Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

Systems and methods for adding data to a printed publication are provided. One method includes receiving variable data and controlling an energy source to at least partially ablate the printed publication based on the variable data. The printed publication is printed on the substrate using the commercial printing press based on fixed data. Controlling the energy source to at least partially ablate the printed publication includes, after the printed publication has been printed on the substrate by the commercial printing press based on the fixed data, controlling the energy source to remove a portion of the printed publication based on the variable data.