestr '_444.txt'];     fid= fopen(filename,'w');         fprintf(fid,'%02x\n',yuvimout);     fclose(fid);     disp('yuv444_out_txt YES'); else     disp('yuv444_out_txt NO'); end

 在本例中：filename = [filestr '_444.txt'] = '.\Koalaout\Koala_444.txt'

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%% % 输出图像的yuv数据到 .yuv % 四个像素为：[Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] % % 存放的码流：[Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] % % 映射的像素: [Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] if yuv444_out_yuv == YES     filename = [filestr '_444.yuv'];     fid= fopen(filename,'wb');         fwrite(fid,yuvimout,'uint8');     fclose(fid);     disp('yuv444_out_yuv YES'); else     disp('yuv444_out_yuv NO'); end

 5.将 YUV4:4:4 转成 YUYV 4:2:2 packed

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%% % YUV4:4:4 -->> YUYV 4:2:2 % 四个像素为：[Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] % % 存放的码流：[Y0 U0] [Y1 V1] [Y2 U2] [Y3 V3] % % 映射的像素: [Y0 U0 V1] [Y1 U0 V1] [Y2 U2 V3] [Y3 U2 V3] %%% len = imgHeight*imgWidth+imgHeight*imgWidth/2+imgHeight*imgWidth/2; yuv422out = zeros(1,len); yuv422sampY = Y; yuv422sampU = U(:,1:2:size(U,2)); yuv422sampV = V(:,2:2:size(V,2)); yuv422out(1:2:len) = reshape(yuv422sampY',1,[]);  %%% 注意要转置 yuv422out(2:4:len) = reshape(yuv422sampU',1,[]); yuv422out(4:4:len) = reshape(yuv422sampV',1,[]);

 说明：

1）4:2:2模式是保留所有的Y，U,V是每间隔1列抽取抽样一个点，如代码中所示。

2）YUYV 4:2:2 packed 即像素值是 YU/YV 交替存储的模式。存放的码流：[Y0 U0] [Y1 V1] [Y2 U2] [Y3 V3]

 输出数据到文件

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%% % 输出图像的yuv422数据到 .txt % if yuv422_out_txt == YES     filename = [filestr '_422.txt'];     fid= fopen(filename,'w');         fprintf(fid,'%02x\n',yuv422out);     fclose(fid);     disp('yuv422_out_txt YES'); else     disp('yuv422_out_txt NO'); end % output yuyv422 to .yuv file if yuv422_out_yuv == YES     filename = [filestr '_422yuyv.yuv'];     fid= fopen(filename,'wb');         fwrite(fid,yuv422out,'uint8');     fclose(fid);     disp('yuv422_out_yuv YES'); else     disp('yuv422_out_yuv NO'); end

 6. 将 YUV4:4:4 转成 YV12 4:2:0 planar

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%% % YUV4:4:4 -->> YUYV 4:2:0 % output yuyv422 to .yuv file % 第一行四个像素为：[Y0 U0 V0] [Y1 U1 V1] [Y2 U2 V2] [Y3 U3 V3] % 第二行四个像素为：[Y4 U4 V4] [Y5 U5 V5] [Y6 U6 V6] [Y7 U7 V7] % 4:2:0 采样 % 第一行采样像素为：[Y0 U0   ] [Y1      ] [Y2 U2   ] [Y3      ] % 第二行采样像素为：[Y4    V4] [Y5      ] [Y6    V6] [Y7      ] % 420yv12 planar 的存储码流: [Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7] [V4 V6] [U0 U2] % 映射的像素:  [Y0 U0 V4] [Y1 U0 V4] [Y2 U2 V6] [Y3 U2 V6] %             [Y4 U0 V4] [Y5 U0 V4] [Y6 U2 V6] [Y7 U2 V6] %%% len = imgHeight*imgWidth+imgHeight*imgWidth/4+imgHeight*imgWidth/4; yuv420out = []; yuv420sampY = Y; yuv420sampU = U(1:2:size(U,1),1:2:size(U,2)); yuv420sampV = V(2:2:size(V,1),1:2:size(V,2)); %%%yuv420out = [y v u]  % yuv420 yv12 format yuv420out = [yuv420out reshape(yuv420sampY',1,[])];    %Y 注意要转置 yuv420out = [yuv420out reshape(yuv420sampV',1,[])];    %V yuv420out = [yuv420out reshape(yuv420sampU',1,[])];    %U

说明：

1）yuv420sampU = U(1:2:size(U,1),1:2:size(U,2)); 从图片的第一行开始 每间隔1行 和 每间隔1列 采样一个U

2）yuv420sampV = V(2:2:size(V,1),1:2:size(V,2)); 从图片的第二行开始 每间隔1行 和 每间隔1列 采样一个V

数据数据到文件

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%% % 输出图像的yuv422数据到 .txt % if yuv420_out_txt == YES     filename = [filestr '_420.txt'];     fid= fopen(filename,'w');         fprintf(fid,'%02x\n',yuv420out);     fclose(fid);     disp('yuv420_out_txt YES'); else     disp('yuv420_out_txt NO'); end % output yuyv420 to .yuv file if yuv420_out_yuv == YES     filename = [filestr '_420yv12.yuv'];     fid= fopen(filename,'wb');         fwrite(fid,yuv420out,'uint8');     fclose(fid);     disp('yuv420_out_yuv YES'); else     disp('yuv420_out_yuv NO'); end

 观察命令输出，并等待关闭

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disp('---program run susseed---'); disp('---press any key to close all figure---'); system('pause'); close all;

打开输出的yuv文件查看图片

参考

1	http://www.cnblogs.com/xkfz007/archive/2012/07/31/2616806.html

1	http://www.xuebuyuan.com/1541892.html

1	http://www.fourcc.org/yuv.php

 代码链接：

1	http://pan.baidu.com/s/1pLMRcmB