This disclosure relates to advanced image signal processing technology including encoded signals and digital watermarking. We disclose methods, systems and apparatus for determining which ink(s) should be selected to carry an encoded signal for a given machine-vision wavelength for a retail package or other printed design. We also disclose retail product packages and other printed objects, and methods to generate such, including a sparse mark in a first ink and an overprinted ink flood in a second ink. The first ink and the second ink are related through tack and spectral reflectance difference. Of course, other methods, packages, printed objects, systems and apparatus are described in this disclosure.