Dithering with blue noise

Ulichney, Robert

doi:10.1109/5.3288

Cited by 380 publications

(250 citation statements)

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“…Therefore, for a given g, the pattern power spectrum has a peak in its diffraction at f g (Ulichney 1987(Ulichney , 1988. As the gray level, g, increases from 0 to 0.5, the peak diffraction moves to further angular distance ( Fig.…”

Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

“…by the minority pixels present on the device: non-metal pixels when g < 0.5 and by metal pixels conversely). The spectral energy increases as the number of minority pixels increases, peaking at g = 0.5 (Ulichney 1987(Ulichney , 1988. Most of the energy in the power spectrum of the pattern will be concentrated around the first-order diffraction, which would appear in the field of view at the spatial frequency f g (in λ/D units):…”

Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

“…This locally cancels the error of the binary optics introduced by the process of writing the required transmission (in gray-levels) into binary values. This procedure is used in gray-level reproduction with black-andwhite printing techniques (Ulichney 1987), and further details about the algorithm principle are presented in Dorrer & Zuegel (2007).…”

Section: Principle Of Microdots Apodizermentioning

confidence: 99%

“…The microdots apodizer is modeled as an aperiodic, under-filled, two-dimensional grating, which exhibits blue-noise properties because of the error-diffusion algorithm used (Ulichney 1987;Dorrer & Zuegel 2007). The binary pattern produces an averaged gray level (g = √ T , i.e.…”

Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

“…Spatially variable transmission is obtained by varying pixel density. An error-diffusion algorithm was used to calculate the density distribution that reproduces most effectively the required field transmission (Floyd & Steinberg 1976;Ulichney 1987;Dorrer & Zuegel 2007). This algorithm chooses the transmission of a given pixel of the apodizer (either 0% or 100%) by comparing the transmission required at this location to a 50% threshold, i.e.…”

Section: Principle Of Microdots Apodizermentioning

confidence: 99%

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Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Martínez

Dorrer

Carpentier³

et al. 2008

A&A

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Context. Coronagraphic techniques are required for detecting exoplanets with future Extremely Large Telescopes. One concept, the Apodized Pupil Lyot Coronagraph (APLC), combines an apodizer in the entrance aperture with a Lyot opaque mask in the focal plane. This paper presents the manufacturing and testing of a microdots apodizer optimized for the near IR. Aims. We attempt to demonstrate the feasibility and performance of binary apodizers for the APLC. This study is also relevant to coronagraph using amplitude pupil apodization. Methods. A binary apodizer was designed using a halftone-dot process, where the binary array of pixels with either 0% or 100% transmission was calculated to fit the required continuous transmission, i.e. local transmission control was obtained by varying the relative density of the opaque and transparent pixels. An error-diffusion algorithm was used to optimize the distribution of pixels that approximated the required field transmission. The prototype was tested with a coronagraphic setup in the near IR. Results. The transmission profile of the prototype agrees with the theoretical shape to within 3% and is achromatic. The observed apodized and coronagraphic images are consistent with theory. However, binary apodizers introduce high frequency noise that is a function of the pixel size. Numerical simulations were used to specify pixel size and minimize this effect, and validated by experiment. Conclusions. This paper demonstrates that binary apodizers are well suited for use in high-contrast imaging coronagraphs. The correct choice of pixel size is important and must be addressed by considering the scientific field of view.

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Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

Section: Principle Of Microdots Apodizermentioning

confidence: 99%

Section: Microdots Diffraction Stray Lightmentioning

confidence: 99%

Section: Principle Of Microdots Apodizermentioning

confidence: 99%

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Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Martínez

Dorrer

Carpentier³

et al. 2008

A&A

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Digital halftoning: A model-based perspective

Pappas¹

1996

Int. J. Imaging Syst. Technol.

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Model‐based halftoning techniques exploit the properties of the display device and the human visual system to maximize the quality of the displayed images. They rely on accurate models of the display and human perception. The focus of this article is on printers (both black and white and color) but similar techniques can be applied to other display devices. We review two model‐based techniques, the modified error diffusion algorithms and the least‐squares model‐based algorithm. Both algorithms produce images with high spatial resolution and visually pleasant textures. We also review the use of printer and eye models in blue‐noise screening techniques, which attempt to approximate the performance of error diffusion with minimal computation. We examine the performance of these halftoning techniques using both model‐based quality metrics and subjective evaluations. © 1996 John Wiley & Sons, Inc.

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