Analysis of Print Attributes of Amplitude Modulated (AM) vs. Frequency Modulated (FM) Screening of Multicolor Offset Printing

  • H. Naik Dharavath (University of Wisconsin–Stout)
  • Ted M. Bensen (University of Wisconsin–Stout)
  • Bhaskar Gaddam (University of Wisconsin–Stout)


This research utilized an experimental research method. The purpose of this research study was to determine the significant differences that exist in the measurable print attributes (Print Contrast and Dot Gain) of AM vs. FM screening of multicolor offset printing. The experiment was conducted in film-based workflow. The GATF 11” x 17” Digital Four Color Test target was output by using Scitex AM and FM screening technologies. Due to excessive Tone Value Increase (TVI) during the platemaking process, the film output was adjusted to achieve linear plates. A pilot test was conducted to achieve the target ink density values (+/- 0.10) according to GRACoL standards. During the pilot test, 1,000 sheets were printed. Once the density values were achieved according to the standard ink density (SID) values, the press was run continuously without operator interference and another 1,000 sheets were printed, from which a total of 278 sheets were randomly selected for the densitometric analysis. Only the attributes of dot gain and print contrast were used to compare the two screening technologies, as they were the two attributes that measured patches made up of dots or screened tint percentages. Print attributes that utilize solid ink patches only were not compared, as one could expect similar results from both screening technologies. The findings of this study represent specific printing or testing conditions. The findings of this research comparing amplitude modulated screening with frequency modulated screening lead to the conclusion that FM screening provides greater print contrast than AM screening. This provides greater detail in the shadow areas of printed images. The findings make it difficult to draw conclusions regarding dot gain, as each of the screening technologies had statistically significant higher levels of dot gain for two of the four ink colors. Again, further study is needed to attempt greater control of variables. A computer-to-plate output workflow could be utilized to remove the inconsistencies of film-based workflows.

Keywords: graphic communication|printing|quality control|research|visual communication

How to Cite:

Dharavath, H. N., Bensen, T. M. & Gaddam, B., (2005) “Analysis of Print Attributes of Amplitude Modulated (AM) vs. Frequency Modulated (FM) Screening of Multicolor Offset Printing”, Journal of Industrial Technology 21(3).

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Published on
01 Jul 2005