Binary display of images when spot size exceeds step size

Area of Science:

• Digital image processing
• Computer graphics
• Information technology

Background:

• Binary digital devices often have spot sizes smaller than the spacing between addressable points (S < R).
• Existing methods struggle to accurately represent continuous-tone images on such devices.

Purpose of the Study:

• To develop a novel image representation for continuous-tone images on binary devices where spot size is less than twice the spacing (S/R < 2).
• To improve tone reproduction, minimize visible patterns, and maximize image detail.

Main Methods:

• A modified ordered dither algorithm is proposed, leveraging sub-spot size addressability.
• The approach accounts for spot overlap to ensure accurate tone reproduction.
• Implementation uses a spatially periodic mapping from continuous-tone to device input, not simple thresholding.

Main Results:

• The new representation increases the number of tonal levels per unit area.
• Enhanced visual properties of the dither matrix are achieved.
• Fourier analysis confirms the theoretical basis, and experimental results validate the findings.

Conclusions:

• The developed algorithm effectively represents continuous-tone images on binary devices with S/R < 2.
• It offers superior tone reproduction, pattern minimization, and detail rendition compared to traditional methods.