The present disclosure relates to signal processing such as image processing, signal encoding, digital watermarking and data hiding. One claim recites a method including: capturing imagery corresponding to a printed object with a red or blue illumination source, the red or blue illumination source having an illumination wavelength at or around 660 nm or an illumination wavelength in the range of 60 nm centered around 460 nm, said capturing imagery yielding captured data; wherein the printed object includes a clear coat printed thereon, the clear coat including a material that has a peak absorbance at or around 660 nm or in the range of 60 nm centered around 460 nm, the clear coat printed in a manner to convey an encoded plural-bit message, the encoded plural-bit message corresponding to product information; analyzing the captured data with one or more programmed multi-core processors to decode the encoded plural-bit message, said analyzing yielding the product information; and providing the product information as an output. Of course, other claims, technology and combinations are disclosed.