KEYWORDS: Visualization, Visual process modeling, RGB color model, Bismuth, Modulation transfer functions, Algorithm development, Optical transfer functions, Data modeling, Image quality, Monochromatic aberrations
A Visual Model (VM) is used to aid in the design of an Ultra-high Definition (UHD) upscaling algorithm that renders
High Definition legacy content on a UHD display. The costly development of such algorithms is due, in part, to the time
spent subjectively evaluating the adjustment of algorithm structural variations and parameters. The VM provides an
image map that gives feedback to the design engineer about visual differences between algorithm variations, or about
whether a costly algorithm improvement will be visible at expected viewing distances. Such visual feedback reduces the
need for subjective evaluation.
This paper presents the results of experimentally verifying the VM against subjective tests of visibility improvement
versus viewing distance for three upscaling algorithms. Observers evaluated image differences for upscaled versions of
high-resolution stills and HD (Blu-ray) images, viewing a reference and test image, and controlled a linear blending
weight to determine the image discrimination threshold. The required thresholds vs. viewing distance varied as
expected, with larger amounts of the test image required at further distances. We verify the VM by comparison of
predicted discrimination thresholds versus the subjective data. After verification, VM visible difference maps are
presented to illustrate the practical use of the VM during design.
Visually Optimal Rendering is a subpixel-based method of rendering imagery on a colour matrix display that jointly maximises displayed resolution and minimises attendant colour aliasing. This paper first outlines the Constrained Optimisation framework we have developed for the design of Optimal Rendering Filters. This framework takes into
account the subpixel geometry and colour primaries of the panel, and the luminance and chrominance Contrast Sensitivity Functions of the visual system. The resulting Optimal Rendering Filter Matrix can be designed for any regular 2D lattice of subpixels, including multi-primary lattices. The mathematical machinery of Visually Optimal Rendering is then applied to the problem of visually masking defective
subpixels on the display. The rendering filters that result are able to reduce black subpixel defects for any primary colour to the point of near invisibility at normal viewing distances. These filters have the interesting property of being shift-varying. This property allows the Optimal Filter Array to intelligently modify the values surrounding a defect in a way that takes advantage of the visual system's differing sensitivities to luminance and chrominance detail in order to best mask a defect.
In this paper we describe the MPEG2 4:2:2 Profile @ Main Level (abbreviated to 422@ML), and present a study of its characteristics. The MPEG2 422@ML provides a standard based conformance point that addresses, among other applications, the needs of the professional studio and post production environment. In the paper the requirements of such an environment for compressed digital video together with a functional description of the 4:2:2 Profile are given. The 422@ML provides a flexible compression solution that allows edit-ability, supports a wide range of bit rates, and provides good to excellent quality in both intra and inter studio environment. Our experiments show that the 422@ML is very robust in a multi generation environment, provides an efficient coding solution for transmission and storage, and provides transparency or near transparency in stressing operations such as digital video transformations, quality.
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