Y'UV422 , RGB888 Formats

Y'UV422 to RGB888 conversion

 http://en.wikipedia.org/wiki/YUV

Y'UV422 to RGB888 conversion

Input: Read 4 bytes of Y'UV (u, y1, v, y2 )

Output: Writes 6 bytes of RGB (R, G, B, R, G, B)

y1 = yuv[0];
u  = yuv[1];
y2 = yuv[2];
v  = yuv[3];

Using this information it could be parsed as regular Y'UV444 format to get 2 RGB pixels info:

rgb1 = Y'UV444toRGB888(y1, u, v);
rgb2 = Y'UV444toRGB888(y2, u, v);

Y'UV422 can also be expressed in YUY2 FourCC format code. That means 2 pixels will be defined in each macropixel (four bytes) treated in the image. .

Y'UV411 to RGB888 conversion

Input: Read 6 bytes of Y'UV

Output: Writes 12 bytes of RGB

// Extract YUV components
u  = yuv[0];
y1 = yuv[1];
y2 = yuv[2];
v  = yuv[3];
y3 = yuv[4];
y4 = yuv[5];

rgb1 = Y'UV444toRGB888(y1, u, v);
rgb2 = Y'UV444toRGB888(y2, u, v);
rgb3 = Y'UV444toRGB888(y3, u, v);
rgb4 = Y'UV444toRGB888(y4, u, v);

So the result is we are getting 4 RGB pixels values (4*3 bytes) from 6 bytes. This means reducing the size of transferred data to half, with a loss of quality.

Y'UV420p (and Y'V12 or YV12) to RGB888 conversion

Y'UV420p is a planar format, meaning that the Y', U, and V values are grouped together instead of interspersed. The reason for this is that by grouping the U and V values together, the image becomes much more compressible. When given an array of an image in the Y'UV420p format, all the Y' values come first, followed by all the U values, followed finally by all the V values.
The Y'V12 format is essentially the same as Y'UV420p, but it has the U and V data switched: the Y' values are followed by the V values, with the U values last. As long as care is taken to extract U and V values from the proper locations, both Y'UV420p and Y'V12 can be processed using the same algorithm.
As with most Y'UV formats, there are as many Y' values as there are pixels. Where X equals the height multiplied by the width, the first X indices in the array are Y' values that correspond to each individual pixel. However, there are only one fourth as many U and V values. The U and V values correspond to each 2 by 2 block of the image, meaning each U and V entry applies to four pixels. After the Y' values, the next X/4 indices are the U values for each 2 by 2 block, and the next X/4 indices after that are the V values that also apply to each 2 by 2 block.
Translating Y'UV420p to RGB is a more involved process compared to the previous formats. Lookup of the Y', U and V values can be done using the following method:

size.total = size.width * size.height;
y = yuv[position.y * size.width + position.x];
u = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total];
v = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total + (size.total / 4)];
rgb = Y'UV444toRGB888(y, u, v);

Here "/" is Div not division.

As shown in the above image, the Y', U and V components in Y'UV420 are encoded separately in sequential blocks. A Y' value is stored for every pixel, followed by a U value for each 2×2 square block of pixels, and finally a V value for each 2×2 block. Corresponding Y', U and V values are shown using the same color in the diagram above. Read line-by-line as a byte stream from a device, the Y' block would be found at position 0, the U block at position x×y (6×4 = 24 in this example) and the V block at position x×y + (x×y)/4 (here, 6×4 + (6×4)/4 = 30).

http://en.wikipedia.org/wiki/YCbCr
 http://www.mathworks.com/matlabcentral/fileexchange/31625-convert-rgb-to-yuv/content/convert_RGB_to_YUV.m
http://www.fourcc.org/fccyvrgb.php
http://stackoverflow.com/questions/1945374/convert-yuv-sequence-to-bmp-images

rgb = imread('board.tif');
ycbcr = rgb2ycbcr(rgb);
rgb2 = ycbcr2rgb(ycbcr);

http://amath.colorado.edu/computing/Matlab/Tutorial/ImageProcess.html

Selecting Rows and Columns of a Matrix

http://langvillea.people.cofc.edu/DISSECTION-LAB/Emmie%27sBibleCodeModule/matlabtutorial.html