Direct imaging in theory and practice - Computer to press vs. computer to print

Since 1993 computer to ... - technologies are spreading into the market. Powerful computer to film and computer to plate equipment are offered and in use. The most fascinating technology is to use the digital data file for the total page to be printed directly into the press, that means computer to press or computer to print technologies. Using computer to press, the plate is imaged within the press, no stand-alone computer to plate equipment is needed. In comparison there are computer to print equipment which work without a job-specific printing form, examples for this are the E-Print 1000 from Indigo and the DCP-1 digital printing press from Xeikon. The new generation of computer to press equipment, the Quickmaster DI from Heidelberg using Direct Imaging technology, is described in detail as a complete system solution. Computer to press and computer to print equipment is explained from a technical point of view with a strong user orientation. Technical concepts, imaging systems, used materials, print quality, life time and the advantages and limitation of existing digital printing systems are described. In addition, newly announced computer to print equipment are explained, for example equipment from Scitex, Mitsubishi and Delphax for multicolor, high speed printing. A third possibility in computer to press technology is the concept of using rewriteable printing surfaces, as sometimes before described in the patent literature and several conferences. The announced systems from MAN Poland DICOweb Lithe and DICOweb Gravure - as well as the NIPSON technology called Magnetolithography are discussed. In a summarized comparison the advantages and the expected market segments of all the different computer to press technologies are given. All in all, this paper deals with technologies which are already in the market or have been announced to be available in the near future. Special attention is paid to the total workflow for digital print production, requirements, changes and challenges are mentioned.