We posted a copy of the Canon C100 owners manual on our C100 page:
Canon C100 Cinema EOS Camera 6340B002 - $6499 In Stock (http://shop.texasmediasystems.com/Canon-C100-Cinema-EOS-Camera-6340B002_p_4993.html)

Here's a direct link to the PDF 17 MB file:
http://www.texasmediasystems.com/PDFs/Canon%20C100%20Manual.pdf

Pixel Masking or "Adjusting the Black Balance" is covered on page 43.

Thank you very much! Have been waiting for this!