Popis

PopisBarns grand tetons YCbCr separation.jpg	English: This takes an image (Image:Barns grand tetons.jpg) and displays the Y, Cb and Cr elements of it. Note that the Y image is essentailly a greyscale copy of the main image; that the white snow is represented as a middle value in both Cb and Cr; that the brown barn is represented by strong Cb and strong Cr; that the green grass is represented by strong Cb and weak Cr; and that the blue sky is represented by weak Cb and weak Cr. The murkiness of the Cb and Cr elements (to the human eye) demonstrate why many image compression codecs downsample colour; details in Y are much more visible than in Cb or Cr.
Datum	26. prosince 2006 (upload date)
Zdroj	Based on the (public domain) photo Image:Barns grand tetons.jpg. Code above and resulting output by Mike1024.
Autor	Mike1024
Svolení (Užití tohoto souboru)	Public domainPublic domainfalsefalse Já, autor tohoto díla, jej tímto uvolňuji jako volné dílo, a to celosvětově. V některých zemích to není podle zákona možné; v takovém případě: Poskytuji komukoli právo užívat toto dílo za libovolným účelem, a to bezpodmínečně s výjimkou podmínek vyžadovaných zákonem.

Generator code

In MATLAB:

RGBimage = imread('barns_grand_tetons.jpg');
[height,width,depth]=size(RGBimage);
YCbCrimage=RGB2YCbCr(RGBimage); % If you don't have the right version/toolkit this function 
                                % might not be availiable. Luckily, it's easy to implement 
                                % ourselves. Drop me (Mike1024) a message and I'll send you 
                                % my code to do it.

% Newer versions of matlab need outputimage=zeros(height*4,width,depth,'uint8');
outputimage=uint8(zeros(height*4,width,depth));
for w=1:width,
  for h=1:height,
    outputimage(h,w,1) = YCbCrimage(h,w,1); %Copy Y, Cb and Cr for normal image
    outputimage(h,w,2) = YCbCrimage(h,w,2);
    outputimage(h,w,3) = YCbCrimage(h,w,3);
    outputimage(h+height,w,1) = YCbCrimage(h,w,1); %Copy Y only for first component
    outputimage(h+height,w,2) = 128;
    outputimage(h+height,w,3) = 128;
    outputimage(h+(2*height),w,2) = YCbCrimage(h,w,2); %Cb only for second component
    outputimage(h+(2*height),w,1) = 128;
    outputimage(h+(2*height),w,3) = 128;
    outputimage(h+(3*height),w,3) = YCbCrimage(h,w,3); %Cr only for third component
    outputimage(h+(3*height),w,1) = 128;
    outputimage(h+(3*height),w,2) = 128;
  end
end

image(YCbCr2RGB(outputimage));
imwrite(YCbCr2RGB(outputimage),'YCbCr_separation.jpg','jpeg');