superpixels() already gives the labeled (connected components) image. https://www.mathworks.com/help/images/ref/superpixels.html?s_tid=srchtitle
Show your code where you called superpixels().
Also define what it is that you think makes a label "bad" as opposed to good. It doesn't make sense to have labels as only 0 or 1. You will have numbers up as high as the number of superpixel regions that were found. Virtually every region in there will have label numbers more than 1.
And you say "Input of the connected components algorithm must be the "Label Matrix"" Not true. Labeling and determining the connected components are the same thing. There are two functions for that - bwlabel() and bwconncomp() - and they both work off binary images. It doesn't make sense to send an already-labeled image into bwlabel() or bwconncomp() as you said. Actually the output of the connected components algorithm will be the "Label Matrix", NOT the input.
Bottom line - I don't know what you need to do. Your said your overall task is "to implement SLIC Superpixels Method" and that is done by the superpixels() function. Use it, if you haven't already. I don't know what else to answer.
