An imaging system may output embedded data in an output frame. Selected bits of pixel data words, corresponding to data read out from imaging pixels and non-imaging pixels, may be modified to correspond to bits of embedded data. Modifying pixel data words may include receiving a pixel data word and decatenating the pixel data words into fragments of the data word. A first fragment may correspond to bits of the data word that are replaced by embedded data bits output from an embedded data engine. A second fragment may be modified using arithmetic circuitry based on whether the embedded data bits that replace the first fragment are the same as bits of the first fragment. An output data word may be produced that includes embedded data bits at its least significant bits, most significant bits, or intermediate bits.