Image quality metrics for halftone images

In this paper, different factors that affect the quality of a halftone image are examined. We investigated the quality of constant-gray-level halftones, and also of more complex halftone images with various content and degree of detail. For the constant-gray-level halftones, it was examined how their visual appearance changes with variations in their power spectrum characteristics, and for the more complex halftone images we investigated how different quantitative quality metrics can describe the quality of these images. Since the ultimate judges of image quality are human viewers, the success of the quantitative metrics as quality measures for halftones was assessed by comparing their results with the results of a psychovisual test.