17 April 1989 Fourier Spectra Of Digital Halftone Images Containing Random Position Errors And Reflectance Non-Uniformities
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Random laser-writer position errors in raster-scanned monochrome halftone images and the effects of non-uniformities in the recording medium are examined using Fourier analysis techniques. For a high contrast, narrow-exposure latitude recording material (typically used in halftone reproduction) with medium-sized halftone dots (25-85%), a one-dimensional halftone model is developed to derive the signal power spectrum of a halftone image containing position errors in the slow-scan (page-scan) direction. Non-uniformity in the recording medium (via sensitivity or reflectance) is modelled by representing the digital halftone image as a random amplitude-modulated signal. The spectrum of an image containing these combined effects is shown to consist of a periodic component and a random component, which is a function of position error but independent of dot size. The term signal power spectrum, in the context of this work, is the average modulus squared of the Fourier transform of an image containing these errors. The results can be generalized to include any digitally generated halftone image based on a center-growing dot configuration and containing dot size/shape distortions.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Paul W Melnychuck, "Fourier Spectra Of Digital Halftone Images Containing Random Position Errors And Reflectance Non-Uniformities", Proc. SPIE 1073, Electronic Imaging Applications in Graphic Arts, (17 April 1989); doi: 10.1117/12.952553; https://doi.org/10.1117/12.952553

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