Dot pattern generation technique using molecular dynamics

Abstract

We have developed a new technique for generating homogeneously distributed irregular dot patterns useful for optical devices and digital halftoning technologies. To introduce irregularity, we use elaborately designed sequences called low-discrepancy sequences instead of pseudorandom numbers. We also use a molecular-dynamics redistribution method to improve the distribution of dots. Our method can produce arbitrary density distributions in accordance with a given design. The generated patterns are free from visible roughness as well as any moiré patterns when superimposed on other regular patterns. We demonstrate that our method effectively improves luminance uniformity and eliminates moiré patterns when used for a backlight unit of a liquid-crystal display.

Nonlinear optimization to generate non-overlapping random dot patterns

“…In this section we briefly illustrate an existing simulation-based approach by Idé et al (2003). Given a domain and dot density in the domain, they consider the task to generate a dot pattern whose distribution is random and uniform.…”

“…Note that the domain corresponds to a light guide or a diffuser film. Idé et al (2003) proposed an algorithm which consists of two phases.…”

“…Generate an initial dot pattern from the given density. Idé et al (2003) utilized low discrepancy sequences so as to make a random dot distribution which is relatively uniform compared with the dot distribution by using pseudo-random numbers. 2.…”

“…. , m which satisfies the following condition: Idé et al (2003) showed that the resulting dot pattern by LDS had less visible roughness than that by pseudo-random numbers. We incorporate the dot pattern generation by LDS into our approach too.…”

“…However, it is computationally expensive and has quality problems at the edges. Idé et al (2003) proposed a two-phase algorithm to generate the dot patterns. In the first phase they generate a dot pattern by using low discrepancy sequences (LDS) (Tezuka 1993) instead of pseudo-random numbers to introduce irregularity into the dot distribution with less inter-dot overlap.…”