Research On Quality Control Theory And Technology In Digital Proofing

Today's publication and printing technology has been greatly changing from the traditional analog or mixed analog-to-digital technology to all-digital production process. With color management, digital proofing has become an important component of the all-digital printing workflow. In this thesis, the basic principles and quality control techniques of color management and digital proofing are set forth and discussed. Research work is carried out on the general proofing quality control and spot color proofing program. The main research work has the following aspects:(1) The quality control mechanism for digital proofing based on ICC standard has been built in surveying and mapping industry for the first time, so the color consistency platform can be followed by the departments in the mapping units.(2) The key technologies and the present questions are analyzed and discussed in-depth. Effective ways of controlling the quality of digital proofing in all stages are employed during practice. A new basic linearization method of matching printing standard ink densities and the converse way of obtaining press ICC profile are proposed at the first time, and have been proved by the practice. The average color difference between the proof and press is near 1 NBS, which achieved a perfect color matching.(3) Using Heidelberg prepress digital proofing system and EFI XF digital proofing software environment respectively, spot color proofing was achieved to reduce the average color difference greatly. Two methods were introduced, one is CMYK values correction and the other L*a*b* values approaching. With satisfaction, the eventual average color difference for spot-color digital proofing is near 1 NBS. Based on the spot color proofing practice, a spot-color conversion algorithm for proofing was set up in a specific environment.(4) A mini print color control bar was designed and based on this a feedback mechanism was set up to trace the printing characteristics continually. So, the digital proofing environment could be updated near real time.(5) ICC profiles of presses were analyzed to approve the feasibility of establishing a standard press ICC profile, and a specific implementation plan was proposed. (6) Evaluating methods were put forward and used for the digital proofing stages and the final proof. According the present printing and measuring conditions, evaluation grading was set for discussion.