image type after an ifft reconstruction I reconstruct images from MRI k-space using ifft and root-sum-of-squares method. 

imRef = ifftshift(ifftshift(ifft(ifft( ifftshift(ifftshift( kspacedata,1),2),[],1),[],2),1),2); 
imSOS    = squeeze(sqrt(sum( abs(angle(imRef)).^2, 3))); 
imagesc(abs(imSOS))

k = abs(imSOS); 
disp(class(k)); %double


Class of image matrix k is shown as double. 

Is the image matrix k an indexed image or intensity image?

The sample values from reconstructed image k is shown below. 

4.2753    4.9807    4.5435    5.6548    6.1303    5.0229
3.3805    4.6260    5.1594    5.2692    4.1187    4.4885
5.8990    5.5275    4.3493    5.6182    6.7237    4.3071
6.4885    4.6861    4.4086    3.5034    5.2378    4.7466
6.1099    4.6995    4.1673    4.7408    3.8915    5.7531
5.4006    3.1289    5.6541    5.8782    4.6568    3.8166


By referrring http://in.mathworks.com/help/matlab/creating_plots/image-types.html,
I learned that for indexed images, the data matrix is represented by integers which are indices to color map. And if it were intensity images, I feel the data range is somewhere between 0 and 1. If k represents an indexed image, how can I know the colormap associated with it?

Thanks.
FFT and IFFT are linear operators, and as such, the results only make a lot of sense in a linear intensity space, not if indexed into a non-linearly mapped space.