convert double to 12 bit using matlab

I am trying to implement color combine function from a imaging software called metamorph in matlab.I have three uint16 bit files(R,G and B) .I need to convert them to 12 bit and then combine them into a RGB image.metamorph converts the 16-bit files to 12-bit and then creates the RGB image from the three 12-bit files.my code is as follows开发者_StackOverflow社区.I am not quite sure how to go about converting a 16-bit image file to 12-bit.

    C1 = imread('metamorph/R.tif',3);
    C2 = imread('metamorph/G.tif',3);
    C3 = imread('metamorph/B.tif',3);

    R=mat2gray(C1);
    G=mat2gray(C2);
    B=mat2gray(C3);

    rgb1=cat(3,R,G,B);
    imshow(rgb1)

any help is greatly appreciated.

Thanks

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I don't think MATLAB has a data type for 12 bit (which would be one-and-a-half byte per color per pixel). Of course you can scale you double data to fit into a 12 bit integer:

rgb12= round(rgb1/max(rgb1(:))*(2^12-1)); %# scale & round image values to 12 bit

... but then the real question is what good does that do:

• do you want to export to some 12bit RGB file format? imwrite can apparently do 12bit JPEG, but I'm unsure if that is 12 bit per color.
• or do you want to save RAM while in MATLAB? In this case I'm not sure there is a sensible way to do that.