Why is my image not recombining properly after a DCT?

I am doing some image processing and have found that my code does not quite work, the image will not recombine properly after a DCT is applied. The relevant part of the code is below:

    %Clear command window.
clc;
    %Clear workspace.
clear;

    %Load the image file, change to Lena, Airplane, or any other 512x512 file.
RGB = imread ('Lena.tiff'); 
    %Display the result of the conversion.
figure, imshow(RGB), title('Original Image')

    %Convert RGB image to YCbCr Components.
YCbCr = rgb2ycbcr(RGB);
    %Isolate Y. 
Y = YCbCr(:,:,1);
    %Isolate Cb. 
Cb = YCbCr(:,:,2);
    %Isolate Cr. 
Cr= YCbCr(:,:,3);

    %Perform a 2D DCT operation on Y, Cb, and Cr, in blocks of 8x8 pixels.
YDCT = blkproc(Y,[8 8],@dct2);
CbDCT = blkproc(Cb,[8 8],@dct2);
CrDCT = blkproc(Cr,[8 8],@dct2);

    %Perform an inverse DCT operation.
IDCTY = blkproc(YDCT,[8 8],@idct2);
IDCTCb = blkproc(CbDCT,[8 8],@idct2);
IDCTCr = blkproc(CrDCT,[8 8],@idct2);

    %Recombine the YCbCr components.  
Recombined = cat(3, IDCTY, IDCTCb, IDCTCr);
    %Convert the recombined YCbCr matrix to RGB.
RecombinedIMG = ycbcr2rgb(Recombined);
    %Display the recombined image.
figure, imshow(RecombinedIMG), title('Recombined')

Answer 1

[Ryan Brewes]

imread reads the original Image as a 512x512x3 uint8.

Both dct2 and idct2 produce a 512x512x3 double.

To display the image correctly, convert back uint8, for example by changing:

IDCTY = blkproc(YDCT,[8 8],@idct2);
IDCTCb = blkproc(CbDCT,[8 8],@idct2);
IDCTCr = blkproc(CrDCT,[8 8],@idct2);

to:

IDCTY = uint8(blkproc(YDCT,[8 8],@idct2));
IDCTCb = uint8(blkproc(CbDCT,[8 8],@idct2));
IDCTCr = uint8(blkproc(CrDCT,[8 8],@idct2));

Answer 2

[Alexander De-Ville]

No one?