Douglas N. Curry

Hyperacuity laser imager

A hyperacuity laser imager utilizes gray source data and overscanned (enhanced sampling reconstruction) gray exposure to achieve fully saturated black-and-white image rendering on the photoreceptor at 4800/in. addressability in both the fast and the slow scan directions, while maintaining a 400 lines/in. frequency response. Conventional laser printing techniques render bit-mapped images at resolutions finer than required by the human visual system (for example, 600 to 1200 bit/in.) in an attempt to meet a related requirement for edge placement, precision of text, line art, and halftones. Unfortunately, this excessive bit-mapped resolution is inefficient and cumbersome to maintain in a printing system and is stiil not nearly enough to satisfy the human visual systems need for edge precision. On the other hand, a hyperacuity imager has the edge precision necessary to satisfy the human visual systems needs, and trades off excessive resolution to do so. We examine the overscanned, gray exposure characteristics of the hyperacuity laser imager and discuss how it can be viewed as a natural evolution of the current trends in laser printing technology. In addition, an order of magnitude relationship is established between addressabiity and frequency response for a hyperacuity imager, which is shown to significantly match the needs of the human visual system.

Analytic clustered halftone dots.

An analytic method of constructing high fidelity clustered halftone dots is presented.A phase addressable cell space is created which provides numerically precise 2D edge position information. Exposures are produced with variable intensity modulation to phase shift process direction dot edges, and fine granularity timing is used to adjust fast scan direction edges. This allows symmetrically thresholded halftone dots instead of sequentially thresholded dots. Advantages of this technique are more binary halftone gray levels, reduced labor content, spline based tone correction, device independence, and arbitrary screen angle and frequency. An equation which provides the desired shape and tone response over the intensity range is developed and analyzed. Shape information is extracted which is independent of the target printer characteristics. Highly accurate tone information is obtained by integrating the continuous shape function. A printer-dependent, gray enabled modulator drive function is utilized, and step wedge prints are mae with a nominal tone reproduction curve (TRC). Data from densitometer measurements are converted to spline format, and used to correct the nominal TRC with high relative accuracy. Resulting contourless tone corrected prints show very good linearity and shape definition over the entire intensity range.

Hyperacuity laser printer

A hyperacuity laser imager utilizes gray source data and overscanned gray exposure to achieve fully saturated black and white image rendering on the photoreceptor at 4800 addressability in both the fast and the slow scan directions, while maintaining 400 lines per inch frequency response. Conventional laser printing techniques render bitmapped images at resolutions finer than required by the human visual system (for example, 600 to 1200 bits per inch) in an unsuccessful attempt to meet a related requirement for edge placement precision of text, line art, and halftones. This excessive bitmapped resolution is inefficient and cumbersome to maintain in a printing system and is still not nearly enough to satisfy the human visual systems need for edge precision. On the other hand, a hyperacuity imager has the edge precision necessary to satisfy the human visual systems needs, and trades off excessive resolution to do so. This paper examines the overscanned, gray exposure characteristics of the hyperacuity laser imager and how it can be viewed as a natural evolution of the current trends in laser printing technology. In addition, it establishes an order of magnitude relationship between addressability and frequency response for a hyperacuity imager, which is shown to significantly match the needs of the human visual system.