| Popis: |
With the technical progress in the fields of imaging and printing device, multilevel imaging and screening technologies are applied increasingly. The application of these technologies in printing field, which is as an information channel, can expand capability of information transfer. In order to obtain the characteristics of information transfer in image reproduction, in which multilevel screening technology is applied, the relationship among optical density, dot area and dot density is constructed. According to the basic definitions of information content and of information entropy, the relationship between information content/entropy and gray levels of screening dot is analyzed. Furthermore, multilevel FM screening images, which are with 4 levels, 8 levels and 16 levels and generated by a program, are analyzed and compared with bi-level screened images. The results show, that under lower imaging resolution, multilevel screening can achieve higher count of tone levels and information entropy. It is significant for the improvement of the capability of information transfer and reproduction quality of image. |
