Screen processing is performed for image tone reproduction. Ultra-low density areas (highlights), as well as gradation and halftone areas, require stable highlight reproduction and smoother gradation expression. Fuji Xerox has developed HQ digital screen technology for print outputs of such images in high image quality by controlling 2400-dpi based pixels.

Fig. 1 shows enlarged photos of highlighted areas of print outputs. The conventional 600-dpi based technology offers unstable image development while the 2,400-dpi based HQ digital screen technology reproduces a stable image.

Conventional technology HQ digital screen technology

Fig. 1 Enlarged photos of highlighted area print outputs

In addition, this technology offers reproduction of smooth gradations and beautiful highlight expressions by suppressing tone jump (color tone change) which is likely to occur in conventional digital/analog combined screens.

Fig. 2 Improved reproducibility of gradation and halftone

This HQ digital screen technology improves flexibility in the number of screen lines, screen shapes, and screen angles to a level approaching commercial printing by controlling ultra fine pixels of 2,400 dpi, thereby enhancing the reproduction of gradations.

Fig. 3 Shape of screen elements

This technology also generates sub-dots among dots. It optimizes the shape of screen elements in accordance with the image density of the area. In a highlighted area, “dot” that has stable density reproducibility is used as the shape of screen elements. As density increases, the shape is transformed to “line” and further to “mesh” enhancing the reproducibility of the highlighted area.

Fig. 4 Control of pixels in accordance with each density